SU1199056A1 - Laser-type doppler meter of flow velocity in inter-blade passage of turbomachine - Google Patents

Abstract

A LASER DOPLERRVSKY FLOW SPEED METER IN THE INTERMEDIATE CHANNEL OF THE TURBO OF THE MUSHRINUM, containing in series the receiving-transmitting optical-electronic unit, the Doppler frequency meter and the angular position gauge, as well as the gauge of rotation, connected to the second input of the meter, the gress, and the x-plane, carrying heart, and the squeegee, carrying out the heights, and carrying out the heart, and the x-plane, carrying the heart, and carrying out the heart, and the x-ray, carrying the heart, and carrying out the heart, and the squeeze, carrying the heart, and carrying out the heart, to get the x-ray object, connected to the heart, and to get one of one of the items; aiming to improve accuracy, an amplitude discriminator, a pulse shaper, and a step coordinate meter are entered into it, with the output of the receiving and transmitting optoelectronic th unit is connected to the input of the discriminator and a first input of the pulse shaper, the output of the amplitude discriminator is connected to the second input of the pulse shaper, the output connected to the first input meter walking position, the second input of which is connected to the output of the Doppler frequency meter.

Description

The invention relates to a measurement technique and can be used to determine flow parameters on rotating elements of turbomachines, in particular in axial compressors.

The purpose of this proposal is to improve the measurement accuracy.

The invention is clear. Fig. 1, which shows the block diagram of the lauric gauge and its location in relation to the object of study, and Fig. 2, which shows the time diagram of the operation of the main elements of the device.

Laser meter (Fig. 1) contains laser -1 and sequentially connected receiving-transmitting optoelectronic unit 2, measuring Doppler frequency 3, the output of which is connected to the first input of the measuring instrument angular coordinate 4, is connected to the second input of the second sensor of the speed sensor 5, mounted on the shaft of the housing , as well as to the input of the amplitude discriminator: 6, pulse generator 7 and the step coordinate meter 8. The output of the transmitting optical-electronic unit 2 is connected to the input of the amplitude discriminator 6, the output of which is with the first input of the pulse driver 7, the second input of which is connected to the output of the receiving-transmitting opto-electronic unit 2, and the output of the peak driver 7 connecting. one

It is not the first descent of the step coordinate meter 8, the second input of which is connected to the output of the Doppler frequency meter 3.

As an object under test, an axial compressor 9 with blades 10 is depicted, at a certain radius of which there is a measuring volume 11 formed by laser beams 12. An optical window 13 is installed in the housing 14 for optical measurements above the blades.

Fig. 2a shows voltage pulses at the output of speed sensor 5. The time interval between them corresponds to one revolution of the turbomachine. .

Fig. 26 shows the voltage impulses from the output of the receiving-transmitting opto-electronic unit 2. These pulses appear at the moment when the measuring volume intersects, 11 either the surface of the blade 10 or a particle contained in the flow. . . In the first case, the 11-pulse has a bell-shaped form, and it reaches its ecTremal value at the moment when the center of the measuring volume is on the surface of the blade. The pulse duration is determined mainly by the dimensions of the measuring volume and the speed of rotation of the turbomachine, and its amplitude depends on the state of the blade surface and the angle between the blade surface and laser beams and, therefore, can vary from blade to blade. - -

In the second case, when the measuring volume is crossed by a micron particle contained in the stream and moving at almost the speed of the flow, a signal appears at the output of the receiving-transmitting opto-electronic unit whose frequency is directly proportional to the speed of the particle volume, and the amplitude is significantly less than the minimum pulse amplitude from the blade. The difference in amplitude is due to the fact that the micron particle dissipates energy equal to 10 -10 from the energy of the incident radiation, while the intensity of light scattered by a solid surface is several orders of magnitude greater.

The voltage from the output of the receiving and transmitting optical-electronic unit 2 is fed to the input of the frequency meter

99056 signal 3. Since there is no high-frequency filling in the pulses from the blades, the signal frequency meter 3i does not respond to them. When it appears on its input signal from a particle, the signal frequency meter 3 almost instantly determines its speed (information about the speed goes to a computer or to some drive), on its command output produces an IG impulse (fig.2d), which enters on the first input of the meter angular coordinates-4 (figure 1). Pulses from speed sensor 5 are fed to its second input. Using these pulses, the angular coordinate meter 4 determines the time taken for one turn of Tp-j- (FIG. 2a), as well as the time interval elapsed from the moment of the appearance of the current pulse to moment of occurrence of impulse NG (figd). The angular coordinates (inter-blade channel number) are determined by

about

5 relation C)

At the same time

oeg

The exact setting of the measuring volume in the mecha- donary canapé at the time of measuring the velocity is unknown, since the pitch t, t, t (Fig. 2d) can vary both as a result of inaccuracy in their manufacture or location and as a result. oscillations of the blades when the turbomachine. To eliminate these errors. On the 5th, the output from the transceiver output: the optoelectronic unit 2 (Fig. 1) also goes to the inputs amplitude. go discriminator b and former of u-shulses.

0 Amplitude discriminator function — separation of pulses by amplitude. A pulse appears at its output if and only if the amplitude of the input pulse exceeds

5, (modulo) threshold voltage

(figv). The threshold voltage level is chosen so that it is less than the amplitude of the pulse from the blades, but greater than the amplitude of the impulse of the particles.

0 pulse shaper7; two inputs: the first control input, .-, associated with the output of the amplitude DI-. the screener b, and the second -. signaling associated with the output of the transceiver transmitting optoelectronic unit. 2. In the case of the control at the first input-output control of the resolving pulse from the amplitude discriminator, the peak driver generates a pulse, whose leading edge coincides with the extremum of the pulse, while the output transmitter and receiver

optoelectrically blocks 2, i.e. with

the point in time when the center of the measuring point lies on the surface of the blade.

The coordinate gauge I determines the time intervals tjj-H,; T (yi .. 2g) OT; moment of the moment: with a blade measuring volume up to

the measurement of measurement; moment ne | section section measuring

volume itpB.epXHOcTbH) jto-

ipatki .. The ratio of these time intervals is the relative

.l. ... ..-. , / ..- Ti

step - coordinate t, meas

-...,.,. . .. L:.

instantaneous value of velocity V and true stepped 4 interconnect T-melera. at the time of measuring the speed can be, using the methods of statistical processing of information, for several measurements of V and t, the distribution of the speed of sweat and between 6 and 15 of the impeller from / opepxHoj:. 0 6H9Й | л6пабки to the surface of PJiToft and Lopatys.

Negotiable / Uft / jy / ñс

titJtf impulse from / particle f -,

Claims (1)

LASER DOPLERRIAN FLOW SPEED MEASURER IN THE INTER-SURFACE CHANNEL OF A TURBO MACHINE, containing serially connected transmit-receive optoelectronic unit, - a Doppler frequency meter and an angular coordinate meter, as well as a speed sensor connected to the second input of the angular coordinate meter, characterized in that., in order to improve accuracy, an amplitude discriminator, a pulse shaper and a step coordinate meter are introduced into it, while the output of the receiving-transmitting optoelectronic unit is connected to the input of the discriminator and the first input of the pulse shaper, the output of the amplitude LD scanner is connected to the second input of the pulse shaper, unity output to the first input meter walking coordinates of the second input of which is connected to move ® You are a Doppler frequency meter. t