RU2258902C2 - Method of measurement of radial spaces and detection of vibrations of rotor's blade of turbine machine - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: origin and intensity of oscillation process in blading of rotor wheel of turbine machine are judged from relation of average meanings of results of transformation of radial spaces along all the blades subject to control when those relations are registered during mode when there was no breakage and surging detected and oscillations of blades which correspond to these phenomena as well as during current mode, which oscillations were received at the same angular positions of locks of blades, when locks of blades found themselves in opposition to sensitive member of transformer.

EFFECT: improved reliability of measurement.

5 dwg

Description

The invention relates to the field of measuring technology and can be used to measure the radial clearances between the ends of the rotor blades and the stator of the turbomachine, as well as to detect oscillations of the blades in the blade crowns of the rotor of the turbomachine accompanying stall and surge phenomena in the compressor of the power plant.

A known method of measuring radial clearances in turbomachines is that a single-turn eddy current transducer synchronized with its rotation is brought into interaction with the ends of the blades of a working turbomachine [Raikov B.K., Sekisov Yu.N., Skobelev O.P., Khritin A. A. Eddy current gap sensors with sensitive elements in the form of a conductor segment // Instruments and Control Systems, 1996, No. 8, p.27], excited by sequences from groups of pulse packets and using its signals, radial gaps between the blades and the specified transducer are estimated for several periods rotations of a rotor of a turbomachine [and.with. USSR No. 1779908 "Method for measuring radial clearances in turbomachines", cl. G 01 B 7/08, 1990; Sekisov Yu.N., Skobelev O.P., Khritin A.A. Computer multistroboscopy in measurements of radial clearances of gas turbine engines // Avtometriya, 1996, No. 5, p.108].

The disadvantage of this method is that it does not allow to detect vibrations of the blades of the rotor of the turbomachine, for example, when stall phenomena occur in the stage and surge of the turbomachine, and also to evaluate the intensity of the oscillatory process.

The purpose of the invention is to increase the information content of measuring the radial displacements of the ends of the blades of the rotor of a turbomachine by detecting oscillations of the blades, the intensity of which can be used to assess the degree of development of stall and surge phenomena in the gas-air path of the turbomachine stage.

This goal is achieved by the fact that in the known method, namely, with the ends of the blades of the wheel of the rotor of a working turbomachine, a single-turn eddy-current transducer synchronized with its rotation is brought into interaction, excited by sequences of pulse packets, and the number of pulses in the packet is selected according to the number of controlled blades in turbomachine wheel, and the number of packets from the condition of permissible unevenness of the envelope of the output signal of the eddy current transducer, and its signals are estimated for flax clearances between the blades and said transducer within a few periods of rotation of the rotor of the turbomachine, introduces additional operations to determine the rotor blade oscillations and evaluating their intensity. The presence and intensity of vibrations of the rotor blade of the turbomachine rotor is judged by the average values of the results of the conversion of radial clearances for all controlled blades recorded in a mode in which there are obviously no stall and surge phenomena and accompanying vibrations of the blades, and in the current mode obtained with the same and the same angular positions of the blade locks when the blade locks are opposite the sensor element of the transducer. If the ratio of the average value of the measurement result of the radial clearance for all the blades of the rotor wheel obtained in the mode when there are no vibrations of the blades, to the average value of the measurement of the radial clearance for all blades obtained in the current mode will exceed the permissible level, the fact of the oscillations of the blades in the blade of the working turbomachine rotor wheels. The intensity of the oscillatory process is judged by the value of this ratio (the more intense the oscillatory process, the greater the ratio of the average).

Figure 1 presents a timing diagram explaining the process of measuring radial clearances and assessing the intensity of oscillation of the blades of the impeller of a turbomachine rotor, where τ _p is the period of rotation of the rotor, τ ₀ is the sampling step of the pulses of the interrogation of the converters, K is the number of periods of rotation of the rotor of the turbomachine, during which are interrogated eddy current transducer.

) результатов преобразования радиальных зазоров по всем лопаткам от номера пакета импульсов опроса (номера периода вращения ротора) k в выбранном сечении при отсутствии колебаний (1), при наличии колебаний отдельных лопаток (групп лопаток) (2) и при колебании всех лопаток ступени (3).Figure 2 presents a diagram explaining the receipt of averaged values (

) the results of the conversion of radial clearances for all blades from the number of the packet of interrogation pulses (number of the period of rotation of the rotor) k in the selected section in the absence of vibrations (1), in the presence of vibrations of individual blades (groups of blades) (2) and when all blades of the stage oscillate (3 )

The vibration of the ends of the blades of a rotor of a turbomachine is detected in digitally measuring radial clearances over several periods of rotor rotation in 4 stages. At the first stage (Fig. 1), the rotor rotation period τ _p is measured. At stage 2, the sampling step of the polling pulses of the converters τ _{О is} calculated. Next (step 3), the eddy current transducer is polled, according to which, during each rotation period of the rotor, pulse packets are fed to the converter, the number of pulses in the packet being equal to the number of blades (n _l ), and the pulse period:

while T»τ _about. At each revolution of the rotor, the pulse packet is shifted relative to the previous one by the sampling step τ _o calculated in stage 2.

The duration of the survey (duration of stage 3) is determined by the set of K packets of pulses and will be K periods of rotation of the rotor.

_k) по всем контролируемым лопаткам результатов преобразований, полученных при прохождении замков лопаток относительно чувствительного элемента преобразователя и соответствующих определенному номеру k^* пакета импульсов - периода вращения ротора (фиг.2)At the final stage 4, the fact of the presence of vibrations of the blades is determined and their intensity is estimated. For this, an array of averages (

_k ) for all the controlled blades of the results of the transformations obtained during the passage of the locks of the blades relative to the sensitive element of the transducer and corresponding to a certain number k ^* of the pulse train - the period of rotation of the rotor (figure 2)

- результат преобразования на i-ой лопатке на k*-ом периоде вращения ротора.Where

- the result of the conversion on the i-th blade on the k * -th period of rotation of the rotor.

_1k) к среднему значению выходного сигнала преобразователя по всем лопаткам для того же положения замка лопатки, полученного для текущего режима (

)The intensity of oscillation of the ends of the blades of the rotor of the turbomachine is carried out using the criterion q equal to the ratio of the average value of the output signal of the converter over all the blades when passing through the lock of the blade of the sensitive element of the converter obtained in the absence of oscillations (

_1k ) to the average value of the output signal of the converter for all blades for the same position of the blade lock obtained for the current mode (

)

If the criterion q exceeds a predetermined threshold value q _nop (q≥q _nop ), then a judgment is made about the presence of oscillations in the blade rim of the impeller of the turbomachine.

сохраняется, но ее максимум станет меньшим. Снижение максимума зависит от числа лопаток, охваченных колебаниями (2). Чем интенсивнее колебания, тем ближе

к горизонтальной прямой (3). Если же колебаниями охвачены все лопатки, то максимум функции

исчезнет, а график трансформируется в горизонтальную прямую (3).The graph of the change in the average values of the conversion results with a variation of k from 0 to K for all controlled blades in the absence of oscillations is shown in Fig. 2 (1) and has a pronounced maximum that corresponds to the passage of the locks of the blades of the sensitive element of the single-turn transducer and the pulse packet (rotor rotation) under the number k ^* . The appearance of oscillations violates the pattern of changes in the natural output signals of single-turn eddy-current transducers, because at the moments when the converters are polled, the ends of the blades may be outside the zone of its maximum sensitivity, and instead of the expected maximum values of the results, after the conversion of their natural output signals, lower values appear. Moreover, if not all the blades are covered by the oscillations, but only a part of them, then the nature of the changes in the function

persists, but its maximum becomes smaller. The decrease in the maximum depends on the number of blades covered by oscillations (2). The more intense the vibrations, the closer

to the horizontal line (3). If all the blades are covered by vibrations, then the maximum of the function

disappears, and the graph transforms into a horizontal line (3).

As a specific implementation of the method, we consider an example of detecting vibrations of the ends of the blades at one of the stages of the compressor of a gas turbine engine (experimental data were obtained during bench tests in real conditions). The number of controlled blades on the rotor of the test stage is 21, with only every fifth blade selected from the total number of crown blades.

₁) естественного выходного сигнала одновиткового вихретокового преобразователя для режима, когда колебания лопаток отсутствовали. Число пакетов импульсов опроса (оборотов ротора) - К=21 (номера пакетов (оборотов) k=1, 2, 3,..., 21).Table 1 and figure 3 shows the results of analog-to-digital conversion (

₁ ) the natural output signal of a single-turn eddy current transducer for the mode when the oscillations of the blades were absent. The number of packets of polling pulses (rotor revolutions) is K = 21 (packet (revolutions) numbers are k = 1, 2, 3, ..., 21).

In table 2 and figure 4 shows the results of analog-to-digital conversion (C ₂ ) of the natural output signal of the used single-turn eddy current transducer for a mode accompanied by oscillations of the blades.

₁) и при колебаниях лопаточного венца ротора (

₂).Figure 5 presents the changes in the average values of the conversion results for all controlled blades for the case under consideration in the absence of oscillations (

₁ ) and with fluctuations of the rotor blade rim (

₂ ).

As can be seen from the table. 1 and 3, in the absence of oscillations, when the positions of the locks and ends of the blades coincide, the maximum of the results of the analog-to-digital conversion corresponds approximately to the pulse packet (rotor revolution) under the number k * = 11. Then, substituting in the expressions (1, 2) the results of the analog-to-digital conversion for the regime accompanied by the oscillations of the blades (C _{2k *} ) and for the regime when there are no oscillations C _{1k *} at k * = 11 n _l = 21, we obtain

The value of the criterion q significantly exceeds 1 and corresponds to an intensive oscillatory process (figure 5). The threshold value of q _pore can be q _pore = 1.2 and its excess will indicate the presence of oscillations.

Table 1
The results of analog-to-digital conversion of the output signal of the converter for the mode when the oscillations of the blades were absent No.
k 1 2 3 4 5 6 7 8 nine 10 eleven 12 thirteen 14 fifteen 16 17 eighteen 19 twenty 21 1 97 95 85 96 106 81 102 77 87 98 64 90 105 116 92 79 64 99 105 95 77 2 97 96 96 94 118 90 107 85 86 96 67 89 116 133 94 86 73 107 107 106 83 3 104 97 115 104 136 105 122 105 90 99 81 98 123 148 114 98 78 118 108 118 95 4 133 120 155 121 166 124 153 143 101 117 100 105 143 179 155 124 107 150 126 158 124 5 169 145 206 153 215 161 199 200 133 145 144 130 188 235 200 170 145 181 147 202 167 6 220 193 261 200 270 202 245 242 172 181 192 166 234 288 243 218 188 230 182 262 217 7 285 244 328 251 364 252 303 322 223 222 244 217 288 386 301 273 248 289 223 336 272 8 366 299 412 315 480 332 428 425 283 281 300 275 394 491 422 363 321 394 280 428 369 nine 463 426 488 436 581 445 499 490 361 373 416 361 492 576 482 440 414 477 379 499 476 10 544 516 515 520 618 542 543 539 474 484 489 451 567 606 527 507 495 552 484 530 525 eleven 569 566 497 545 611 596 540 535 523 534 528 521 601 590 517 517 518 577 558 512 552 12 533 571 450 534 552 607 497 486 530 544 529 549 581 525 474 480 500 554 597 453 517 thirteen 454 521 354 467 460 558 419 402 489 508 476 523 525 435 395 417 445 486 588 361 426 14 364 439 249 380 361 469 297 286 411 426 410 453 430 332 277 292 347 393 513 261 326 fifteen 245 349 212 286 236 378 223 215 309 331 305 372 316 233 210 222 241 296 441 212 226 16 189 228 163 209 192 260 179 170 223 234 213 249 226 194 169 179 189 213 317 162 179 17 157 187 124 169 149 195 128 124 183 187 172 205 184 152 124 129 144 165 227 129 137 eighteen 108 141 90 125 116 158 95 91 134 147 128 163 145 118 86 103 98 115 180 101 99 19 75 98 73 96 87 108 66 73 96 99 89 116 103 101 63 73 69 75 123 87 77 twenty 69 73 61 74 69 83 45 61 79 81 75 86 80 83 51 64 51 54 89 74 66 21 58 77 53 63 53 61 32 45 71 65 62 69 67 70 47 60 47 47 67 70

table 2
The results of analog-to-digital conversion of the output signal of the converter for a mode accompanied by oscillations of the blades No. of shovels.
k 1 2 3 4 5 6 7 8 nine 10 eleven 12 thirteen 14 fifteen 16 17 eighteen 19 twenty 21 1 27 27 27 27 27 28 thirty 28 104 172 281 444 411 300 107 169 27 28 27 27 27 2 27 27 28 27 27 27 27 69 165 295 412 448 250 453 28 28 27 27 28 27 27 3 28 28 27 28 28 27 32 136 249 390 459 380 144 29th 27 27 28 27 27 27 27 4 27 27 28 28 28 27 27 169 353 452 449 223 28 27 27 27 27 27 27 27 27 5 29th 27 28 27 28 27 28 229 416 471 376 119 27 28 28 27 27 27 32 28 146 6 28 28 27 27 28 28 44 299 463 439 231 29th 27 28 27 28 27 28 27 143 447 7 29th 27 28 27 27 32 79 382 487 379 161 28 27 28 28 27 27 64 53 426 417 8 28 28 27 27 28 28 123 432 471 250 59 27 27 27 28 28 27 269 268 446 136 nine 28 27 27 29th 28 27 148 474 433 184 28 27 26 27 28 27 141 501 457 195 28 10 33 27 28 28 27 27 170 505 358 115 28 27 27 28 28 27 361 489 335 27 27 eleven 97 27 28 27 27 28 195 520 277 37 27 27 28 27 28 71 503 229 100 28 28 12 150 28 27 27 27 27 259 522 213 27 27 27 27 27 48 235 417 52 28 32 27 thirteen 211 32 27 28 29th 29th 290 506 170 28 27 28 27 32 182 421 202 28 thirty 29th 27 14 267 28 27 27 27 27 355 468 101 27 32 28 28 46 389 449 fifty 26 28 27 27 fifteen 356 28 28 27 27 27 385 417 49 28 28 27 28 170 466 279 28 27 27 27 55 16 429 27 28 27 28 28 417 364 28 27 27 27 27 358 380 118 27 28 27 27 331 17 465 38 28 27 27 28 441 296 27 27 27 27 44 460 204 28 29th 27 28 99 533 eighteen 492 91 28 27 28 27 461 230 28 27 28 thirty 155 450 59 27 28 27 164 346 347 19 485 131 27 28 28 28 482 189 28 28 27 28 281 301 thirty 28 26 28 412 487 91 twenty 455 169 27 27 27 28 488 157 28 27 27 27 414 161 27 28 thirty 90 445 279 28 21 411 200 28 27 27 29th 486 117 27 27 27 45 454 35 27 27 28 295 221 56 27

Claims (1)

A method for measuring radial clearances and detecting vibrations of the rotor blades of a turbomachine, which consists in the interaction of an eddy current transducer synchronized with its rotation excited by pulse packets with the ends of the rotor blades of a working turbomachine, and the radial clearances between the ends of the blades and the specified transducer are evaluated by their signals, characterized in that the appearance of vibrations and the intensity of the oscillatory process of the blades in the scapular rim of the impeller of a turbomachine judging t with respect to the average values of the results of the conversion of radial clearances for all controlled blades, registered in the mode in which there are obviously no stall and surge phenomena and accompanying vibrations of the blades, and in the current mode, obtained with the same angular positions of the blade locks, when the locks the blades are opposite the sensing element of the transducer.

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