Investigation of Recirculating Casing Treatment for Low-Pressure Ratio Mixed-Flow Micro-Compressor

2020 ◽  
Author(s):  
Kewei Xu ◽  
Gecheng Zha
Keyword(s):  
Pressure Ratio ◽  
Numerical Approach ◽  
Efficiency Loss ◽  
Stall Margin ◽  
Design Point ◽  
Casing Treatment ◽  
Final Design ◽  
Upstream Flow ◽  
Total Pressure Ratio ◽  
Good Agreement

Abstract This paper investigates the recirculating casing treatment (RCT) of a low total pressure ratio micro-compressor to achieve stall margin enhancement while minimizing the design point efficiency penalty. Three RCT injection and extraction configurations are studied, including combined slot-duct, ducts only, and slot only. The numerical approach is validated with a tested micro-compressor using RCT. A very good agreement is achieved between the predicted speedlines and the measured results. To minimize the design point efficiency loss, it is observed that the optimal location of extraction and injection is where the recirculated flow rate can be minimized at the design point. To maximize stall margin, extraction location should favor minimizing the tip blockage such as at the location where the tip flow separation of the baseline blade is fully developed. In addition, the slot configuration that generates pre-swirl to the upstream flow is beneficial to improve stall margin due to reduced incidence. The highest stall margin enhancement achieved is 9.49% with the slot geometry that has the extraction at the 62%C chordwise location, but has a design point efficiency loss of 1.9%. Overall, a small efficiency penalty of 0.6% at the design point is achieved for the final design with the stall margin increased by 6.2%.

scholarly journals Design and Optimization of Multiple Circumferential Casing Grooves Distribution Considering Sweep and Lean Variations on the Blade Tip

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2401
Author(s):  
Weimin Song ◽  
Yufei Zhang ◽  
Haixin Chen
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Distribution ◽  
Stall Margin ◽  
Design Point ◽  
Casing Treatment ◽  
Design And Optimization ◽  
Practical Engineering ◽  
Engineering Strategy ◽  
Blade Tip

This paper focuses on the design and optimization of the axial distribution of the circumferential groove casing treatment (CGCT). Effects of the axial location of multiple casing grooves on the flow structures are numerically studied. Sweep and lean variations are then introduced to the blade tip, and their influences on the grooves are discussed. The results show that the ability of the CGCT to relieve the blockage varies with the distribution of grooves, and the three-dimensional blading affects the performance of both the blade and the CGCT. Accordingly, a multi-objective optimization combining the CGCT design with the sweep and lean design is conducted. Objectives, including the total pressure ratio and the adiabatic efficiency, are set at the design point; meanwhile, the choking mass flow and the near-stall performance are constrained. The coupling between the CGCT and the blade is improved, which contributes to an optimal design point performance and a sufficient stall margin. The sweep and lean in the tip redistribute the spanwise and chordwise loading, which enhances the ability of the CGCT to improve the blade’s performance. This work shows that the present CGCT-blade integrated optimization is a practical engineering strategy to develop the working capacity and efficiency of a compressor blade while achieving the stall margin extension.

An Experimental Investigation About the Effect of the Partial Casing Treatment on a Transonic Axial-Flow Compressor Performance Under Inlet Distortion

2012 ◽  
Author(s):  
Maoyi Li ◽  
Wei Yuan ◽  
Xizhen Song ◽  
Yajun Lu ◽  
Zhiping Li ◽  
...  
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Peak Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Inlet Distortion ◽  
Flow Compressor ◽  
Total Pressure Ratio

The traditional annulus casing treatment often pays the price of lowered efficiency for improving the stall margin of a compressor under inlet distortion. In view of the unsymmetry of the inlet flow-field of compressors, partial casing treatment was used to control the flow in a transonic axial-flow compressor with arc-skewed-slots deployed at different circumferential positions under inlet distortion. The experimental results indicate that when the partial casing treatment is arranged on the undistorted and distorted sectors, the stall margin is enhanced by 8.02%, with the relative peak efficiency improved simultaneously by 2.143%, compared with the case of solid casing at 98% rotating speed. By contrast, the traditional casing treatment increases the stall-margin by 23.13%, but decreases the relative peak efficiency by 0.752%. By analyzing dynamic and static experimental data, the mechanism underlying the partial casing treatment was also studied in detail here. The disturbances of inlet flow were restrained by annulus casing treatment, nevertheless the total pressure ratio was decreased obviously in the distorted sector. As a result, the stall-margin is improved, but the relative peak efficiency is decreased too. When the partial casing treatment was arranged on the undistortded and distorted sectors, the stall disturbances was thereby restrained. So the stall margin was enhanced. In addition, the total pressure ratio was improved by the partial casing treatment in the distorted and transition sectors, and thus the relative peak efficiency was also increased markedly.

scholarly journals Aerodynamic Optimization Design of a Supersonic Compressor Rotor with High Pressure Ratio

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Cui Cui ◽  
Zhenggui Zhou ◽  
Endor Liu
Keyword(s):  
Shock Waves ◽  
Total Pressure ◽  
Optimization Design ◽  
Pressure Ratio ◽  
Strong Shock ◽  
Stall Margin ◽  
Design Point ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Total Pressure Ratio

Supersonic compressors have a high wheel speed and operational capability, which facilitate a high stage pressure ratio. However, the strong shock waves in the passage of a supersonic rotor and the interference between shock waves and boundary layers can lead to large flow loss and low efficiency. Moreover, the existing design of a high-load supersonic compressor has the problem of small stall margin. In this study, an automatic optimization method including 2D profile optimization and 3D blade optimization is proposed to achieve a high efficiency at the design point of a supersonic compressor rotor under the premise of reaching the desired mass flow rate and total pressure ratio. According to the analysis of flow near the stall point of the supersonic compressor rotor, the mechanism responsible for rotor tip stall is established, that is, the aerodynamic throat appeared inside the flow passage, reducing the ability of the blade tip to withstand back pressure, and the low-speed areas caused by the tip-leakage-vortex breakage and boundary layer separation reduced the flow capacity of the blade tip. Based on the reasons for rotor stall, three methods are proposed to improve the stall margin, which include increasing the exit radius of the upper meridian, forward sweep of the blade tip, and increasing the chord length of the blade tip. The above method is used to design a supersonic rotor with a total pressure ratio of 2.8, which exhibits an efficiency of 0.902 at the design point and a stall margin of 18.11%.

Numerical and Experimental Investigation As Applied to Effects of Labyrinth-Type Casing Treatments on Performance of High-Loaded Compressor First Stage

2018 ◽  
Author(s):  
V. I. Mileshin ◽  
V. V. Zhdanov ◽  
A. M. Petrovitchev
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Pressure Ratio ◽  
Turbulence Models ◽  
Lower Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Smooth Flow ◽  
Casing Treatments ◽  
Good Agreement

In connection with the development of a new family of high-pressure HPC with ultra-high pressure ratio and the number of stages 10–11, a special attention should be paid to the development of the first high-load stage, because compressor performance directly depends on its excellence. Despite the fact that the stage at nominal rotational speeds can have optimal performance, stall margins at intermediate rotational speeds can decrease because of a sizable IGV closure. One of the ways to increase stall margins is the use of labyrinth-type casing treatments. The Stage “A-1” studied in this work is a full-scale first stage in a six-stage high-pressure compressor (HPC) for a core demonstrator. The primary design task for the labyrinth-type casing treatment (CT) is to keep performance at design rotational speeds (n = 100%) or improve them, if possible, and increase stall margins at intermediate speeds (n = 70% and n = 80%). The labyrinth-type CT consisting of 3 circumferential grooves located above the middle of the blade chord projection is specially designed and manufactured for this stage. Our computations show that the use of the labyrinth-type CT leads to a shift of performance towards higher airflow and efficiency that is a good agreement with experimental data. An increase in stall margins without changes in efficiency is found by calculations, whereas the test, on the contrary, shows no influence on stall margins and an increase in efficiency by ∼1.5% (the same as at rated speeds). Both investigated turbulence models (SST and k-ε) do not provide good agreement with the experimental data. The SST model captures CT influence, but decreases stall margin. The k-ε model show agreement with the test in stall margin, but cannot capture CT influence. In addition, both models show lower efficiency compared with the experimental data. To verify the NUMECA Fine Turbo (version 11.1) mathematical model and numerical method, calculated and experimental characteristics of the Stage A-1 with a smooth flow passage and a labyrinth-type CT are compared. The NUMECA Autogrid 5 grid generator is used to build the grid.

scholarly journals Axial Flow Compressor Stability Enhancement: Circumferential T-Shape Grooves Performance Investigation

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 12
Author(s):  
Marco Porro ◽  
Richard Jefferson-Loveday ◽  
Ernesto Benini
Keyword(s):  
Vortex Breakdown ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Suction Side ◽  
Treatment Technique ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement

This work focuses its attention on possibilities to enhance the stability of an axial compressor using a casing treatment technique. Circumferential grooves machined into the case are considered and their performances evaluated using three-dimensional steady state computational simulations. The effects of rectangular and new T-shape grooves on NASA Rotor 37 performances are investigated, resolving in detail the flow field near the blade tip in order to understand the stall inception delay mechanism produced by the casing treatment. First, a validation of the computational model was carried out analysing a smooth wall case without grooves. The comparisons of the total pressure ratio, total temperature ratio and adiabatic efficiency profiles with experimental data highlighted the accuracy and validity of the model. Then, the results for a rectangular groove chosen as the baseline case demonstrated that the groove interacts with the tip leakage flow, weakening the vortex breakdown and reducing the separation at the blade suction side. These effects delay stall inception, improving compressor stability. New T-shape grooves were designed keeping the volume as a constant parameter and their performances were evaluated in terms of stall margin improvement and efficiency variation. All the configurations showed a common efficiency loss near the peak condition and some of them revealed a stall margin improvement with respect to the baseline. Due to their reduced depth, these new configurations are interesting because they enable the use of a thinner light-weight compressor case as is desirable in aerospace applications.

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.

Design of Casing Treatment on a Mixed-Flow Compressor

2017 ◽  
Author(s):  
Juan Du ◽  
Joerg R. Seume
Keyword(s):  
Pressure Ratio ◽  
Leading Edge ◽  
Area Ratio ◽  
Open Area ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Flow Compressor

Casing treatments (CTs) have been proved to beneficially affect the behavior of tip clearance flow and compressor stability. This paper presents the design of casing treatment for a mixed-flow compressor with a very small tip gap of 0.1mm. In the first part, the potential of applying two traditional types of casing treatments, i.e. circumferential grooves and axial slots, to enhance the stability of a mixed-flow compressor is investigated. The flow details in the reference compressor with smooth casing are examined first. It is found that a separating vortex is formed due to the reversed flow on the blade suction side near the rotor trailing edge at the near-stall point. It is supposed to be responsible for the decrease in total pressure ratio when the compressor approaches to stall. The numerical stall, i.e. the breakdown of the simulation, is initiated from the spillage of tip leakage flow over the rotor blade leading edge. The effect of circumferential grooves on the compressor performances is not remarkable. The implement of axial slots ameliorates the total pressure ratio and extend the flow range substantially, but with higher efficiency penalty than the circumferential grooves. The recirculation formed in the axial skewed slots eliminates the separation vortex near the trailing edge and suppresses the spillage of the tip leakage flow forward the rotor leading edge simultaneously. The axial skewed slots are further designed and optimized numerically by DoE (Design of Experiments). As DoE factors the axial length, the height, the open area ratio, and the number per blade passage of the slots are varied. Their effects on the two target values stall margin and polytropic efficiency are investigated. The plot of stall margin improvement (SMI) with a function of the peak efficiency improvement (PEI) indicates that the SMI changes reversely with the PE. There are two trends in the correlation curves of SMI with PE. For the configurations with the open area ratio of 20%, the SMI is changed from 9% to 23% with 1% decrease in PE by varying other three factors. For the CTs with the open area ratio of 60% the augment in SMI from 17.8% to 26.3% produces extra efficiency loss of 4.2%.

Transonic Compressor Blade Optimization Integrated With Circumferential Groove Casing Treatment

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Weimin Song ◽  
Yufei Zhang ◽  
Haixin Chen ◽  
Kaiwen Deng
Keyword(s):  
Pressure Ratio ◽  
Compressor Blade ◽  
Superior Performance ◽  
Aerodynamic Optimization ◽  
Stall Margin ◽  
Casing Treatment ◽  
Integrated Optimization ◽  
Transonic Compressor ◽  
Circumferential Groove ◽  
Blade Optimization

A compressor blade integrated with circumferential groove casing treatment (CGCT) is optimized in this study. A hybrid aerodynamic optimization algorithm that combines the differential evolution (DE) with a radial basis function (RBF) response surface is used for the multi-objective optimization via the computational fluid dynamics (CFD) analysis. The sweep and lean distributions are optimized to pursue the maximum total pressure ratio and adiabatic efficiency at the design point. Constraints on the choking mass flow rate and the near-stall compression ratio are imposed to ensure the off-design performance. The performance is improved much more with the blade-CGCT integrated optimization than with the blade-only optimization. The stall margin of the blade-only optimized blade with CGCT added as an afterthought can be even worse than the baseline blade. The CGCT-removal test for the blade-CGCT integrated optimization result further verifies that the superior performance of the blade-CGCT integrated optimization is obtained via optimizing the coupling between the effects of the sweep and lean on the blade loading and the effects of the CGCT on the flow blockage.

Effect of inlet distortion on the performance of axial transonic contra-rotating compressor

2016 ◽  
Vol 232 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Hanru Liu ◽  
Yangang Wang ◽  
Songchuan Xian ◽  
Wenbin Hu
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Tip Leakage ◽  
Inlet Distortion ◽  
Flow Mixing ◽  
Inflow Conditions ◽  
Total Pressure Ratio

The present paper numerically conducted full-annulus investigation on the effects of circumferential total pressure inlet distortion on the performance and flow field of the axial transonic counter-rotating compressor. Results reveal that the inlet distortion both deteriorates the performance of the upstream and downstream rotors resulting in reduction of total pressure ratio, efficiency and stall margin of the transonic contra-rotating compressor. Regarding the development of distortion inside compressor, the downstream rotor reinforces the air-flow mixing effects and, thus, attenuates the distortion intensity significantly. Under the distorted inflow conditions, the detached shockwave at the leading edge of downstream rotor interacts with the tip leakage flow and causes the blockage of the blades passage, which is one important reason for the transonic contra-rotating 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.

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