JPS58196428A - Actual external force evaluation apparatus for rotating body - Google Patents

Abstract

PURPOSE:To quantitatively evaluate external force such as fluid force working on an object to be measured by measuring response to vibration when vibrating force is applied to the object such as wing in operation with a plurality of vibrators to determine a transmission function in the actual operation. CONSTITUTION:A vibrator 1 comprises a piezoelectric element vibrator 4 and an amplifier 5. The piezoelectric element vibrator 4 is mounted to locations corresponding to the bellies or nodes to match the vibration mode of a rotor 6 and excites the rotor 6. A vibration measuring apparatus 2 comprises a vibration measuring sensor 7 such as strain gauge and piezoelectric element and an amplifier 8. An analytic computation controller 3 comprises frequency analyzer (high- speed Fourier transform device) 10 for extracting frequency components of vibration response and a calculation controller 11 having a function of controlling and computing the frequency, amplitude and phase of a vibrating force. Based on the measured vibrating force and vibration response data, a transmission function Homega at each frequency and an external force F.omega are determined whereby the evaluation of the transmission function in the necessary frequency range and external force such as fluid force F. can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to external force measurement during actual operation, and particularly to an actual external force measurement and evaluation device suitable for fluid force evaluation of an axial flow rotating machine.

The conventional rotating body adjustment method involves attaching a single piezoelectric element (also called a piezo element) to a rotating body and applying an AC voltage to the piezoelectric element from the stationary side via a slip ring or the like. Excitation of a rotating body was performed. Since the piezoelectric element is attached to a rotating field, it is required to be lightweight and small. For this reason, a single piezoelectric element could not supply a sufficient level of excitation force to accommodate a rotating body, and even for the same rotating body, only low-order vibration modes with relatively low rigidity can generate sufficient vibration response. I couldn't let it go. Furthermore, in axial flow machines, even if each member of the blade row in the same stage is vibrating in a low-order vibration mode,
The effect achieved with the fluid force differs depending on the mutual vibration phase. In particular, in self-excited vibration phenomena such as flutter, in which a blade and fluid force are coupled, the phase difference between each blade in the same blade row becomes an important influencing factor for the occurrence of the self-excited vibration phenomenon. In this way, it has been impossible to elucidate the blade vibration characteristics of axial flow machines using the conventional single piezoelectric element excitation method.

The purpose of the present invention is to apply excitation force to an object to be measured such as a blade during operation using a plurality of vibrators attached to a rotating body and measure the vibration response, thereby determining the transfer function during actual operation. An object of the present invention is to provide an actual external force evaluation device for a rotating body that can quantitatively evaluate an external force such as a fluid force acting on an object to be measured.

The present invention is characterized by: a plurality of piezo element exciters mounted on a rotating body; an amplifier having an excitation phase or excitation amplitude control function corresponding to the piezo element exciters; A vibration measuring element that measures the vibration imparted by the piezo element exciter, an amplifier that amplifies the vibration response signal from this vibration measuring element, and a frequency that extracts the vibration response frequency component corresponding to the excitation frequency component. It consists of an analysis device and a calculation control device that performs calculations according to each excitation frequency.

Hereinafter, before explaining one embodiment of the actual external force evaluation device for a rotating body of the present invention, the measurement principle thereof will be explained.

The measurement principle is an external force F such as fluid force during rotational operation, (transfer function H in the state where the target is acting) (→ and external force F, (→
This relates to the processing of measurement data for evaluating. The principle of measurement data processing will be explained below. First, a measurable binary excitation force Fl (c) is generated using a piezo element exciter.
By applying F2 (c) to the rotating body, the measurable vibration responses that occur accordingly are assumed to be 01 (→, σ2 (→). These vibration responses include vibration response components σ, ( C) is also included. Between these various data, the following relational expression is established via a transfer function H (→) that represents the vibration characteristics of the rotating body in its operating state.

σ, ((-) = H(→・F, (→
...(1) σ1(→=H(→・(F, (→+Ft(
→) ...(2)σ2(→=H(m)・(F,
(o))+Fz(→) −(3) Then, (3
)-(2) to obtain the transfer function H(→), and by substituting it into equation (2), the external force F can be obtained as shown in the following equation.

This is based on the principle that by performing the above-mentioned procedure at each excitation frequency, the external force F, (→ and transfer function H←) in the necessary frequency range can be obtained.

The actual external force evaluation device for a rotating body according to the present invention is broadly divided into three components: a vibration device 1, a vibration measurement device 2, and an analysis calculation control device 3. The excitation device 1 includes a piezo element exciter 4 that utilizes a piezoelectric effect that has the characteristics of being lightweight and compact, and a piezo element exciter 4 corresponding to each piezo element exciter 4, in order to be installed on the blades of axial flow machines and rotating machines. Each amplifier 5 can independently change the excitation amplitude or excitation phase. In addition, the plurality of piezo element vibrators 4 are installed at locations corresponding to the antinodes or nodes of the vibration mode of the rotating body 6, and the excitation phase or excitation amplitude is appropriately changed at the same excitation frequency to generate the necessary vibration. The rotating body 6 is excited so as to form a mode. This excitation method makes it possible to excite the necessary vibration mode of the rotor 6 without disturbing the flow of the rotor 6, and also makes it possible to detect the applied excitation force.

The vibration measurement device 2 includes a vibration measurement sensor 7 such as a strain gauge or a piezo element, and an amplifier 8 that amplifies a vibration response signal from the vibration measurement sensor 7.

Further, as a common feature of the vibration excitation device 1 and the vibration measurement device 2, a device for transmitting information between the rotating side and the stationary side, that is, a slip ring 9 is provided.

The basic configuration of the analysis calculation control device 3 includes a frequency analyzer (fast Fourier transformer) 10 that extracts vibration response frequency components corresponding to excitation frequency components, and a frequency analyzer (fast Fourier transformer) 10 that extracts vibration response frequency components according to excitation frequency components, and
) to a calculation control device 11 that executes the calculation of equation (5). This calculation control device 11 follows the procedure shown in FIG.
Frequency and amplitude of excitation force.

It has the function of controlling the phase and performing the above-mentioned calculations. As peripheral equipment for the analysis arithmetic and control device 11, a filter 12 is provided after the amplifier 8 of the vibration measuring device 2, and an A/D converter 13 for converting a continuous information signal into a discrete information signal.

The measurement method will be explained below according to the data processing procedure shown in FIG.

First, the piezo element vibrator 4 is attached to a corresponding location on the rotating body 6 according to the vibration mode of the rotating body 6 to be measured.

For example, if you want to measure the vibration mode of two node diameters (dotted chain lines) of a rotating body such as the centrifugal impeller shown in Fig. 3, the piezo element exciter 4 is installed at intervals of 90° in the circumferential direction. However, the excitation force may be set at the same relative excitation amplitude level, and the excitation phase angle may be alternated between 0° and 180°.

In addition, if you want to measure the primary and secondary bending vibration modes of the blade of an axial flow machine, as shown in Figure 4, a piezo element 4 is installed in consideration of the vibration mode, and in the -order mode, the primary bending displacement is measured. The mode is as shown in Figure 4(a), and the -order bending stress mode is as shown in Figure 4(b).
The in-phase excitation force is applied as shown in C), and for the secondary mode, the secondary bending displacement mode is shown in Figure 4 (d), and the secondary bending stress mode is shown in Figure 4 (e). Therefore, it is sufficient to apply an excitation force having an opposite phase as shown in FIG. 4(f).

In addition, when measuring mutually different interference effects even in the same vibration mode, a piezo element exciter 4 is installed as shown in Fig. 5, so that the excitation phase angle becomes a constant value for adjacent blades. Just apply an excitation force like this.

Next, the excitation frequency to be applied to the piezo element vibrator 4 is set. The upper and lower limits of the excitation frequency are appropriately selected according to each vibration mode, and in the vicinity of the resonance point of each vibration mode, the increments of the excitation frequency are made fine to increase the accuracy of the resonance characteristics.

Next, the task is to obtain measurement data for determining the transfer function H (→) and the external force F (→) by switching the excitation force level twice.

Next, through frequency analysis work, a vibration response component corresponding to the excitation force frequency is extracted. Based on the excitation force and vibration response data thus measured, the transfer function H (→ and external force F, (→
will be asked for. Furthermore, by changing the excitation frequency, the transfer function and external force F such as fluid force can be evaluated in a necessary frequency range.

According to the present invention, it is possible to attach a piezo element exciter to almost any rotating body and excite the necessary vibration mode in the operating state, so it is possible to obtain the transfer function in the operating state, which has been difficult to measure in the past. At the same time, it has the effect of quantitatively evaluating external forces such as fluid force.

Along with the above-mentioned external force evaluation function, it is possible to develop external force generation factors and external force prediction, and improve the accuracy of vibration response prediction during operation of rotating machines, which has the effect of improving the reliability of rotating machines. .

Furthermore, improvement of external force generation factors centered on fluid force0) will lead to improvement of fluid characteristics, which will have the effect of improving the performance of rotating machinery.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus for measuring and evaluating an actual external force of a rotating body according to the present invention, FIG. Figure 3 shows the mounting position of the piezo element exciter on the impeller, which is an embodiment of the present invention, and Figures 4 (a) to (f) show the mounting position of the piezo element exciter on the impeller, which is an embodiment of the present invention. FIG. 5 shows the mounted position and vibration mode of the piezo element vibrator according to an embodiment of the present invention. 4... Piezo element exciter, 5... Excitation force phase variable amplifier, 7... Vibration measuring element, 2... Vibration response signal amplifier, 10... Frequency analyzer, 11... Calculation Control device. (10) Sai! Written amendment (method) 1. Indication of the case Patent Application No. 78290 1982 λ Name of the invention Actual external force evaluation device for rotating body 3 Name of the person making the amendment fi; (51Q) Manufactured by Hitachi, Ltd. Representative Name 3 1) Masaru
Shigeru 4, Agent 7, Contents of amendment (1) Figure 4 of the drawings is corrected as shown in the attached drawing. (2) "What is shown in Figure 4," on page 10, line 9 to line 11 of page 10 of the specification is corrected as follows. "Figure 4 (at~(0) shows the installation position and bending vibration mode of the piezo element vibrator on the wing, which is an embodiment of the present invention, and Figure 4 (a) shows the attachment position and bending vibration mode of the wing A diagram showing the bending displacement mode, Fig. 4 (bl is a diagram showing the primary bending stress mode, Fig. 4
Figures (C1 is a diagram showing the mounting position of the piezo element vibrator for the primary mode, Figure 4 (di is a diagram showing the secondary bending displacement mode, Figure 4 (el is a diagram showing the secondary bending stress mode, Figure 4 (fl is a diagram showing the mounting position of the piezo element exciter for the secondary mode,

Claims (1)

[Claims] 1. A plurality of piezo element exciters mounted on a rotating body;
An amplifier having an excitation phase or excitation amplitude control function corresponding to these piezo element exciters, a vibration measuring element for measuring the vibration imparted by the piezo element exciter, and a vibration measuring element from the vibration measuring element. Actual external force evaluation of a rotating body consisting of an amplifier that amplifies the response signal, a frequency analyzer that extracts the vibration response frequency component according to the excitation frequency component, and a calculation control device that performs calculations according to each excitation frequency. Device. 2. The actual external force evaluation device for a rotating body according to claim 1, wherein the piezo element vibrator is mounted at a position corresponding to a node of a vibration mode of the rotating body. 3. The actual external force evaluation device for a rotating body according to claim 1, wherein the piezo element vibrator is mounted at a position corresponding to the antinode of the vibration mode of the rotating body. □4. 2. The actual external force evaluation device for a rotating body according to claim 1, wherein the excitation amplitude of each piezo element vibrator can be independently changed at the same excitation frequency. 5. The actual external force evaluation device for a rotating body according to claim 1, wherein the excitation phase of each piezo element vibrator can be changed independently at the same excitation frequency.