JPS60111004A - Casing of axial flow fluid machine - Google Patents

Abstract

PURPOSE:To enable a clearance in the end of a moving blade to be adjusted, by providing a soft metallic material in the internal surface, oppositely faced to the end of the moving blade, of a casing through a shape-memory alloy of coil spring shape. CONSTITUTION:A casing 1 provides in its recessed groove 1a, opposed to the end of a moving blade 3, a soft metallic material 2 through a shape-memory alloy 5 of coil spring shape. A clearance in the end of the moving blade 3 can be adjusted in accordance with an operating condition because the shape-memory alloy 5 is extended and contracted by the temperature of fluid.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a casing for an axial flow fluid machine such as an axial flow compressor or an axial flow turbine. The gap between the rotor blade and the casing is changed at different times.

[Background of the invention]

In recent years, higher efficiency of axial flow type fluid machines has been desired from the viewpoint of energy saving and resource saving. In order to achieve high efficiency, one of the losses that cause efficiency reduction is to be minimized by the gap δ between the tip of the rotor blade 3 and the inner surface of the casing 1 as shown in FIG. There is fluid leakage loss from. Generally, this gap δ. It is known that the smaller the , the smaller the fluid leakage loss, which improves the efficiency of the axial flow type fluid machine. For this reason, in actual axial flow compressors, etc., in order to reduce the gap δQ, a soft metal material is placed on the inner surface of the casing 1.
is buried so that even if the rotor blade 3 comes into contact with the casing 1 due to rotor shaft vibration, rotor blade vibration, etc., the rotor blade 3 will not be damaged. The set gap amount δ in this method. is the only value that changes within the range of the elongation of the rotor blade 3 due to centrifugal force and the elongation of the kercing 1 due to temperature rise. Therefore, the set gap amount δ. is often determined during startup when rotor shaft vibration or rotor blade vibration is large, or in accordance with non-design truths. Therefore, during steady operation (design point) with small shaft vibrations and blade vibrations, the clearance amount δ is 7. is operated under excessive conditions,
It has the disadvantage of reducing efficiency.

The present invention was created in consideration of the above-mentioned actual situation, and the clearance amount δ between the tip of the rotor blade and the casing at startup or at a non-design point. is the maximum, and the clearance amount δ during steady operation. By changing it so that it is minimum, reliability is high,
Moreover, the object is to obtain a casing for an efficient axial flow type fluid machine.

[Summary of the invention]

The feature of the present invention is the clearance amount δ between the rotor blade tip and the casing. The advantage is that the restoring force due to the shape change of the shape memory metal is used to change the shape of the metal. It is known that alloys of Ni and 1'i and alloys of Cu, AQ, and Zn have shape memory properties. Even if these metals are deformed by applying an external force, they will only reach a certain temperature (1 to 1 full tensile strength).
When heated above the transformation temperature, it has the property of returning to its pre-deformed shape.

In the present invention, the above shape memory alloy is formed into a coil shape at a temperature higher than the transformation temperature, and a soft metal material is provided on the inner surface of the casing facing the tip of the rotor blade via the shape memory alloy coil spring. If the shape memory alloy coil spring is restored to its shape by utilizing the temperature rise of the fluid in the axial flow compressor, the gap amount δ between the tip of the rotor blade and the casing. can be changed.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be explained with reference to Figs. 2 to 6. In each figure, parts given the same reference numerals as in Fig. 1 are the same parts. , FIGS. 3 and 4 are diagrams showing the relative positional relationship of each part during startup of the axial flow compressor, and FIGS. 3 and 4 are diagrams showing the relative positional relationship of each part during steady operation. FIGS. FIG. 6 is a diagram showing the state of the mating surfaces of the soft metal materials at startup and steady state, respectively.

In each cycle, reference numeral 3 denotes a rotor blade attached to the rotor 4, and the inner surface of the casing facing the tip of the rotor blade 3 has a concave groove 1a.
is provided, and a soft metal material 2 is provided through a plurality of coil spring-like shape memory alloys 5 provided in this groove 1a. The shape memory alloy 5 is previously formed into a coiled spring shape that is expanded at a designed fluid temperature state. Therefore, the coil spring-like shape memory alloy can be expanded and contracted by an external force when the temperature is below the design fluid temperature, and is in a preformed and stretched state when the fluid temperature is the design fluid temperature.

The soft metal material 2 is divided into two parts as shown in FIG. 4, and a coil spring 6 made of ordinary metal is installed on the mating surfaces thereof. The coil spring 6 acts to repel the upper and lower halves of the soft metal material 2, which are divided into two, from each other.

Next, the operation of the above embodiment will be explained. At the time of starting the axial flow compressor, the fluid temperature is below the design fluid temperature, so
The coiled shape memory alloy 5 usually has the properties of a coiled spring made of metal. Therefore, due to the repulsive force of the coil spring 6, the coiled shape memory alloy is brought into a contracted state as shown in FIG.
Keep large initial settings without risk of contact with.

Next, when the axial flow compressor enters steady operation, the fluid temperature becomes the design value. As mentioned above, the coil spring shape memory alloy 5
When the coil spring 6 is in an extended state at the design fluid temperature, the coil spring 6, which is usually made of metal, is deformed into a contracted state due to the restoring force of the shape memory alloy, as shown in FIG. Therefore, the soft metal material 2 approaches the rotor blade 3, and the gap amount δ2 can be changed to a minimum.

According to this embodiment, the amount of gap between the tip of the rotor blade 3 and the casing 1 is kept large during startup, where the rotor shaft vibration and rotor blade vibration are relatively large, and at non-design points, and the shaft vibration is relatively small. During steady operation (design point), the gap amount can be reduced.

〔Effect of the invention〕

As explained above, the casing of the axial flow fluid machine of the present invention is configured so that a soft metal material is provided on the inner surface of the casing facing the tips of the rotor blades via a coil spring-like shape memory alloy. The advantage is that the gap between the blade tip and the casing can be made large at startup and minimized during steady operation, thereby providing a highly reliable and efficient casing for an axial flow fluid machine. East East

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of the main parts of a conventional axial flow type fluid machine without showing the casing, Figs. 2 to 6 are views showing embodiments of the present invention, and Figs. A vertical sectional view showing the main parts (Figure 2 shows the state at startup, Figure 3 shows the state during steady operation), Figure 4 is a view taken along the ■-IV line in Figure 3, Figures 5 and 6 The figure is an enlarged view of section A in FIG. 4, and is an explanatory diagram of the operation of section A. 1... Casing, 2... Soft metal material, 3... Moving blade, 5... Coil spring-like shape memory alloy. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] ] In an axial flow fluid machine consisting of a rotating rotor with rotor blades arranged in an annular flow path formed by a casing, a shape memory alloy formed in the shape of a coil spring is placed on the inner surface of the casing facing the tip of the rotor blade. A casing for an axial flow type fluid machine, characterized in that a soft metal material is provided through the casing.