JPH01267301A - Blade tip gap control for turbomachinery - Google Patents

Abstract

PURPOSE:To keep a stationary-time gap in the minimum as preventing any contact between an inner casing and a moving blade at the time of starting from occurring by forming a casing into an inner-outer double structure, and deforming the inner casing according to a gap between the inner casing and the moving blade. CONSTITUTION:A casing housing a rotor 1 and a moving blade 2 is divided into each of inner and outer casings 4, 3, while these casings are coupled with each other by a support spring 7. On an outer circumference of the inner casing 4, there is provided with a heater 5 deforming this casing. In addition, a gap sensor 6 is set up in space between an inner circumference of the inner casing 4 and a tip of the moving blade 2, and a gap between these elements is always measured. A current for the heater 5 is controlled via a comparator 9 and a servoamplifier 10 so as to cause the detected value of the gap sensor 6 to become the desired value 8. With this constitution, proper gap control is performed to any starting pattern.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a turbomachine consisting of a rotor, blades, and casing, and in particular, the blade tip gap fluctuates greatly due to unsteady thermal deformation and centrifugal deformation during startup. This invention relates to blade tip gap control suitable for high-temperature, high-speed turbomachinery.

[Conventional technology]

Conventional blade tip gap control for turbomachines, as described in Japanese Patent Laid-Open No. 57-35105, includes a manifold system and a control valve 13 shown in FIG. Depending on the rotational speed of the rotor blades 2, the control device 14 operates the control valve 13 to cause the cooling air to flow into the cooling manifold 12A or into the bypass flow path 12B.

[Problem to be solved by the invention]

The above conventional technology is based on gas temperature and casing temperature.

This system used experience to control the casing cooling, that is, the blade tip gap, according to the rotational speed of the rotor, but this method sequentially measures the true blade tip gap and cools the casing accordingly. rather than what controls it.

Since the control programming was done based on conventional experience, the degree of freedom was small, and there was a problem that appropriate control could not be performed for all the various activation patterns. In addition, the tip of the rotor blade or the inner periphery of the casing may cause rotating stall,
There is a possibility that these changes may change over time due to contact during abnormal operation such as surging, wear, etc., but there is a problem that these changes cannot be sufficiently reflected in control. Furthermore, the casing of general turbomachinery is thick, and there is a drawback that it is not possible to control overspeed gap fluctuations with sufficient followability by simply letting cooling air flow through the manifold.

[Means to solve the problem]

The above purpose is to constantly measure the gap at the tip of the rotor blade during startup or steady operation using a gap sensor, and either control the casing temperature to bring this gap to the target value (optimal value) or deform the casing by external force. By doing so, appropriate control can be achieved for any activation pattern. Moreover, by doubling the casing and controlling only the thin inner casing, control with sufficient followability against excessive deformation fluctuations can be achieved.

In other words, the casing is made up of an outer casing and an inner casing, and the inner casing is deformed by a heater or a piezoelectric element, in order to minimize the blade tip gap in a steady state without the blade tip touching the casing during startup. Characterized by control. In this case, it is preferable that the gap at the tip of the blade is constantly monitored by a gap sensor, and the current to the coater and the voltage to the piezoelectric element are controlled in a closed loop so that this amount is always kept at a certain target value.

[Effect]

The casing has a double structure, and the load and external forces of the entire structure are received by the outer casing, while the thinner and less rigid inner casing handles wing tip gap control, making it possible to control speeds at high speeds. Become.

In addition, by installing a gap sensor and constantly monitoring the blade tip gap, closed-loop control that can be freely added to various startup patterns and external temperature fluctuations becomes possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The casing is divided into an outer casing 3 and an inner casing 4, which are connected by a support spring 7. A heater 5 is provided on the outer periphery of the inner casing, and the gap between the inner periphery of the inner casing and the tip of the rotor blade 2, which is constantly measured by a gap sensor 6, is set to a target value of 8, which is input into the system in advance. Comparator 9. The current of the heater is controlled via the servo amplifier 10. 1 is a rotor.

FIG. 2 shows another embodiment in which the inner casing is deformed by a piezoelectric element 5'.

According to this embodiment, by providing a large number of gap sensors 6 and independently driving the piezoelectric elements in the vicinity of each gap sensor, gap control can sufficiently cope with irregular deformations of the casing such as an ellipse or an egg shape. becomes possible.

〔Effect of the invention〕

Generally, the blade tip gap of turbomachines is shown in Figure 4.

As shown in FIG. 5, the startup time decreases significantly 23 and then increases. Therefore, if a sufficient initial design gap 24 is provided to prevent the blade tip from contacting the casing 21 at these three points, the blade tip gap 25 in the steady state will become large, and the performance in the steady state will not be sufficient.

According to the present invention, this blade tip gap is constantly monitored by a sensor, and the casing is deformed so that this gap maintains the target value, so that no matter what the starting pattern, the blade tip casing will not come into contact at the time of starting. without doing,
It has sufficient effect during steady state.

[Brief explanation of the drawing]

1 and 2 are partial cross sections with circuits showing embodiments of the present invention, FIG. 3 is a partial cross section with circuits of the prior art, and FIG. 4 is a side view of the blade tip gap portion of a general turbomachine. FIG. 5 is a characteristic diagram showing the fluctuation of the gap after starting. 1... Rotor, 2... Moving blade, 3... Outer casing, 4... Inner casing, 5... Heater, 5'...
Piezoelectric element, 6... Gap sensor, 8... Target gap input, 9... Comparator, 10... Servo amplifier. No 1 Figure 1-Shilo-76--~゛7'Seyu'Boo Z-hl
7----Inner case 3-C Outer case 97 In 9-1ν, please contact [4--1 Inner case; 7'' /θ---Serho completed>7' 5--Heat 7-1st Z Figure 1-m-Rotor O-Sheet 1st position
Fu'-5----Kyoden Jujimi 3rd drawing

Claims (1)

[Claims] 1. In a turbomachine consisting of a rotor, blades, and casing, the casing is double-layered with an outer sink and an inner casing, and the inner casing is deformed into a heater or piezoelectric element, so that the blade tip contacts the casing at startup. A blade tip gap control for a turbomachine characterized by being able to control the blade tip gap in a steady state to minimize it without causing any problems.