SU236826A1 - METHOD OF MEASURING THE AMPLITUDE OF VIBRATIONS OF TUBE-MOBILE BLADES WITH IMMOBILE SENSORS - Google Patents

Description

There is a known method for measuring the amplitude of vibrations of turbo-muses blades with fixed sensors, for example, using an Elur device for measuring vibrations of blades of a turbomachine or with a stroboscope.

Measurement of the vibration amplitude of the blades is impossible in those cases when the oscillation frequency is equal to the frequency of rotation of the Maita or a multiple of it, i.e., in cases of resonant internal vibrations, because the monitored blade or flash of the stroboscope is always monitored and. it seems unshakable. Meanwhile, the measurement of the amplitude of resonant oscillations is very important, since in many cases it is these oscillations that represent the greatest danger.

The described method consists in that: they gradually change the speed of rotation of the shaft and, starting from the moment when the change in rotational speed causes the image of the object under control to move, record these movements with an ongoing change in the speed of rotation up to the moment when the image takes its original position , and then measure the distance between the extreme fixed positions, which is taken as the image of the amplitude of resonant oscillations.

This allows the vibration of blade blades to be measured, the frequency of which is the frequency of rotation of the machine shaft.

Pa figs. Figure 1 shows the scan of the machine body, the location along the unsteady disturbing force, and the distribution along the unsteady displacement of the object to be monitored, such as impeller blades, caused by the disturbing force, to a position stationary relative to the sensor body; pas figs. Figure 2 shows the amplitude-frequency characteristics at various degrees of tranquility; pas figs. 3 - phase-frequency characteristics at the same power of x; in fig. 4 shows the amplitude-phase characteristic in vector form; pas figs. Figure 5 gives an excieri. A logical comparison of the amplitudes measured in this way with those measured with the help of glued strain gauges and fluxes of the material of the turbo mash blades.

Considering a controlled object, such as a turbomachine blade, as an oscillatory system with one degree of freedom li de ffi, proportional to speed, we have a known solution of the equation of motion; : .- with AO-U - U - amn.lm goo koleoanin horse, kl1ptki (sg-1yusite, 1 na); 10 o; - kr) h) wa frequency frequency.: 1ba1P1; / - -: relatio: ({- phase shift g; ozm1tsayuyy1.sn force: and the kolsbannom caused by it Relative amylit yes it is deduced isi) 1jeniel1: - - (}, 1- -. - - | / (1 ; -) - -Y 0 h / 1- amplitude of the oscillation of the konilo (0- OTHOHieiiiie frequency to its own frequency; 30 (ii.i - self-circular frequency. Yu.Ry. RpacjiKK expressions (2) are shown in f; i-. 2 with three ras: L 1Chii ziachein x / ugarnf.michsky-35.Tkrems.ita.One abeipes otlol ei1 1 values of the phobia1eii photony to own frequency, but the main - relative and; hfiiiy-s - -, ( ) i: x,. Sdvng phase tf-arc ttj. (3) 1.; The schedule of expression (3) and shown on the FNG 3 50 for the same values of the logarithmic decree of the agent, as in Fig. 2. The abnormality is abnormal, and is significant for otionuyuyutoyottoyu to the issue, and oi ordinat - edvpg phase cf. At resonance (denominator otgovypey turns to PUL, which corresponds to the phase phase (p., -, When measuring the interchanges with a fixed sensor, the last п к рует рует рует рует отк отк 25 25 25 25 45 34 cMcincnire of the end of the blade under dyst-Instant deviations of the end of the loop for iMicAr 1l1nntud1101 about the value of the samples. smelt of the horse blade; onia lo When rezopansn1,1h fluctuations x: A --iatki; 236826 Opera tion of the USS, the location of the sensor, regulating the rubbing of the sensor, on the way through to the station. This SD | W1 phase is k times larger than the Okr / Kostn arc between the sensor's installation site and those of the Cornus, where the harmonic is excited by H, eii Enly reaches: max. ,., f „,. j shows a scan of the enclosing wheel, associated with the corns, the harmoink of the excitation of the cosmos R. cos /, corresponding to the idea of the scoop {enne scapula -U and displacement, imbued by a non-inclined sensor. Obviously, the initial phase (p ан anriooi iizvedeni and any а1 Å from д d ,, 2l. And a vectorion form (fig. 4), equation (5) expresses iroecium of a vexgor on a dim angle zigzagruyu with the angle vector vector sdr angle gr With change of speed, change speed and change, phase shift (f pz: 1 etsi but KpHisoii, but shown in Fig. 3, and the length BCKTOj a - io curve, and the case in Fig. 2. Vector nostrosy diagrams. in the pervoltage point On nr. my OX spend pr dd, ... (, Q, y ,, dd angle (p „. Perceived d.cht co. m 11e1Nmei1, enn expressed as irid) eqi11i with the axis OY, the angle is gr of the forward OU (in Fig. - Osh. d;, - ,,. From (3): (p- ----- 7 - ;: I1 - sin-f 7Г from where sin ( p - zrr: ir :: rz - :::: zr (6) 1 /, -, - .. y .V y (L) -: - I) Section (2) ia (6), we obtain the hodograph equation vector oh sin-f. .. (7) small deviations of the frequency of the test. Pleszhiv B the last expression (, we get the formula R. sin, .... (8) expressing the equation of a circle, which is easily seen by connecting the circle nentre C to points on V. N Obviously: the angle of the BOC corner, the central angle of the salt, -2 | - -f 2 f; 08 2 R s1pf, where R is the radius of the circle. So, the hodograph with the specified approximation is a circle with a radius. As shown above, it follows from (2), 4 expresses the maximum value of the resonant amplitude. So, the NPP passing of the resonance 5 10 15 20 25 full shifted blades near the sensor is equal to the project hodograph on the right opamp - resonant amplitude, moreover, out of dependence from the sensor, that is, the proposed method proves. The subject of the invention is a method for measuring the amplitude of the vibrations of the blades of a turbomagnetic stationary sensor, for example, using an Elur electronic device for measuring vibrations of a turbomachine pilot. by measuring the displacement of the signal about the occurrence of the blades of an unplugged sensor relative to the strobing of a impulse characterizing the angular and rotated machine shaft, characterized in that, in order to measure the amplitude of vibrations of the blades, whose frequency is the frequency of the shaft rotation, the tires gradually increase the speed of the shaft , fix the beginning and the end of the changed gap between the strobe) by a pseudo pulse and a signal about the passage of the blades past the fixed sensor and the magnitude of the change of the gap, they are given the amplitude of vibration current.

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