scholarly journals Experimental and Numerical Investigation on Effects of the Steam Ingestion on the Aerodynamic Stability of an Axial Compressor

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1416
Author(s):  
Baofeng Tu ◽  
Xinyu Zhang ◽  
Jun Hu
Keyword(s):  
Boundary Layer ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Axial Flow ◽  
Stability Margin ◽  
Negative Influence ◽  
Suction Surface ◽  
Aerodynamic Stability ◽  
Stall Margin ◽  
Low Speed

In order to investigate the influence of steam ingestion on the aerodynamic stability of a two-stage low-speed axial-flow compressor, multiphase flow numerical simulation and experiment were carried out. The total pressure ratio and stall margin of the compressor was decreased under steam ingestion. When the compressor worked at 40% and 53% of the nominal speed, the stall margin decreased, respectively, by 1.5% and 6.3%. The ingested steam reduced the inlet Mach number and increased the thickness of the boundary layer on the suction surface of the blade. The low-speed region around the trailing edge of the blade was increased, and the flow separation region of the boundary layer on the suction surface of the blade was expanded; thus, the compressor was more likely to enter the stall state. The higher the rotational speed, the more significant the negative influence of steam ingestion on the compressor stall margin. The entropy and temperature of air were increased by steam. The heat transfer between steam and air was continuous in compressor passages. The entropy of the air in the later stage was higher than that in the first stage; consequently, the flow loss in the second stage was more serious. Under the combined action of steam ingestion and counter-rotating bulk swirl distortion, the compressor stability margin loss was more obvious. When the rotor speed was 40% and 53% of the nominal speed, the stall margin decreased by 6.3% and 12.64%, respectively.

scholarly journals Effect of Partial Span Aspiration on the Performance of a Transonic Axial Compressor Rotor: A Numerical Study

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Vijaykumar Jain ◽  
Quamber H. Nagpurwala ◽  
Abdul Nassar
Keyword(s):  
Boundary Layer ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Suction Side ◽  
Surface Boundary ◽  
Suction Surface ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Transonic Axial Compressor

Aspiration in an axial compressor is normally regarded as sucking out the low momentum boundary layer from blade suction surface, thus lowering the chances of flow separation and consequently that of stall under off-design operation. However, the suction mass flow does not take part in useful work and leads to loss of engine power output. This paper deals with a new concept of natural aspiration to energize blade suction surface boundary layer by injecting some fluid from pressure to suction side through a part span slot on the blade. The energized boundary layer has lesser tendency to separate, thus enhancing stall margin. Numerical simulations were carried out to study the effect of aspiration slot location and geometry on the performance and stall margin of a transonic axial compressor rotor. The computational results without aspiration slot were in fair agreement with the published experimental data. The modified rotor, with part span aspiration, showed ~3.2% improvement in stall margin at design rotational speed. The pressure ratio and efficiency of the aspirated rotor dropped by ~1.42% and ~2.0%, respectively, whereas the structural analysis did not indicate any adverse effect on the blade stress distribution in the presence of aspiration slot.

Effects of tip air injection on the aerodynamic stability of an axial flow compressor with total pressure distortion

2021 ◽  
pp. 095441002110375
Author(s):  
Baofeng Tu ◽  
Xinyu Zhang ◽  
Liang Li ◽  
Jun Hu
Keyword(s):  
Total Pressure ◽  
Critical Role ◽  
Axial Flow ◽  
Air Injection ◽  
Aerodynamic Stability ◽  
Insertion Depth ◽  
Stall Margin ◽  
Low Speed ◽  
Inlet Distortion ◽  
The Stability

The compressor is a critical component that determines the aerodynamic stability of an aero-engine. Total pressure inlet distortion decreases the thrust and shrinks the stability margin, thus inducing severe performance degradation or even flameout. Generally, tip air injection is used to reduce the adverse influence of total pressure inlet distortion on the aerodynamic stability. In the present work, an experimental investigation on the effects of tip air injection on the stability of a two-stage low-speed axial compressor with total pressure inlet distortion was carried out. A flat baffle generated the total pressure distortion at the inlet of the compressor. The stall margin of the compressor was reduced significantly by the total pressure distortion. When the dimensionless insertion depth of the flat baffle was 0.45, the stall margin decreased to 11.4%. Under the total pressure inlet distortion, tip air injection effectively improved the distortion resistance capability of the compressor. The circumferential layout of the nozzle played a critical role in the stability expansion effect of tip air injection under the inlet flow condition of the total pressure distortion. The modal wave disturbance was likely to occur in the distortion-affected region (the low-pressure region and the mixing region). Tip air injection did not inhibit the generation of the modal wave but restrained the development of the modal wave into the stall cell. It improved the low-speed compressor’s tolerance to the modal wave and allowed a higher amplitude modal wave to occur.

Numerical Investigation on the Effect of Bleed Port With Self-Recirculating Casing Treatment on the Stability of a 1.5-Stage Transonic Compressor

2019 ◽  
Author(s):  
Yiming Zhong ◽  
WuLi Chu ◽  
HaoGuang Zhang
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Stability Margin ◽  
Axial Position ◽  
Stable Operation ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Efficiency

Abstract Compared to the traditional casing treatment, the self-recirculating casing treatment (SCT) can improve or not decrease the compressor efficiency while achieving the stall margin improvement. For the bleed port, the main design indicator is to reduce the flow loss caused by suction, while providing sufficient jet flow and jet pressure to the injector. In order to gain a better study of the bleed port stabilization mechanisms, the bleed configuration was parameterized with the bleed port inlet width and the bleed port axial position. Five kinds of recirculating casing treatments were applied to a 1.5-stage transonic axial compressor with the method of three-dimensional unsteady numerical simulation. Fifteen identical self-recirculating devices are uniformly mounted around the annulus. The numerical results show that the SCT can improve compressor total pressure ratio and stability, shift the stall margin towards lower mass flows. Furthermore, it has no impact on compressor efficiency. The optimal case presents that stability margin is improved by 6.7% employing 3.1% of the annulus mass flow. Expanding bleed port inlet width to an intermediate level can further enhance compressor stability, but excessive bleed port inlet width will reduce the stabilization effect. The optimal bleed port position is located in the blocked area of the low energy group at the top of the rotor. In the case of solid casing, stall inception was the tip blockage, which was mainly triggered by the interaction of the tip leakage vortex and passage shock. From radial distribution, the casing treatment predominantly affects the above 70% span. The reduction of tip reflux region by suction effect is the main reason for the extension of stable operation range. The SCT also has an obvious stability improvement in tip blockage stall, while delaying the occurrence of compressor stall.

Effect of J-Shaped Casing Treatment on Flow Stability and Performance of an Axial Compressor

2012 ◽  
Author(s):  
Ramjan R. Pathan ◽  
Quamber H. Nagpurwala ◽  
Ananthesha Bhat
Keyword(s):  
Incidence Angle ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Stability Margin ◽  
Tangential Component ◽  
Favourable Effect ◽  
Slight Reduction ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor

Casing Treatment (CT) is one of the passive methods to increase the stability margin of the compress and hence that of the aircraft jet engines. In this paper, a novel J-shaped axial CT slot geometry is designed and numerically analysed for its effect on the performance of a single stage NACA transonic compressor. The predicted performance of the isolated rotor was validated by comparing with the published experimental results. The predicted efficiency of the baseline transonic rotor agreed well with experimental data, but the total pressure ratio was under predicted over the entire operating range. The J-shaped CT slots, with 100% axial coverage over the rotor tip chord, were able to extend the stall mass flow rate by almost 19.45% compared to the baseline rotor, accompanied with a slight reduction in rotor efficiency by 1.42%. The high pressure air entered the slots at rotor exit and flowed back through the slots and the plenum, and ejected at the rotor inlet to energise the low momentum end wall flow. The interaction of main inlet flow and the ejected flow having large tangential component of velocity, had favourable effect on the rotor incidence angle, and hence on rotor stall margin.

The Experiment Research on the Performance of Low Speed Axial-Compressor by External Acoustic Excitation

2004 ◽  
Author(s):  
Zhi-Ping Li ◽  
Zhi-Qiang Gong ◽  
Yan Liu ◽  
Ya-Jun Lu
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Pressure Ratio ◽  
Excitation Frequency ◽  
Axial Compressor ◽  
Excitation Amplitude ◽  
Separated Flows ◽  
Stall Margin ◽  
Low Speed ◽  
Acoustic Excitations

This paper investigates the control of large-scale separated flows inside a low-speed axial-compressor by using external acoustic excitations. Experiment studies on the characteristics of flow field and the performance of compressors under external unsteady acoustic excitations are carried out in a low speed axial-compressor. The results indicate that the excitation frequency and excitation amplitude are of key importance for controlling large-scale separated flows. When the unsteady excitation is of the most effective frequency with proper amplitude, the large-scale separated flow is controlled effectively and the flow field becomes more regular near the compressor’s stall margin. At the same time, the performances of the compressor are enhanced: the efficiency is increased by about 1∼2%, the pressure ratio is increased by 2∼3% and the stall margin of the compressor is broadened remarkably too.

Aerodynamic Research on Highload Axial Compressor With a Chordwise Split

1989 ◽  
Author(s):  
Zhi-Gang Zhang ◽  
Ping-Cheng Shen ◽  
Hong Zhu ◽  
Jia-Hua Lu ◽  
Yan-Sheng Li
Keyword(s):  
Boundary Layer ◽  
Pressure Ratio ◽  
Research Work ◽  
Axial Compressor ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Turning Angle ◽  
Pressure Surface ◽  
Work Done ◽  
The Mathematical Model

This paper deals with a novel configuration of axial compressor cascade with chordwise split. Contrast to tandem cascade and cascade with a slot from pressure surface to suction surface, the cascade with a chordwise split not only controls the separation of boundary layer, increases flow turning angle and stage load, thus the compressor length can be shortened or pressure ratio increased, but also the flow pattern in the split is different. The research work done shows that the cascade with chordwise split avoids or delays the separation of boundary layer on blade surface effectively thus may lead to a larger camber angle. The theoretical model and program for locating the split position and predicting flow field in cascade passage by using Finite Element Method are given. Experiments have verified the mathematical model and the preferable effects of the chordwise split. The results of calculation correspond to the test data satisfactorily.

Stall Margin Improvement of a Single Stage Transonic Axial Flow Compressor Using Naturally Aspirated Slots

2015 ◽  
Author(s):  
Hari Krishna Borra ◽  
Dilipkumar Bhanudasji Alone
Keyword(s):  
Boundary Layer ◽  
Steady State ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Flow ◽  
Compressor Stage ◽  
Suction Surface ◽  
Stall Margin ◽  
Blade Tip ◽  
Flow Compressor

This paper describes the method to improve the stall margin of transonic axial flow compressor by controlling the boundary layer on the suction surface of the rotor blade tip through natural aspiration. Aspiration slots in the compressor blade are intended to energize the flow by increasing its momentum on the suction surface. This phenomenon of boundary layer control can delay the flow separation and hence results in enhancement of the stall margin of the compressor stage. Flow behavior with aspiration slots and its performance are evaluated using commercially available numerical software. Steady state RANS simulations with three dimensional implicit pressure-based coupled solver and turbulence model SST k-ω are used. The effect of natural aspiration slot on the rotor blade performance is computed numerically. The main objective of the study was to identify the optimum location of the aspiration slot along the chord of the compressor on the rotor blade. The axial location chosen for the performance evaluations were 20%,40%,50%,60% and 70% of the rotor blade axial tip chord. By comparing the numerical simulation results with the steady state behavior in the absence of the aspirated slots, the optimized location of the aspiration slot that results in maximum stall improvement is identified. At the optimized location, natural aspiration slots on the rotor blade tip improved the stall margin with the minimum reduction in efficiency and stage pressure ratio when compared to base model. After critically understanding the performance with straight aspiration slots the compressor stage performance has enhanced further by orienting the aspiration slots. The numerical three dimensional results conclude an optimal improvement in the stall margin for the slots near the trailing edge of the rotor. The prediction shows that with the inclined aspiration slots at proper location it is possible to improve the stall margin of the compressor stage and also to restore the stage efficiency.

Mechanism Analysis of the Influence of Blade Thickness Deviation on The Performance of Axial Flow Compressor

2021 ◽  
Author(s):  
Tianyuan Ji ◽  
Wuli Chu ◽  
Zhengtao Guo ◽  
Jibo Yang
Keyword(s):  
Shock Wave ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Stability Margin ◽  
Simulation Method ◽  
Mechanism Analysis ◽  
Low Speed ◽  
Blade Thickness ◽  
Thickness Deviation

Abstract The deviation between the actual processed blade and the designed blade shape inevitably occurs in the process of compressor blade manufacturing. Rotor37 was used as the research object and a three-dimensional steady Reynolds averaged Navier-Stokes simulation method was adopted in order to study the influence mechanism of blade thickness deviation on blade performance. The blade was parameterized and the blade thicknesses were increased or decreased uniformly, with changes of 0.06mm and 0.1mm respectively. Results illustrate that the blade thickness deviation affects the total pressure ratio, isentropic efficiency and stability margin of the single-stage rotor. Increasing the blade thickness will inhibit the transport of low speed airflow from blade root area to blade tip area along the radial direction. In the peak efficiency condition, this inhibit will cause low speed airflow to converge in the middle of the blade and increase the flow separation loss; while in the reference near stall condition, the inhibition of low speed airflow transport will weaken the accumulation of low energy airflow in the tip area, reduce the loss in the corner area, and expand the stable working range of the blade. Further, increasing the blade thickness causes the shock wave position to move backward and the shock wave intensity will decrease.

A CFD-Based Investigation of Boundary Layer Skew in the Hub Region of a Low Speed Axial Compressor and its Influence on Performance and Losses

2009 ◽  
Author(s):  
M. Hilgert ◽  
M. Bo¨hle
Keyword(s):  
Boundary Layer ◽  
Axial Compressor ◽  
Surface Flow ◽  
Flow Coefficient ◽  
Wall Region ◽  
Suction Surface ◽  
Local Flow ◽  
Low Speed ◽  
Wall Area ◽  
End Wall

The flow in the hub end-wall region has a substantial influence on the aerodynamic performance of axial-flow compressors. A numerical investigation of this three-dimensional flow phenomenon, often referred to as boundary layer skew, that contributes to the interaction between the end-wall and blade suction surface flow, thus determining the losses in this area, is the topic of this report. A single-staged model compressor (flow coefficient: 0.5, work coefficient: 0.34) with a 7-blade rotor row and a highly loaded 11-blade stator row was designed for the simulation. To account for the complex time-dependent flow patterns in the end-wall area, a transient calculation with the rotor and stator rows fully modeled (360°) is carried out. The flow is assumed to be incompressible as the velocities of the low-speed axial compressor do not exceed a Mach-number value of 0.3. The calculations show that the boundary layer in the end-wall region is highly skewed and transient. There is a direct connection to local flow phenomena such as separation as well as to global pressure loss coefficient distributions in pitchwise and streamwise direction. Different levels of flow overturning in the end-wall area are observed, depending on the boundary layer skewness varying by simulating the compressor at different operational points.

The effect of high temperature steam ingestion on aerodynamic performance and stability of a low-speed axial compressor

2019 ◽  
Vol 234 (3) ◽  
pp. 871-886
Author(s):  
Baofeng Tu ◽  
Luyao Zhang ◽  
Wenjun Fu ◽  
Jun Hu
Keyword(s):  
High Temperature ◽  
Mass Fraction ◽  
Axial Compressor ◽  
Stability Margin ◽  
Aerodynamic Stability ◽  
Two Stage ◽  
Low Speed ◽  
High Temperature Steam ◽  
The Stability ◽  
The Impact

To investigate the effect of high temperature steam ingestion on the aerodynamic stability of a multistage axial compressor, a two-stage low-speed axial compressor was studied, and full-annulus steady-state and unsteady-state numerical simulations were carried out. The effect of the high temperature steam mass fraction and the distribution of steam at the inlet boundary on the aerodynamic stability of a two-stage low-speed axial compressor was investigated. From the simulation results, we found that high temperature steam ingestion has an adverse effect on the low-speed axial compressor. The larger the steam mass fraction is, the greater the impact of the steam ingestion on the stability boundary and stall margin will be. When the steam mass fraction is equal to 0.35 and 0.7%, the stability margin decreases from 36.07 to 29.72% and 28.05%, respectively. The distribution of steam at the inlet boundary will change the performance and stability. When the steam ingestion range is less than 90°, the steam ingestion area increases and the stability margin will decrease gradually. After 90°, the stability margin is almost unchanged. The difference between the calculated and experimental values of the stability margin reduction caused by steam ingestion is 0.87%. In addition, with the ingestion of high temperature steam, the blockage in the corresponding passages is intensified and the loss is increased, which leads to the occurrence of the stall in advance. It is evident that steam ingestion has a significant impact on compressor stability, ensuring that the steam mass fraction and steam ingestion range are close to the actual value.

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