A method for reducing loads and vibrations on aircraft with multi-blade propellers with an even number of blades. Wind Turbine with Vertical Rotor Blade Arrangement

We have developed a design of a wind turbine with a vertical axis of rotation. Below is a detailed guide for its manufacture, carefully reading which, you can make a vertical wind generator yourself.
The wind generator turned out to be quite reliable, with low maintenance costs, inexpensive and easy to manufacture. It is not necessary to follow the list of details below, you can make some adjustments of your own, improve something, use your own, because. Not everywhere you can find exactly what is on the list. We tried to use inexpensive and high-quality parts.

Used materials and equipment:

Wind turbines with a vertical axis of rotation are not as efficient as their horizontal counterparts, however, vertical wind turbines are less demanding on their installation site.

Turbine manufacturing

1. Connecting element - designed to connect the rotor to the wind turbine blades.
2. The layout of the blades - two opposite equilateral triangles. According to this drawing, it will then be easier to arrange the corners of the blades.

If you are not sure about something, cardboard templates will help you avoid mistakes and further alterations.

The sequence of steps for manufacturing a turbine:

1. Production of the lower and upper supports (bases) of the blades. Mark and use a jigsaw to cut out a circle from ABS plastic. Then circle it and cut out the second support. You should get two absolutely identical circles.
2. In the center of one support, cut a hole with a diameter of 30 cm. This will be the top support of the blades.
3. Take the hub (hub from the car) and mark and drill four holes on the bottom support for attaching the hub.
4. Make a template for the location of the blades (fig. above) and mark on the lower support the attachment points for the corners that will connect the support and the blades.
5. Stack the blades, tie them tightly and cut to the desired length. In this design, the blades are 116 cm long. The longer the blades, the more wind energy they receive, but the downside is instability in strong winds.
6. Mark the blades for attaching the corners. Pierce and then drill holes in them.
7. Using the paddle pattern shown in the picture above, attach the paddles to the support with the brackets.

Rotor manufacturing

The sequence of actions for the manufacture of the rotor:

1. Lay the two rotor bases on top of each other, align the holes and make a small mark on the sides with a file or marker. In the future, this will help to correctly orient them relative to each other.
2. Make two paper magnet placement templates and glue them to the bases.
3. Mark the polarity of all magnets with a marker. As a "polarity tester" you can use a small magnet wrapped in a rag or electrical tape. By passing it over a large magnet, it will be clearly visible whether it is repelled or attracted.
4. Prepare epoxy resin (by adding hardener to it). And apply it evenly on the bottom of the magnet.
5. Very carefully bring the magnet to the edge of the rotor base and move it to its position. If the magnet is installed on top of the rotor, then the high power of the magnet can sharply magnetize it and it can break. And never stick your fingers or other body parts between two magnets or a magnet and iron. Neodymium magnets are very powerful!
6. Continue gluing the magnets to the rotor (don't forget to lubricate with epoxy), alternating their poles. If the magnets move under the influence of magnetic force, then use a piece of wood, placing it between them for insurance.
7. After one rotor is finished, move on to the second. Using the mark you made earlier, position the magnets exactly opposite the first rotor, but in a different polarity.
8. Put the rotors away from each other (so that they do not get magnetized, otherwise you will not pull it off later).

The manufacture of a stator is a very laborious process. Of course, you can buy a ready-made stator (try to find them with us) or a generator, but it’s not a fact that they are suitable for a particular windmill with their own individual characteristics.

The wind generator stator is an electrical component consisting of 9 coils. The stator coil is shown in the photo above. The coils are divided into 3 groups, 3 coils in each group. Each coil is wound with 24AWG (0.51mm) wire and contains 320 turns. More turns but thinner wire will give more high voltage but less current. Therefore, the parameters of the coils can be changed, depending on what voltage you require at the output of the wind generator. The following table will help you decide:
320 turns, 0.51mm (24AWG) = 100V @ 120 rpm.
160 turns, 0.0508mm (16AWG) = 48V @ 140 rpm.
60 turns, 0.0571 mm (15AWG) = 24V @ 120 rpm.

Winding coils by hand is a boring and difficult task. Therefore, in order to facilitate the winding process, I would advise you to make a simple device - a winding machine. Moreover, its design is quite simple and it can be made from improvised materials.

The turns of all coils should be wound in the same way, in the same direction, and pay attention or mark where the beginning and where the end of the coil is. To prevent unwinding of the coils, they are wrapped with electrical tape and smeared with epoxy.

The fixture is made from two pieces of plywood, a bent hairpin, a piece of PVC pipe and nails. Before bending the hairpin, heat it with a torch.

A small piece of pipe between the planks provides the desired thickness, and four nails provide the required dimensions for the coils.

You can come up with your own design of the winding machine, or maybe you already have a ready-made one.
After all the coils are wound, they must be checked for identity to each other. This can be done using scales, and you also need to measure the resistance of the coils with a multimeter.

Do not connect household consumers directly from the wind turbine! Also observe the safety precautions when handling electricity!

Coil connection process:

1. Sand the ends of the leads on each coil.
2. Connect the coils as shown in the picture above. You should get 3 groups, 3 coils in each group. With this connection scheme, a three-phase alternating current will be obtained. Solder the ends of the coils, or use clamps.
3. Choose from the following configurations:
   A. Configuration" star". In order to get a large output voltage, connect pins X,Y and Z to each other.
   B. Delta configuration. To get a high current, connect X to B, Y to C, Z to A.
   C. In order to make it possible to change the configuration in the future, grow all six conductors and bring them out.
4. On a large sheet of paper, draw a diagram of the location and connection of the coils. All coils must be evenly distributed and match the location of the rotor magnets.
5. Attach the spools with tape to the paper. Prepare epoxy resin with hardener for casting the stator.
6. Use a paint brush to apply epoxy to fiberglass. If necessary, add small pieces of fiberglass. Do not fill the center of the coils to ensure sufficient cooling during operation. Try to avoid the formation of bubbles. The purpose of this operation is to secure the coils in place and flatten the stator, which will be located between the two rotors. The stator will not be a loaded node and will not rotate.

In order to make it more clear, consider the whole process in pictures:

The finished coils are placed on waxed paper with the layout drawn. Three small circles in the corners in the photo above are the holes for mounting the stator bracket. The ring in the center prevents the epoxy from getting into the center circle.

The coils are fixed in place. Fiberglass, in small pieces, is placed around the coils. The coil leads can be brought inside or outside the stator. Be sure to leave enough lead length. Be sure to double-check all connections and ring with a multimeter.

The stator is almost ready. The holes for mounting the bracket are drilled in the stator. When drilling holes, be careful not to hit the coil leads. After completing the operation, cut off the excess fiberglass and, if necessary, clean the surface of the stator with sandpaper.

stator bracket

The pipe for attaching the hub axle was cut under right size. Holes were drilled and threaded in it. In the future, bolts will be screwed into them that will hold the axle.

The figure above shows the bracket to which the stator will be attached, located between the two rotors.

The photo above shows a stud with nuts and a sleeve. Four of these studs provide the necessary clearance between the rotors. Nuts can be used instead of a bushing bigger size, or cut washers out of aluminum yourself.

Generator. final assembly

A small clarification: a small air gap between the rotor-stator-rotor connection (which is set by a pin with a bushing) provides a higher power output, but the risk of damage to the stator or rotor increases when the axis is misaligned, which can occur when strong wind.

The left picture below shows a rotor with 4 clearance studs and two aluminum plates (which will be removed later).
The right picture shows the assembled and painted green color stator in place.

Assembly process:
1. Drill 4 holes in the top rotor plate and thread them for the stud. This is necessary to smoothly lower the rotor into place. Rest 4 studs in the aluminum plates glued earlier and install the top rotor on the studs.
The rotors will be attracted to each other with a very large force, which is why such a device is needed. Immediately align the rotors relative to each other according to the marks on the ends set earlier.
2-4. Alternately rotating the studs with a wrench, evenly lower the rotor.
5. Once the rotor has rested against the hub (providing clearance), unscrew the studs and remove the aluminum plates.
6. Install the hub (hub) and screw it on.

The generator is ready!

After installing the studs (1) and the flange (2), your generator should look something like this (see the figure above)

Stainless steel bolts serve to provide electrical contact. It is convenient to use ring lugs on wires.

Cap nuts and washers are used to fasten the connections. boards and blade supports to the generator. So, the wind generator is fully assembled and ready for tests.

To begin with, it is best to spin the windmill with your hand and measure the parameters. If all three output terminals are shorted together, then the windmill should rotate very tightly. This can be used to stop the wind turbine for service or safety reasons.

A wind turbine can be used for more than just providing electricity to your home. For example, this instance is made so that the stator generates a large voltage, which is then used for heating.
The generator considered above produces a 3-phase voltage with different frequencies (depending on the strength of the wind), and for example, in Russia a single-phase 220-230V network is used, with a fixed network frequency of 50 Hz. This does not mean that this generator is not suitable for powering household appliances. Alternating current from this generator can be converted to direct current, with a fixed voltage. And direct current can already be used to power lamps, heat water, charge batteries, and can be supplied for conversion direct current into a variable. But this is already beyond the scope of this article.

Pictured above simple circuit bridge rectifier, consisting of 6 diodes. It converts AC to DC.

Location of the wind generator

The wind generator described here is mounted on a 4-meter support on the edge of a mountain. The pipe flange, which is installed at the bottom of the generator, provides an easy and quick installation of the wind generator - it is enough to fasten 4 bolts. Although for reliability, it is better to weld.

Usually, horizontal wind turbines "like" when the wind blows from one direction, unlike vertical wind turbines, where due to the weather vane, they can turn and they do not care about the direction of the wind. Because Since this windmill is installed on the shore of a cliff, the wind there creates turbulent flows from different directions, which is not very effective for this design.

Another factor to consider when choosing a location is the strength of the wind. An archive of wind strength data for your area can be found on the Internet, although this will be very approximate, because. it all depends on the location.
Also, an anemometer (a device for measuring wind force) will help in choosing the location of the installation of the wind generator.

A little about the mechanics of the wind generator

As you know, the wind occurs due to the difference in temperature of the earth's surface. When the wind rotates the turbines of a wind generator, it creates three forces: lifting, braking and impulse. The lifting force usually occurs over a convex surface and is a consequence of the pressure difference. The wind braking force occurs behind the blades of the wind generator, it is undesirable and slows down the windmill. The impulse force comes from the curved shape of the blades. When air molecules push the blades from behind, they have nowhere to go and they gather behind them. As a result, they push the blades in the direction of the wind. The greater the lifting and impulse forces and the less braking force, the faster the blades will rotate. Accordingly, the rotor rotates, which creates a magnetic field on the stator. As a result, electrical energy is generated.

controller, mast, shank, inverter and battery.

Traditionally, the wind mechanism is endowed with three blades fixed on the rotor. When the rotor is spinning, there is a three-phase alternating current flowing to the controller, then the current is reborn into a stable voltage and goes to the battery.

Flowing through the batteries, the current feeds them and exploits them as conductors of electricity.

In the future, the current comes to the inverter, reaches the required values: alternating single-phase current 220 V, 50 Hz. With a modest expenditure of generated electricity, sufficient for the use of light and electrical appliances, the lack of current is compensated by the batteries.

How to calculate the blades?

You can calculate the diameter of a windmill for a certain power as follows:

1. The circumference of the propeller of a wind generator with a certain power, low speed and wind force, at which the required voltage is supplied, is squared by the number of blades.
2. Calculate the area of ​​this square.
3. Divide the area of ​​the resulting square by the power of the structure in watts.
4. Multiply the result with the required power in watts.
5. Under this result, you need to select the area of ​​\u200b\u200bthe square, varying the size of the square until the size of the square reaches four.
6. Inscribe the circumference of the wind generator propeller in this square.

After that, it will not be difficult to find out other indicators, for example, diameter.

The calculation of the maximum acceptable shape of the blades is quite tricky, it is difficult for a handicraft master to perform it, so you can use ready-made templates created by narrow specialists.

Blade template made of PVC pipe 160 mm in diameter:

Aluminum blade template:

You can try to independently determine the performance of the wind turbine blades.

The speed of the wind wheel is the ratio circular speed blade edge and wind speed, it can be calculated by the formula:

The power of a wind turbine is influenced by the diameter of the wheel, the shape of the blades, their location relative to the air flow, and the speed of the wind.

It can be found using the formula:

When using streamlined blades, the wind utilization factor is not higher than 0.5. With slightly streamlined blades - 0.3.

Necessary materials and tools

You will need the following materials:

• wood or plywood;
• aluminum;
• fiberglass in sheets;
• PVC pipes and accessories;
• materials available at home in the garage or utility rooms;

You need to stock up on the following tools:

• marker, you can use a pencil for drawing;
• scissors for cutting metal;
• jigsaw;
• hacksaw;
• sandpaper;

Vertical and horizontal wind generator

Can be classified by rotors:

• orthogonal;
• Darya;
• savonius;
• helicoid;
• multi-bladed with a guide vane;

The good thing is that there is no need to direct them relative to the wind, they function in any direction of the wind. Because of this, they do not need to be equipped with devices that capture the direction of the wind.

These structures can be placed on the ground, they are simple. To make such a design with your own hands is much easier than a horizontal one.

The weak point of vertical wind turbines is their low productivity, extremely low efficiency, which is why their scope is limited.

Horizontal wind turbines have a number of advantages over vertical ones. They are divided into one-, two-, three- and multi-bladed.

Single-bladed designs are the fastest, spinning twice as fast as three-bladed designs with the same wind force. The efficiency of these wind turbines is significantly higher than vertical ones.

A significant disadvantage of horizontal-axial structures is the dependence of the rotor on the direction of the wind, which is why it is necessary to install additional devices on the wind generator that capture the direction of the wind.

Choice of blade type

Blades can mainly be of two types:

• sail type;
• winged profile;

You can build flat blades like the "wings" of a windmill, that is, a sail type. It is easiest to make them from a wide variety of materials: plywood, plastic, aluminum.

This method has its downsides. When torsion of a windmill with blades made according to the principle of a sail, aerodynamic forces do not participate, torsion provides only the pressure power of the wind flow.

The performance of this device is minimal, no more than 10% of the wind force is transformed into energy. With a slight wind, the wheel will remain in a static position, and even more so will not produce energy for domestic use.

A more acceptable design would be a wind wheel with vane profile blades. In it, the outer and inner surface blades have different areas, which allows you to achieve discrepancies in air pressure on opposite surfaces of the wing. The aerodynamic force greatly increases the utilization factor of the wind turbine.

Material selection

The blades for a wind device can be made of any more or less suitable material, for example:

From PVC pipe

It is probably the easiest thing to build blades from this material. PVC pipes can be found in every hardware store. Pipes should be chosen those that are designed for sewerage with pressure or a gas pipeline. Otherwise, the air flow in strong winds can distort the blades and damage them against the generator mast.

The blades of a wind turbine are subject to severe loads from centrifugal force, and the longer the blades, the greater the load.

The edge of the blade of a two-bladed wheel of a home wind generator rotates at a speed of hundreds of meters per second, such is the speed of a bullet flying out of a pistol. This speed can lead to rupture of PVC pipes. This is especially dangerous because flying pipe fragments can kill or seriously injure people.

You can get out of the situation by shortening the blades to the maximum and increasing their number. A multi-bladed wind wheel is easier to balance and less noisy. Of no small importance is the thickness of the walls of the pipes. For example, for a wind wheel with six blades made of PVC pipe, two meters in diameter, their thickness should not be less than 4 millimeters. To calculate the design of the blades for a home craftsman, you can use ready-made tables and templates.

The template should be made from paper, attached to the pipe and circled. This should be done as many times as there are blades on the wind generator. Using a jigsaw, the pipe must be cut according to the marks - the blades are almost ready. The edges of the pipes are polished, the corners and ends are rounded so that the windmill looks nice and makes less noise.

From steel, a disk with six stripes should be made, which will play the role of a structure that combines the blades and fixes the wheel to the turbine.

The dimensions and shape of the connecting structure must correspond to the type of generator and direct current that will be involved in. Steel must be chosen so thick that it does not deform under wind blows.

aluminum

Compared to PVC pipes, aluminum pipes are more resistant to both bending and tearing. Their disadvantage lies in big weight, which requires taking measures to ensure the stability of the entire structure as a whole. In addition, you should carefully balance the wheel.

Consider the features of the execution of aluminum blades for a six-blade wind wheel.

According to the template, a plywood pattern should be made. Already according to the template from a sheet of aluminum, cut blanks of blades in the amount of six pieces. The future blade is rolled into a chute with a depth of 10 millimeters, while the scroll axis should form an angle of 10 degrees with the longitudinal axis of the workpiece. These manipulations will endow the blades with acceptable aerodynamic parameters. TO inside the blade is fastened with a threaded sleeve.

The connecting mechanism of a wind wheel with aluminum blades, unlike a wheel with blades made of PVC pipes, does not have strips on the disk, but studs, which are pieces of a steel rod with a thread suitable for the thread of the bushings.

fiberglass

Blades made from fiberglass-specific fiberglass are the most flawless, given their aerodynamic parameters, strength, weight. These blades are the most difficult to construct, because you need to be able to process wood and fiberglass.

We will consider the implementation of fiberglass blades for a wheel with a diameter of two meters.

The most scrupulous approach should be taken to the implementation of the matrix of wood. It is machined from bars along ready template and serves as a blade model. Having finished working on the matrix, you can begin to make blades, which will consist of two parts.

First, the matrix must be treated with wax, one of its sides should be coated with epoxy resin, and fiberglass should be spread on it. Apply epoxy to it again, and again a layer of fiberglass. The number of layers can be three or four.

Then you need to keep the resulting puff right on the matrix for about a day until it dries completely. So one part of the blade is ready. On the other side of the matrix, the same sequence of actions is performed.

The finished parts of the blades should be connected with epoxy. Inside, you can put a wooden cork, fix it with glue, this will fix the blades to the wheel hub. A threaded bushing should be inserted into the plug. The connecting node will become the hub in the same way as in the previous examples.

Wind wheel balancing

When the blades are completed, you need to complete the wind wheel and balance it. This should be done in a closed building. large area under the condition of complete calm, since wheel vibrations in the wind can distort the balancing results.

Wheel balancing must be done as follows:

1. Fix the wheel at such a height that it can move freely. The plane of the connecting mechanism must be perfectly parallel to the vertical suspension.
2. Achieve full static wheel and release. It shouldn't move. Then turn the wheel at an angle equal to the ratio of 360 / number of blades, stop, release, turn again, so observe for a while.
3. Tests should be carried out until the wheel is completely rotated around its axis. When the released or stopped wheel continues to swing, its part that gravitates downwards is unnecessarily heavy. It is necessary to sharpen the end of one of the blades.

In addition, you should find out how harmoniously the blades lie in the plane of rotation of the wheel. The wheel must be stopped. At a distance of about two millimeters from each edge of one of the blades, strengthen two strips that will not interfere with rotation. When spinning the wheel, the blades should not cling to the bars.

Maintenance

For long-term trouble-free operation of the wind generator, the following measures should be taken:

1. Ten or fourteen days after the start of work, the wind turbine should be inspected, especially the mounts. It is best to do this in calm weather.
2. Lubricate bearings twice a year rotary mechanism and generator.
3. If you suspect a wheel imbalance, which can be expressed in the vibration of the blades when twisting with the wind, it is necessary to perform balancing.
4. Check brushes annually pantograph.
5. As needed, cover the metal parts of the wind generator with coloring compositions.

Making blades for a wind turbine is quite within the power of a home craftsman, you just need to calculate everything, think it over, and then a real alternative to power grids will appear at home. When choosing power homemade device, it must be remembered that its maximum power should not exceed 1000 or 1500 watts. If this power is not enough, you should think about buying an industrial unit.

GOST R 52692-2006
(ISO 484-1:1981)

Group D44

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Shipbuilding

SHIP PROPELLERS

Manufacturing tolerances

Part 1

Propellers with a diameter of more than 2.5 m

Shipbuilding. Ship screw propellers. manufacturing tolerances.
Part 1. Propellers of diameter greater than 2.5 m

OKS 47.020.20
OKP 64 4700

Introduction date 2007-07-01

Foreword

Goals and principles of standardization in Russian Federation established by the Federal Law of December 27, 2002 N 184-FZ "On Technical Regulation", and the rules for the application of national standards of the Russian Federation - GOST R 1.0-2004 "Standardization in the Russian Federation. Basic provisions"

About the standard

1 PREPARED by the Research Institute for Standardization and Certification "Lot" of the Federal State Unitary Enterprise "Central Research Institute named after academician A.N. Krylov" on the basis of an authentic translation of the international standard specified in paragraph 4

2 INTRODUCED by the Technical Committee for Standardization TC 5 "Shipbuilding"

3 APPROVED AND PUT INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated December 27, 2006 N 354-st

4 This standard is a modification of the international standard ISO 484-1:1981 "Shipbuilding - Shipbuilding propellers - Manufacturing tolerances - Part 1: Propellers with a diameter of more than 2.5 m" (ISO 484-1:1981 "Shipbuilding - Ship screw propellers - Manufacturing tolerances - Part 1: Propellers of diameter greater than 2,5 m") by introducing technical deviations explained in the introduction to this standard

5 INTRODUCED FOR THE FIRST TIME


Information about changes to this standard is published in the annually published information index "National Standards", and the text of changes and amendments - in the monthly published information indexes "National Standards". In case of revision (replacement) or cancellation of this standard, a corresponding notice will be published in the monthly published information index "National Standards". Relevant information, notification and texts are also placed in information system public use - on the official website federal agency on technical regulation and metrology on the Internet


AMENDED, published in IUS N 11, 2007

Amended by database manufacturer

Introduction

Introduction

In this standard, instead of referring to the international standard ISO 3715, replaced by two standards: ISO 3715-1 "Ships and ship technology - Ship propulsion systems - Part 1: Terms and definitions of propeller geometry" and ISO 3715-2 "Ships and ship technology . Part 2. Dictionary for propulsion systems with controllable pitch propellers", which are currently not accepted in the Russian Federation, a reference is made to GOST 25815, which covers the terms and definitions of marine propellers and meets the specific needs of shipbuilding in the Russian Federation.

Reference to ISO/R 468 is not included in this International Standard because this recommendation has been replaced by ISO 468:1982 Surface roughness — Parameters, their values ​​and general rules establishing technical requirements", which was canceled without replacement in 1998.

The text of the individual structural elements changed in relation to the international standard ISO 484-1 in this standard is marked in italics.

1 Purpose

This standard specifies tolerances for the manufacture of marine propellers with a diameter of more than 2.5 m.

Note - In some cases, deviations of tolerances are possible at the request of the customer or by mutual agreement between the designer and the customer. Fixtures and measurement methods are chosen by the propeller manufacturer, provided that the tolerances are maintained with the required accuracy.

2 Scope

This standard applies to solid-cast propellers, propellers with detachable blades and controllable pitch propellers.

3 Normative references

This standard uses normative reference to the following interstate standard:

GOST 25815-83 Propellers. Terms and Definitions (ISO 3715-1:2002 "Ships and marine technology - Ship propulsion - Part 1: Propeller geometry terms and definitions", NEQ; ISO 3715-2:2001 "Ships and ship technology - Part 2: Vocabulary for propulsion systems with controllable pitch propellers", NEQ)

Note - When using this standard, it is advisable to check the effect of the reference standard in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annually published information index "National Standards", which was published as of January 1 of the current year , and according to the corresponding monthly published information signs published in the current year. If the reference standard is replaced (modified), then when using this standard, you should be guided by the replaced (modified) standard. If the referenced standard is canceled without replacement, the provision in which the reference to it is given applies to the extent that this reference is not affected.

4 Pitch measurement methods

4.1 The principle of one of the measurement methods is to draw on the arc the radius of the segment PQ, corresponding to the angle , and in the measurement of the height difference of the points R And Q relative to a plane perpendicular to the propeller axis (see Figure 1).

Picture 1

Line segment PQ shall be designed by one of the methods described in 4.1.1 or 4.1.2*.
________________
* If necessary, other methods can be applied to ensure the required accuracy.

4.1.1 Use of thickness gauges

Line segment PQ design with thickness gauges.

4.1.2 Graduated disk method

Cut length PQ is a characteristic of the angle on a part of a graduated disk of the corresponding radius (see Figure 1).

5 Section thickness measurement method

5.1 Thickness of a cylindrical section at a point S must be measured in the direction SV(see Figure 2), located in the tangential plane of the coaxial cylinder perpendicular to the step line of the discharge side of the section, and in the direction SU perpendicular to the surface of the discharge side or in the direction ST parallel to the axis of the propeller, provided that it is so defined on the drawing.

Figure 2

5.2 The maximum thickness for each radius should be determined using a pair of calipers or a profile obtained by construction, in various points: S, S, S, S etc.

5.3 To check the incoming and outgoing edges, edge templates are used. The length of the edge templates must be at least 15% of the section length, but not less than 125 mm.

Leading and trailing edges should be checked with edge gauges for Class S and Class I propellers (see Table 1). For propellers of other classes, the test is carried out at the request of the customer.


Table 1

6 Propeller classes

The accuracy class is set by the customer in accordance with table 1.

7 Pitch tolerances

Tolerances per step are given in table 2.


table 2

7.1 The pitch shall be measured at least at the radii given in Table 3.


Table 3

By agreement between the interested parties, measurements can be taken at other radii.

7.2 Measurement of local pitches for propellers of classes S and I is carried out in accordance with clause 10.

7.3 Tolerances for local pitch and section pitch given in Table 2 are increased by 50% for sections of at or less.

7.4 The propeller manufacturer may compensate for a pitch error, the tolerance for which is given in Table 2, by changing the propeller diameter only with the consent of the purchaser.

7.5 The constructive step is the baseline step.

The line of the structural step of the section is a helical base line for the considered section, for which the ordinates of the section of the discharge and suction sides are given.

It can be a line connecting the nose and tail of the section, or it can be any other correspondingly located helical line.

7.6 Local pitch at a point IN(see figure 1) is determined by measuring the height difference between points R And Q, located at equal distances from the point IN, on both sides of it ( BP=BQ), and multiplying the height difference by . The result should be compared with the local pitch measured from the discharge side profiles for the same points.

The distance between any two points when measuring the local step can be from 100 to 400 mm. One pitch measurement should be taken near the leading edge, another close to the trailing edge, and at least two more pitch measurements in between. To the extent possible, measurements should be consistent.

7.7 The section pitch and blade pitch are determined for each radius by multiplying the height difference between the measured extreme points on .

7.8 The blade pitch is determined as the arithmetic mean of the section pitches for the blade in question.

7.9 The propeller pitch is defined as the arithmetic mean of the average blade pitches.

8 Propeller Radius Tolerances

8.1 Propeller radius tolerances are given in Table 4.


Table 4

8.2 For a propeller in a nozzle, these tolerances may be reduced.

9 Blade thickness tolerances

9.1 Thickness measurements should be taken at the same radii as the pitch measurements.

9.2 The limit deviations given in Table 5 are expressed as a percentage of the local thickness.


Table 5

9.3 The maximum thicknesses indicated on the drawing, after deducting a negative tolerance, shall not be less than the thicknesses required by the classification societies.

10 Smoothness tolerances for blade sections

Blade smoothness tolerances apply only to Class S and Class I propellers at the radii at which pitches are measured.

To achieve smooth sections, deviations as a result of successive measurements of the local pitch and thickness should not differ from one another by more than half the tolerance (for example, if the tolerance is from plus 2.0% to minus 2.0%, then the allowable difference in successive deviations is 2 .0%).

To avoid excessive deviations in the overall curvature of the section, it is necessary that the algebraic sum of the deviations, expressed as a percentage, of any two consecutive measurements of the local pitch exceed the prescribed tolerance by no more than 1.5 times. For example, if the tolerance is ±2.0%, then the sum of the successive deviations should be ±3.0% (see Figure 3).

Notes

1 In the figure, the deviations are increased by 20 times.

2 Very high values ​​are underlined.

Figure 3 - Class I propeller

The smoothness of cylindrical sections is also checked using special flexible templates.

Incoming and outgoing edges should be checked with edge templates that allow you to establish the conformity of the edges with the drawing, taking into account the following tolerances of the discharge and suction sides:

±0.5 mm - for class S;

±0.75 mm - for class I.

By agreement between the manufacturer and the customer, the edges can be checked with edge gauges, consisting of three elements for each edge (see Figure 4), one element with a short nose to check the edge of the blade edge and two elements that are applied to the edge - one to the discharge, the other to the suction side. Each template covers approximately 20% of the blade length, but not more than 300 mm. These templates must be manufactured to a tolerance of 0.25 mm for class S and 0.35 mm for class I.

Figure 4

11 Blade length tolerances

11.1 The limit deviations given in Table 6 are expressed as a percentage of the ratio of the diameter to the number of blades ().


Table 6

11.2 The section lengths of each blade shall be measured at least at five radii for class S (for example: ; ; ; ; ) and at four radii for classes I, II, III.

12 Tolerances for the relative position of the blades, for the position of the center lines and for the contours of the blades

12.1 Position of the center lines of the blades

The center line is applied to the drawing as a straight line that passes through the point M on the discharge side of the blade and a point ABOUT on the axis of the propeller.

Dot M should be on cylindrical section radius greater than and, if possible, close to .

The point is chosen so that the line OM crossed the largest possible number of sections of the blade.

The relationship between the angles (corresponding to the incoming edge) and (corresponding to the outgoing edge) is indicated on the drawing (see figure 5).

indicate the size on the drawing

Figure 5

point M" on the manufactured propeller, set in such a way that a ratio equal to the ratio indicated in the drawing can be achieved on the considered radius (see figure 6).

Figure 6

Reference planes passing through a point M", used to check the contour of the leading edge and tilt of the blades as well as the angular displacement of the blade*.
_________________
* Determination of tilt - according to GOST 25815 .

12.2 Tolerances on the contour of the leading edge

Tolerances shall be calculated for the radii given in Table 3 on the respective arcs and are valid for the length of the arc (see Figure 6). Tolerances, expressed as a percentage, are given in table 6 ( - diameter, - number of blades).

Tolerances for arc length should be equal to twice the values ​​given in Table 6, provided that the contours of the blade edges are smooth.

12.3 Tolerances for angular misalignment between two adjacent blades

Permissions must be:

±1° - for screws of classes S and I;

±2° - for screws of classes II and III.

13 Tilt tolerances, position of the blade along the axis of the propeller and the relative position of the center lines of adjacent blades

The tilt is characterized by the position of the center line of the blade RR"(See Figure 7). The tilt is determined by measuring the distance to the plane W, perpendicular to the axis of rotation of the propeller, at least at points A, B And WITH located on radii or ; or ; or .

Figure 7

Table 7 shows the distance tolerances , and , expressed as a percentage of the propeller diameter , to check the position of the blades along the axis of the propeller. The same tolerances (rather than double tolerances) apply for differences: for the same blade to check the tilt and - for two adjacent blades to check the relative axial position.


Table 7

14 Surface treatment

Blade surface condition, expressed as the arithmetic mean of the deflection Ra,µm, should have a roughness not exceeding the following values:

3 (starting from the hub) - for class S propellers;

6 (starting from a radius of 0.3 ) - for class I propellers;

12 (starting from a radius of 0.4) - for class II propellers;

25 (starting from a radius of 0.5 ) - for class III propellers.

15 Static balancing

15.1 All manufactured propellers must be statically balanced.

The maximum allowable weight of the balancing weight, kg, applied at the end of the propeller blade, is determined by the formula:

Or , the smallest of them, (1)

Where - propeller weight, kg;

- outer radius of the blade, m;

- estimated number of propeller revolutions per minute, rpm;

And - coefficients depending on the propeller class are given in table 8.


Table 8

16 Measuring instruments

Maximum allowable error measuring instruments should not exceed half the tolerance on the size or parameter, and in the case of geometric measurements - 0.5 mm (choose highest value of them).



Electronic text of the document
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2007

Revision of the document, taking into account
changes and additions prepared
JSC "Kodeks"

, wind turbines, mills, hydraulic and pneumatic drives).

In blowers, vanes or vanes move the flow. In drive - the flow of liquid or gas sets the blades or blades in motion.

Operating principle

Depending on the magnitude of the pressure drop on the shaft, there may be several pressure stages.

Main types of blades

Paddle machines, as the most important element contain disks located on the shaft, equipped with profiled blades. Disks, depending on the type and purpose of the machine, can rotate at completely different speeds, ranging from units of revolutions per minute for wind turbines and mills, to tens and hundreds of thousands of revolutions per minute for gas turbine engines and turbochargers.

The blades of modern bladed machines, depending on the purpose, the task performed by this device and the environment in which they operate, have a very different design. The evolution of these designs can be traced when comparing the blades of medieval mills - water and windmills, with the blades of a wind turbine and a hydroelectric power plant.

The design of the blades is influenced by parameters such as the density and viscosity of the medium in which they operate. A liquid is much denser than a gas, more viscous and practically incompressible. Therefore, the shape and dimensions of the blades of hydraulic and pneumatic machines are very different. Due to the difference in volumes at the same pressure, the surface area of ​​the blades of pneumatic machines can be several times larger than the blades of hydraulic ones.

There are working, straightening and rotary blades. In addition, compressors can have guide vanes, as well as inlet guide vanes, and turbines can have nozzle vanes and cooled vanes.

Blade design

Each blade has its own aerodynamic profile. It usually resembles an aircraft wing. The most significant difference between a blade and a wing is that the blades operate in a flow whose parameters vary greatly along its length.

Blade profile

According to the design of the profile part, the blades are divided into blades of constant and variable sections. Blades of constant section are used for steps in which the length of the blade is not more than one tenth of the average diameter of the step. In high-power turbines, these are, as a rule, the blades of the first high-pressure stages. The height of these blades is small and amounts to 20–100 mm.

Variable section blades have a variable profile at subsequent stages, and the cross-sectional area gradually decreases from the root section to the top. In the blades of the last steps, this ratio can reach 6–8. Blades of variable section always have an initial twist, that is, angles formed by a straight line connecting the edges of the section (chord) with the turbine axis, called the angles of the sections. These angles, for reasons of aerodynamics, are set differently in height, with a smooth increase from the root to the top.

For relatively short blades, the profile swirl angles (the difference between the installation angles of the peripheral and root sections) are 10–30, and for the blades of the last stages they can reach 65–70.

The relative position of the sections along the height of the blade during the formation of the profile and the position of this profile relative to the disk is the installation of the blade on the disk and must meet the requirements of aerodynamics, strength and manufacturability.

Blades are mostly made from preformed blanks. Methods for manufacturing blades by precision casting or precision stamping are also used. Modern tendencies Increasing turbine power requires increasing the length of the blades of the last stages. The creation of such blades depends on the level of scientific achievements in the field of flow aerodynamics, static and dynamic strength and the availability of materials with the necessary properties.

Modern titanium alloys make it possible to manufacture blades up to 1500 mm long. But in this case, the limitation is the strength of the rotor, the diameter of which has to be increased, but then it is necessary to reduce the length of the blade to maintain the ratio for reasons of aerodynamics, otherwise increasing the length of the blade is ineffective. Therefore, there is a limit to the length of the blade, beyond which it cannot work effectively.

1. Scallops of the labyrinth seal of the radial clearance
2. bandage shelf
3. Combs of mechanical labyrinth seal
4. Hole for supplying cooling air to the internal channels of the cooled blade

Tail part of the blade

The designs of tail connections and, accordingly, blade shanks are very diverse and are used based on the conditions for ensuring the necessary strength, taking into account the development of technologies for their manufacture at an enterprise manufacturing turbines. Types of shanks: T-shaped, mushroom-shaped, forked, fir-tree, etc.

No one type of tail connection has a particular advantage over the other - each has its own advantages and disadvantages. Made by different factories different types tail connections, and each of them uses its own manufacturing techniques.

Connections

Turbine rotor blades are connected into packs with links of various designs: bandages riveted to the blades or made in the form of shelves (solid milled bandage); wires soldered to the blades or freely inserted into the holes in the profile part of the blades, and pressed against them by centrifugal forces; with the help of special protrusions welded to each other after the blades are assembled on the disk.

Steam turbine blades

The difference in the size and shape of the blades at different pressure stages of the same turbine

The purpose of turbine blades is to convert the potential energy of compressed steam into mechanical work. Depending on the operating conditions in the turbine, the length of its rotor blades can vary from several tens to one and a half thousand millimeters. On the rotor, the blades are arranged in steps, with a gradual increase in length, and a change in the shape of the surface. At each stage, the blades of the same length are located radially to the rotor axis. This is due to the dependence on parameters such as flow, volume and pressure.

At a uniform flow rate, the pressure at the turbine inlet is maximum, and the flow rate is minimal. When the working fluid passes through the turbine blades, mechanical work is performed, the pressure decreases, but the volume increases. Consequently, the surface area of ​​the working blade increases and, accordingly, its size. For example, the blade length of the first stage of a steam turbine with a capacity of 300 MW is 97 mm, the last - 960 mm.

Compressor blades

The purpose of compressor blades is to change the initial parameters of the gas and convert the kinetic energy of the rotating rotor into the potential energy of the compressed gas. The shape, dimensions and methods of fixing compressor blades on the rotor do not differ much from turbine blades. In the compressor, at the same flow rate, the gas is compressed, its volume decreases, and the pressure increases, therefore, at the first stage of the compressor, the length of the blades is greater than at the last.

Blades of gas turbine engines

A gas turbine engine has both compressor and turbine blades. The principle of operation of such an engine is to compress the air necessary for combustion with the help of turbocharger blades, to direct this air into the combustion chamber and, when ignited with fuel, to mechanically work the combustion products on the turbine blades located on the same shaft as the compressor. This distinguishes the gas turbine engine from any other machine, where there are either compressor blowing blades, as in superchargers and blowers of all kinds, or turbine blades, as in steam turbine power plants or in hydroelectric power plants.

Blades (vanes) of hydraulic turbines

Disc with hydraulic turbine blades

Wind turbine blades

Compared with the blades of steam and gas turbines, the blades of hydraulic turbines operate in an environment with low speeds, but high pressures. Here, the length of the blade is small relative to its width, and sometimes the width is greater than the length, depending on the density and specific volume of the liquid. Often the blades of hydraulic turbines are welded to the disk or can be manufactured entirely with it.