JPH0932501A - Moving blade of axial flow compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a change by a variation in a flow rate by lengthening a chord length of a moving blade of an axial flow compressor from a midway position running toward a tip part from a root part, and setting a projected length of a tip chord length to the compressor axis in a range of a projected length of a root chord length to the compressor axis. SOLUTION: Its chord length is changed from a midway position reaching up to the tip 5 in the vicinity of a casing 3 from a root part 4 of the root where a moving blade 1 of an axial flow compressor is installed on a hub 2. A root part blade shape 8 is installed at an angle of 40 degrees to the axial flow compressor axis C on which the moving blade 1 is installed, and a tip part blade shape 9 is installed at 60 degrees, and the tip part blade shape 9 is twisted by 20 degrees to the root part blade shape 8. A projected length L2 of the tip part blade shape 9 to the axis C is set in a range of a projected length L1 of the root part blade shape 8 to the axis C. Therefore, almost constant efficiency can be maintained over a wide flow rate range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor blade of an axial compressor used in a gas turbine or a jet engine.

[0002]

2. Description of the Related Art FIG. 6 shows a moving blade of an axial flow compressor used in a conventional gas turbine or jet engine, (A) is a development view, and (B) is a root portion (root portion) and tip of the moving blade. The angle with respect to the axis C of the compressor at the (tip) portion is shown.
As shown in (A), the chord length (chord length) of the root portion 4 of the rotor blade 1 attached to the hub 2 and the chord length of the tip portion 5 are substantially the same. Further, as shown in (B), the rotor blade 1 has a root portion airfoil 8 of θ with respect to the compressor axis C.
1, the tip part airfoil 9 is attached at an angle of θ2 (> θ1), and the projected length of the cord length with respect to the axis C is L1 at the root part and L2 at the tip part, and L2 is within the range of L1. Is installed in. A chip gap 6 is formed between the chip portion 5 and the casing 3. The moving blades in FIG. 6 represent the high-pressure compressor HPC, and the low-pressure compressor LPC such as the fan of the fan jet engine is excluded. The following explanation is also HP
Perform on C.

[0003]

With a multi-stage axial flow compressor, the flow field is correctly calculated and the airfoil is designed according to it. However, since it is difficult to calculate the flow field accurately, the actual flow and design It is extremely difficult and almost impossible to perfectly match the installed blade and its mounting angle. As a result, the efficiency greatly changes depending on the flow rate, as shown by the black circles in FIG. 5, and in particular, changes sharply before and after the peak efficiency flow rate. For this reason, it is often impossible to obtain the planned efficiency at the planned flow rate. It is desirable that the efficiency be substantially constant over a wide range of flow rates even if it is slightly lower than the peak efficiency.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an axial flow compressor rotor blade whose change is reduced due to a change in flow rate.

[0005]

In order to achieve the above object, in the invention of claim 1, the axial length of the moving blade of the axial compressor is made longer from an intermediate position from the root portion to the tip portion, and the tip cord length is increased. The projected length on the compressor axis is within the range of the projected length of the compressor axis with the root code length.

It was revealed by a three-dimensional viscous analysis that the efficiency of the moving blade drastically changes depending on the flow rate because the pressure loss due to the leakage flow in the tip clearance of the moving blade is dominant. This leakage flow is a flow from the lower surface of the blade with high pressure to the upper surface of the blade with low pressure.By reducing the pressure loss due to this leakage flow, the decrease in efficiency is reduced and the change in efficiency due to the change in flow rate is reduced. can do. It was also clarified in the above-mentioned numerical experiment that the leakage flow decreases as the chip code length increases, so the chip code length should be increased as much as possible. The upper limit of this is set so that the length of the moving blade in the axial direction of the compressor does not become long even if the length of the tip portion cord is extended. For this reason, the projection length of the tip portion cord length on the axial center may be set within the range of the projection length of the root portion cord length on the axial center of the compressor. Since the tip portion of the rotor blade is twisted with respect to the root portion as shown in FIG. 6, even if the tip portion cord length is longer than the root portion cord length, the projection range of the tip portion cord length to the axial center is set to the root portion. It can be stored within the projection range of the code length on the axis.

According to the second aspect of the present invention, the midway position has a height of 0% at the root of the moving blade and 100% at the tip, and is in the range of 50% to 80%. It is appropriate to increase from 50% when the chip portion cord length is greatly extended and from 80% when the elongation is relatively small.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are views showing the shape of an axial flow compressor blade of the embodiment, FIG. 1A is a development view, and FIG. 1B is a blade attachment angle of a root portion (root portion) and a tip portion (tip portion). . As shown in (A), the rotor blade 1 has a root portion 4 attached to the hub 2.
The cord length changes from the position on the way from the to the tip portion 5 in the vicinity of the casing 3. If the height of the rotor blade 1 is 0% at the root portion 4 and 100% at the tip portion 5, it is almost 5
The code length is the same up to 0%, and the code length increases beyond that and reaches the maximum value in the chip section 5. (B) shows an example of the mounting angle of the moving blade 1 with respect to the axis C of the axial flow compressor to which the moving blade 1 is mounted. The root portion airfoil 8 is attached to the axis C at an angle of, for example, 40 °, and the tip portion airfoil 9 is at an angle of, for example, 60 °. That is, the tip airfoil 9 is twisted by 20 ° with respect to the root airfoil 8. The projection length L2 of the tip airfoil 9 on the axis C is within the range of the projection length L1 of the root airfoil 8 on the axis C. This means that when the projection length L2 of the tip airfoil 9 on the axis C is longer than the projection range of the root airfoil 8 on the axis C, the rotor blade 1 becomes longer in the axial direction of the compressor. Therefore, it becomes necessary to extend the compressor in the axial direction. For this reason, the weight of the compressor also increases, and adverse effects also appear. Therefore, the tip cord length is increased within a range in which the moving blade 1 does not increase in the axial direction of the compressor.

Next, the performance of the rotor blade 1 in which the cord length of the tip portion 5 is larger than the cord length of the root portion 4 will be described. FIG. 2 shows the shape of the moving blade in FIG. 1 in three dimensions. FIG. 3 is a diagram showing the cord length of the rotor blade 1 shown in FIG. The cord length is almost the same from the hub 2 to about 50%, and becomes longer when it exceeds 50%.

FIG. 4 shows the pressure ratio with respect to the flow rate as a result of a numerical experiment by three-dimensional viscous analysis of the one-stage moving blade shown in FIG. The white circles indicate the blade shown in FIG. 2, and the black circles indicate the conventional blade having a substantially constant cord length. Both curves have almost the same curve, indicating that the pressure ratio is hardly affected even if the length of the tip portion cord is increased.

FIG. 5 shows the adiabatic efficiency with respect to the flow rate, which is the result of a numerical experiment by three-dimensional viscosity analysis of the one-stage rotor blade shown in FIG. The white circles indicate the blade shown in FIG. 2, and the black circles indicate the conventional blade having a substantially constant cord length. In the conventional moving blade, the adiabatic efficiency changes depending on the flow rate and has a peak value, but in the moving blade shown in FIG. 2, the adiabatic efficiency is a substantially constant value even if the flow rate changes. This constant value is smaller than the peak value of the conventional moving blade, but the adiabatic efficiency is higher than that of the conventional moving blade except in the vicinity of the peak value. It turns out to maintain efficiency.

In the blade shown in FIG. 2, since the tip portion cord length is large, the cord length is increased from a position exceeding 50% from the hub 2. However, if the tip portion cord length is not so large, the hub 2 Even if the cord length is increased from a position of about 80%, the adiabatic efficiency can be kept constant at a high value over a wide range of flow rate as shown in FIG.

[0013]

As is apparent from the above description, according to the present invention, by increasing the cord length of the moving blade of the axial compressor toward the tip portion, the flow rate of the moving blade can be increased as compared with the conventional moving blade. A substantially constant high efficiency can be maintained over a wide range.

[Brief description of drawings]

FIG. 1 shows a shape of a moving blade of an embodiment, (A) is a development view,
(B) is a figure which shows an example of the blade angle of the root part and the front-end | tip part with respect to the axial center of an axial flow compressor.

FIG. 2 shows a three-dimensional display diagram of a moving blade used for performance analysis.

FIG. 3 is a diagram showing a cord length of the rotor blade shown in FIG.

FIG. 4 is a diagram comparing the pressure ratio of the moving blade shown in FIG. 2 with that of a conventional moving blade.

FIG. 5 is a diagram comparing the heat insulating efficiency of the moving blade shown in FIG. 2 with that of a conventional moving blade.

FIG. 6 shows a shape of a conventional moving blade, (A) is a development view,
(B) is a figure which shows the blade angle of the root part and the front-end | tip part with respect to the axial center of an axial flow compressor.

[Explanation of symbols]

1 rotor blade 2 hub 3 casing 4 root portion 5 tip portion 6 tip gap 8 root portion blade type 9 tip portion blade type C compressor shaft center L1 projected length of root part cord length to compressor shaft center C L2 to compressor shaft center C Projection length of chip code

Claims (2)

[Claims] 1. A cord length of an axial flow compressor blade is made longer from a position midway from a root portion toward a tip portion, and a projection length of the tip cord length on the compressor shaft center is a root cord length of the compressor shaft center. An axial compressor blade characterized by being within the projected length range. 2. The axial compressor blade according to claim 1, wherein the midway position has a root of the blade of 0%, a tip of 100% in height, and a range of 50% to 80%.