scholarly journals Development of a PVDF Sensor Array for Measurement of the Dynamic Pressure Field of the Blade Tip in an Axial Flow Compressor

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1404
Author(s):  
Jiqing Cong ◽  
Jianping Jing ◽  
Changmin Chen
Keyword(s):  
Frequency Response ◽  
Field Measurement ◽  
Sensor Array ◽  
Pressure Field ◽  
Dynamic Pressure ◽  
Axial Flow ◽  
Actual Measurement ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

Tip clearance flow in axial flow compressor is unavoidable and responsible for pressure losses and noise generation and influences the stability of the compressor. However, necessary flow measurement in the blade tip region is a great challenge due to the small gap width as well as the structure limitation. In this paper, a polyvinylidene fluoride (PVDF) piezoelectric-film sensor array is developed to capture the dynamic pressure field over the blade tip in an axial flow compressor. The PVDF sensor array with 40 evenly distributed sensing points is fabricated directly on a 30 μm thick aluminum-metalized polarized PVDF film through photolithography. Dynamic calibration of the sensor is accomplished using acoustic source as excitation and a microphone as a reference. The test pressure range is up to 3.5 kPa and the sampling frequency is 20 kHz. The sensor presents a high signal-to-noise ratio and good consistency with the reference microphone. Sensitivity, frequency response, linearity, hysteresis, repeatability as well as the influence of temperature are also investigated through the calibration apparatus. The calibration gives credence to the relevance and reliability of this sensor for the application in dynamic pressure field measurement. The sensor is then applied to an actual measurement in a compressor. The output of the PVDF sensor array is also compared with the results of common pressure transducers, and the features of the dynamic pressure filed are discussed. The results indicate that the PVDF sensor array is capable of the dynamic pressure field measurement over the blade tip, and superior to the conventional approaches in installation, spatial resolution, frequency response, and cost. These advantages indicate its potential broad application in pressure measurement, especially for the complex spatial surface or thin-walled structure, such as the blade surface and the thin casing wall of the compressor.

Research on the Unsteady Flow in an Axial Flow Compressor Rotor Based on PVDF Piezoelectric-Film Sensor Array

2017 ◽  
Author(s):  
Jiqing Cong ◽  
Jianping Jing
Keyword(s):  
Unsteady Flow ◽  
Sensor Array ◽  
Pressure Field ◽  
Axial Flow ◽  
Acoustic Resonance ◽  
Piezoelectric Film ◽  
Film Sensor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Flow Compressor

The unsteady flow in an axial flow compressor rotor is responsible for noise generation and unexpected excitation of blade vibration; therefore, compressors may suffer from fatigue failure of blades and eventually become unable to operate. At present, a set of Kulite pressure transducers mounted on the casing wall is widely used to acquire the pressure field of unsteady flow. However, it will affect the compressor structure and it is physically impossible to mount at a small spacing to capture the variation of casing wall pressure precisely because of the size of transducers. For the requirement of measurement, a self-developed PVDF (polyvinylidene fluoride) piezoelectric-film sensor array measurement system was applied to measure and capture the pressure field distribution over the compressor rotor blade tip clearance. In this system, a multi-measuring points PVDF array, in which 40 measuring points was contained in a 70mm by 40mm rectangle area, was attached on the casing wall of the rotor blade tip. This new technique has great advantages over traditional measurement technique, such as wide frequency response, high space resolution, less impact on the compressor, easy installation and so on. Based on a multistage axial compressor rig test, the unsteady flow pattern on the casing wall was well captured by the PVDF array. And it is revealed in all measuring points that the resonance occurs all over the compressor is under one single frequency, and the pressure level of the acoustic resonance exceeds the level of the usually dominated blade passing frequency when close to the stability limit. At the same time, the acoustic resonance will be modulated with the blade passing frequency.

Numerical Simulation of Steady Air Injection Flow Control Effects on a Transonic Axial Flow Compressor

2012 ◽  
Vol 224 ◽  
pp. 352-357
Author(s):  
Islem Benhegouga ◽  
Ce Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Leading Edge ◽  
Air Injection ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

In this work, steady air injection upstream of the blade leading edge was used in a transonic axial flow compressor, NASA rotor 37. The injectors were placed at 27 % upstream of the axial chord length at blade tip, the injection mass flow rate is 3% of the chock mass flow rate, and 3 yaw angles were used, respectively -20°, -30°, and -40°. Negative yaw angles were measured relative to the compressor face in opposite direction of rotational speeds. To reveal the mechanism, steady numerical simulations were performed using FINE/TURBO software package. The results show that the stall mass flow can be decreased about 2.5 %, and an increase in the total pressure ratio up to 0.5%.

Experimental study of self-recirculating casing treatment in a subsonic axial flow compressor

2016 ◽  
Vol 230 (8) ◽  
pp. 805-818 ◽  
Author(s):  
Wei Wang ◽  
Wuli Chu ◽  
Haoguang Zhang ◽  
Yanhui Wu
Keyword(s):  
Axial Flow ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Flow Angle ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Overall Performance ◽  
Flow Compressor ◽  
Casing Treatments

Parametric studies of recirculating casing treatment were experimentally performed in a subsonic axial flow compressor. The recirculating casing treatment was parameterized with injector throat height, injection position, and circumferential coverage percentage. Eighteen recirculating casing treatments were tested to study the effects on compressor stability and on the compressor overall performance at three blade speeds. The profiles of recirculating casing treatment were optimized to minimize the losses generated by air recirculation. In the experiment, the stalling mass flow rate, total pressure ratio, and adiabatic efficiency of the compressor were measured to study the steady-state effects on the compressor performance of recirculating casing treatments, and static pressure disturbances on the casing wall were monitored to study the influence on stall dynamics. Results indicate that both the compressor stability and overall performance can be improved through recirculating casing treatment with appropriate geometrical parameters for all the test speeds. The influence on stall margin of one geometric parameter often depends on the choice of others, i.e. the interaction effects exist. In general, the recirculating casing treatment with a moderate injector throat and a large circumferential coverage is the optimal choice to enhance compressor stability. The injector of recirculating casing treatment should be placed upstream of the blade tip leading edge and the injector throat height should be lower than four times the rotor tip gap for the benefits of compressor efficiency. At 71% speed, the blade tip loading is decreased through recirculating casing treatment at the operating condition of near peak efficiency and increased near stall. Moreover, the outlet absolute flow angle is reduced in the tip region and enhanced at lower blade spans for both operating conditions. The stall inceptions are not changed with the implementation of recirculating casing treatment for all the test speeds, but the stall patterns are altered at 33% and 53% speeds, i.e. the stall with two cells is detected in the recirculating casing treatment compared with the solid casing with only one stall cell.

A Study of Stall Inceptions in a Low-Speed Axial-Flow Compressor With Various Radial Loadings

2009 ◽  
Author(s):  
J. Zhang ◽  
F. Lin ◽  
J. Chen ◽  
C. Nie
Keyword(s):  
Flow Rate ◽  
Axial Flow ◽  
High Loading ◽  
Separation Region ◽  
Flow Mechanism ◽  
Stall Inception ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor ◽  
Large Flow

In this paper, the stall inceptions in a single-stage axial flow compressor with different high loading positions generated by various radial distortions are experimentally and numerically investigated. The results indicate that the stall limit varies with the radial position of the distortion significantly. The closer the position of distortion to the blade tip, the more unstable the compressor becomes. In addition, the results demonstrate that stall inception varies with radial distortion accordingly. While with the hub distortion, the compressor exhibits modal-like disturbances prior to the stall onset, the stall is triggered by the spike-like disturbances directly with the center and tip distortions. The flow mechanism is then further explored with numerical simulations. It is shown that in the hub distortion case, the separation region caused by local high loading in large flow rate can migrate to the tip region along the span as the compressor is throttled to the stall limit. This spanwise migration plays an important role in the formation of the modal-like disturbances. Compared to the hub distortion, the modal-like disturbance in the uniform inlet flow appears in a shorter period of time because it takes less time to initiate stall cell when the separation occurs. In the tip distortion case, the separation at tip dominates so strongly that no modal-like disturbances are found before the stall onset. A discussion is given at the end of this paper to explain why in some compressors, a modal inception emerges first and the stall is triggered by the spike later.

Investigation on the influence of the structure parameters of blade tip recess on the performance of axial flow compressor

2021 ◽  
pp. 095441002199810
Author(s):  
Song Yan ◽  
WuLi Chu
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Field Analysis ◽  
Structure Parameters ◽  
Two Dimensional ◽  
Axial Flow Compressor ◽  
Aero Engine ◽  
Blade Tip ◽  
Flow Compressor

As one of the important components of an aero engine, the compressor plays an important role in improving the performance of the aero engine. The blade tip recess (BTR) has great potential and advantages in improving the performance of the compressor. It is very important to clarify the influence of the structure parameters of the BTR on the performance of the compressor. In this study, the two-dimensional results of the BTR were analyzed by using the method of variance analysis, and the two-dimensional calculation results of the BTR were used to guide the design of the BTR of axial flow compressor rotor. In the NASA Rotor 35, the influence rules of the structure parameters of BTR on the recess effect that was basically the same as the two-dimensional conditions. The optimization of the rotor BTR structure parameters may be achieved by the two-dimensional calculation. The flow field analysis showed the BTR can retard the growth rate of the blockage area of the leading edge of blade tip by weakening the tip clearance leakage flow intensity that delayed the occurrence of blade tip blockage and improved the aerodynamic stability of the rotor.

Influence of Blade Tip Surface Roughness On the Performance of a Single Stage Axial Flow Compressor

2021 ◽  
Author(s):  
Pradyumna Kodancha ◽  
Pramod Salunkhe
Keyword(s):  
Surface Roughness ◽  
Axial Flow ◽  
Single Stage ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

Abstract Numerical investigations are carried out in a single-stage subsonic axial flow compressor to unravel the influence of blade tip surface roughness on the tip leakage flow characteristics and hence the compressor performance. The studies were carried out at different tip clearance of 0.38?, 0.77?, 1.15? and 1.54? and blade tip surface roughness of 0.31? and 0.62?. The tip clearance of 0.38? with blade tip surface roughness of 0.62? resulted in the highest stall margin and pressure rise of 20.3% and 4.3%, respectively. The compressor blade loading was found to be improved by 5.9% after incorporating the blade tip surface roughness. The iso-surfaces of vorticity contour plotted using the Q-criterion showed the reduction in strength of the tip leakage vortex. The tip leakage trajectory was found to be shifted towards the suction surface of the blade for the blade tip with surface roughness. This positive alteration in the tip leakage flow structure led to the improved performance for the blade tip with surface roughness.

Unsteady Total Pressure Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor

1997 ◽  
Vol 119 (4) ◽  
pp. 985-994 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana ◽  
J. Prato ◽  
J. R. Fagan
Keyword(s):  
Total Pressure ◽  
High Speed ◽  
Pressure Field ◽  
Axial Flow ◽  
Temporal Variations ◽  
Pressure Probe ◽  
Peak Efficiency ◽  
Axial Flow Compressor ◽  
Multistage Compressors ◽  
Flow Compressor

The results from measurements of the unsteady total pressure field downstream of an embedded stage of a three stage axial flow compressor are presented in this paper. The measurements include area traverses of a high response kulite total pressure probe and a pneumatic five hole probe downstream of stator 2 at the peak efficiency operating point for the compressor. These data indicate that both the shaft-resolved and unresolved fluctuations contribute to the unsteadiness of the total pressure field in multistage compressors. Specifically, regions associated with high levels of unsteadiness and, consequently, high levels of mixing including both the hub and casing end walls and the airfoil wakes have significant levels of shaft resolved and unresolved unsteadiness. Temporal variations of stator exit flow are influenced by both shaft resolved and unresolved unsteadiness distributions. The limitations of state-of-the-art instrumentation for making measurements in moderate and high speed turbomachinery and the decomposition used to analyze these data are also discussed.

Numerical study on the effect of blade tip clearance change on stall margin of the transonic axial flow compressor rotor

2021 ◽  
pp. 095765092110368
Author(s):  
Song Yan ◽  
Wuli Chu ◽  
Yu Li ◽  
YuChen Dai
Keyword(s):  
Axial Flow ◽  
Tip Clearance ◽  
Calculation Formula ◽  
Size Change ◽  
Stall Margin ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Flow Compressor ◽  
Blade Tip Clearance

The change of the blade tip clearance size has an important impact on the performance of the compressor. Considering that the performance curve of the compressor is often limited by surge and stall boundaries, this paper used the numerical simulation method to investigate the influence mechanism of the blade tip clearance size change on the stall margin of transonic axial flow compressor rotor. By mathematically decomposing the calculation formula of the stall margin of rotor, the approximate calculation formula of the change of rotor’s stall margin was obtained. Then, the detailed quantitative analysis of the factors that affect the rotor’s stall margin was carried out, the influence weights of various factors on the rotor’s stall margin was also obtained. Finally, the physical mechanism of the change of the rotor’s performance parameters was obtained by the analysis of rotor tip flow field after the blade tip clearance size change.

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