Coupling method of stability enhancement based on casing treatments in an axial compressor

2019 ◽  
Vol 95 ◽  
pp. 105449 ◽  
Author(s):  
Wei Wang ◽  
Jin-ling Lu ◽  
Xing-qi Luo ◽  
Wu-li Chu
Keyword(s):  
Axial Compressor ◽  
Coupling Method ◽  
Stability Enhancement ◽  
Casing Treatments

scholarly journals Oscillatory Tip Leakage Flows and Stability Enhancement in Axial Compressors

2018 ◽  
Vol 2018 ◽  
pp. 1-14
Author(s):  
Feng Lin ◽  
Jingyi Chen
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Momentum Balance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Stability Enhancement ◽  
Tip Leakage Flows ◽  
Casing Treatments

Rotating stall axial compressor is a difficult research field full of controversy. Over the recent decades, the unsteady tip leakage flows had been discovered and confirmed by several research groups independently. This paper summarizes the research experience on unsteady tip leakage flows and stability enhancement in axial flow compressors. The goal is to provide theoretical bases to design casing treatments and tip air injection for stall margin extension of axial compressor. The research efforts cover (1) the tip flow structure at near stall that can explain why the tip leakage flows go unsteady and (2) the computational and experimental evidences that demonstrate the axial momentum playing an important role in unsteady tip leakage flow. It was found that one of the necessary conditions for tip leakage flow to become unsteady is that a portion of the leakage flow impinges onto the pressure side of the neighboring blade near the leading edge. The impediment of the tip leakage flow against the main incoming flow can be measured by the axial momentum balance within the tip range. With the help of the theoretical progress, the applications are extended to various casing treatments and tip air recirculation.

Injection profile effects on low speed axial compressor stability enhancement

2011 ◽  
Vol 25 (6) ◽  
pp. 1501-1507 ◽  
Author(s):  
Hyung-Soo Lim ◽  
Hyo-Jo Bae ◽  
Young-Cheon Lim ◽  
Seung-Jin Song ◽  
Shin-Hyoung Kang ◽  
...  
Keyword(s):  
Axial Compressor ◽  
Low Speed ◽  
Stability Enhancement

scholarly journals Effects of Endwall Suction and Blowing on Compressor Stability Enhancement

1989 ◽  
Author(s):  
N. K. W. Lee ◽  
E. M. Greitzer
Keyword(s):  
Flow Injection ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Primary Objective ◽  
Stall Margin ◽  
Casing Treatment ◽  
Blade Row ◽  
Stall Margin Improvement ◽  
Stability Enhancement ◽  
Suction And Blowing

An experimental investigation was carried out to examine the effects on stall margin of flow injection into, and flow removal out of, the endwall region of an axial compressor blade row. A primary objective of the investigation was clarification of the mechanism by which casing treatment (which involves both removal and injection) suppresses stall in turbomachines. To simulate the relative motion between blade and treatment, the injection and removal took place through a slotted hub rotating beneath a cantilevered stator row. Overall performance data and detailed (time-averaged) flowfield measurements were obtained. Flow injection and removal both increased the stalling pressure rise, but neither was as effective as the wall treatment. Removal of high blockage flow is thus not the sole reason for the observed stall margin improvement in casing or hub treatment, as injection can also contribute significantly to stall suppression. The results also indicate that the increase in stall pressure rise with injection is linked to the streamwise momentum of the injected flow, and it is suggested that this should be the focus of further studies.

Influencing Parameters of Tip Blowing Interacting With Rotor Tip Flow

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Cyril Guinet ◽  
André Inzenhofer ◽  
Volker Gümmer
Keyword(s):  
Geometric Model ◽  
Axial Compressor ◽  
Axial Flow ◽  
Navier Stokes ◽  
Axial Position ◽  
Design Parameters ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Casing Treatments

The design space of axial-flow compressors is restricted by stability issues. Different axial-type casing treatments (CTs) have shown their ability to enhance compressor stability and to influence efficiency. Casing treatments have proven to be effective, but there still is need for more detailed investigations and gain of understanding for the underlying flow mechanism. Casing treatments are known to have a multitude of effects on the near-casing 3D flow field. For transonic compressor rotors, these are more complex, as super- and subsonic flow regions alternate while interacting with the casing treatment. To derive design rules, it is important to quantify the influence of the casing treatment on the different tip flow phenomena. Designing a casing treatment in a way that it antagonizes only the deteriorating secondary flow effects can be seen as a method to enhance stability while increasing efficiency. The numerical studies are carried out on a tip-critical rotor of a 1.5-stage transonic axial compressor. The examined recirculating tip blowing casing treatment (TBCT) consists of a recirculating channel with an air off-take above the rotor and an injection nozzle in front of the rotor. The design and functioning of the casing treatment are influenced by various parameters. A variation of the geometry of the tip blowing, more specifically the nozzle aspect ratio, the axial position, or the tangential orientation of the injection port, was carried out to identify key levers. The tip blowing casing treatment is defined as a parameterized geometric model and is automatically meshed. A sensitivity analysis of the respective design parameters of the tip blowing is carried out on a single rotor row. Their impact on overall efficiency and their ability to improve stall margin are evaluated. The study is carried out using unsteady Reynolds-averaged Navier–Stokes (URANS) simulations.

Structural Analysis of an Auxetic Casing Structure Incorporating Tip Blowing Casing Treatment Modification

2019 ◽  
Author(s):  
Tobias Schmidt ◽  
Jan Lorenz ◽  
Volker Gümmer ◽  
Andreas Hupfer
Keyword(s):  
Axial Compressor ◽  
Local Stress ◽  
Maximum Load ◽  
Element Analysis ◽  
Treatment Modification ◽  
Casing Treatment ◽  
Compressor Design ◽  
Stress Levels ◽  
Aero Engines ◽  
Casing Treatments

Abstract In axial compressor design for aero engines high system efficiency and operational stability are two main objectives. Both depend on clearance-induced losses. Previous investigations at the Institute have resulted in a passive clearance controlled compressor design using additively manufactured auxetic casing structures. The extension to an active clearance controlled device to keep an approximately constant tip gap ratio during the entire flight mission is currently investigated. Constructive on these deliverables, the implementation of tip blowing casing treatment modification in a double-walled compressor casing including an auxetic inner structure is covered in this work and studied for maximum load conditions by means of Finite Element Analysis. The idea to supplement the current auxetic casing construction with casing treatment modification emerges from the aspiration to generate further stability improvements in the high-pressure domain and the exploitation of the design freedom provided by additive manufacturing. Key issues addressed in this work by conducting parameter studies are casing treatment positioning and corresponding structural correlations depending on circumferential quantity. The evaluation section concentrates mainly on the calculated stress level associated with tip blowing casing treatments because this value is crucial for prospective fatigue predictions. In order to compare the results, the auxetic casing structure without casing treatment modification serves as reference. Promising solutions for local stress reductions are also proposed and discussed. From a structural mechanics perspective, the casing treatment modification generates very high and comparable notch stress levels at each position. Placing the casing treatments at the framework of the auxetic cells and splitting the inner casing ring results in tolerable stress levels.

Compressor Stability Enhancement Using Discrete Tip Injection

2000 ◽  
Vol 123 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Kenneth L. Suder ◽  
Michael D. Hathaway ◽  
Scott A. Thorp ◽  
Anthony J. Strazisar ◽  
Michelle B. Bright
Keyword(s):  
Axial Velocity ◽  
High Speed ◽  
Axial Compressor ◽  
Flow Coefficient ◽  
Navier Stokes ◽  
Injection Velocity ◽  
Compressor Rotor ◽  
Annulus Flow ◽  
Tip Injection ◽  
Stability Enhancement

Mass injection upstream of the tip of a high-speed axial compressor rotor is a stability enhancement approach known to be effective in suppressing stall in tip-critical rotors. This process is examined in a transonic axial compressor rotor through experiments and time-averaged Navier-Stokes CFD simulations. Measurements and simulations for discrete injection are presented for a range of injection rates and distributions of injectors around the annulus. The simulations indicate that tip injection increases stability by unloading the rotor tip and that increasing injection velocity improves the effectiveness of tip injection. For the tested rotor, experimental results demonstrate that at 70 percent speed the stalling flow coefficient can be reduced by 30 percent using an injected massflow equivalent to 1 percent of the annulus flow. At design speed, the stalling flow coefficient was reduced by 6 percent using an injected massflow equivalent to 2 percent of the annulus flow. The experiments show that stability enhancement is related to the mass-averaged axial velocity at the tip. For a given injected massflow, the mass-averaged axial velocity at the tip is increased by injecting flow over discrete portions of the circumference as opposed to full-annular injection. The implications of these results on the design of recirculating casing treatments and other methods to enhance stability will be discussed.

Aerodynamic Design of Abradable Liners With Integrated Endwall Treatments for Axial Compressor Rotors

2013 ◽  
Author(s):  
Tobias Mayenberger ◽  
Hans-Peter Kau ◽  
Giovanni Brignole
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Axial Compressor ◽  
Mechanical Stresses ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Aerodynamic Design ◽  
Liner Material ◽  
Blade Tip ◽  
Casing Treatments

In this study endwall treatments, which are integrated into an abradable liner, are used to reduce the liner solidity, defined by the volumetric proportion between endwall treatments and solid casing. Consequently the milled off amount of liner material during the rubbing process is decreased. The mechanical stresses in the rotor blades are thus supposed to be reduced, so that liner materials with higher strength can be used or additional blade tip coatings are dispensable. Accordingly, the purpose of the present study was to develop geometries of endwall treatments, which reduce the liner solidity as much as possible without degrading the stage performance of the test compressor. The focus of the work lies exclusively on the aerodynamics. Investigations were made by steady and unsteady computational fluid dynamics on a transonic single stage axial compressor with two different tip clearance sizes (0.64%/1.28% span). The developed configurations resemble casing treatments, comparable to axial slots and circumferential grooves, which are adapted to the specific tasks of liners. Solidity could be reduced by as much as 29% with negligible efficiency degradation for small tip gaps and increased efficiencies for large tip clearances.

Optimization of Slots-Groove Coupled Casing Treatment for an Axial Transonic Compressor

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Guoming Zhu ◽  
Bo Yang
Keyword(s):  
Pareto Front ◽  
Leading Edge ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Injection Flow ◽  
Optimization Stage ◽  
Stability Enhancement ◽  
Optimal Configurations ◽  
Casing Treatments

Abstract A multi-objective optimization of a coupled casing treatment (CCT) for an axial transonic compressor is performed in this study. The coupled casing treatment is the basis axial slots with a circumferential groove located at various positions along the slots. During the optimization stage, five important parameters to control the geometry are used as the optimal variables. The stall margin and the peak efficiency are selected as the optimal objectives. Non-dominated sorting genetic algorithm II coupled with radial basis function (RBF) approximation is used to search for Pareto-optimal solutions. Then, four optimal configurations are selected from Pareto-front for further analysis. As shown in the simulation results with and without the coupled casing treatments, the leakage flow is reenergized and the blocking region near the blade leading edge at rotor tip is decreased by the use of these structures under the low flowrate condition, which is the main reason for stability enhancement. Besides, a coupled casing treatment with the groove settled near the end of the basis slots have the potential to generate more injection flow and extend the operating range of compressor further.

Performance and Stability Enhancement of NASA Rotor 37 Applying Abradable Coating

2005 ◽  
Author(s):  
Behnam H. Beheshti ◽  
Bijan Farhanieh ◽  
Kaveh Ghorbanian ◽  
Joao A. Teixeira ◽  
Paul C. Ivey
Keyword(s):  
Flow Characteristics ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Compressors ◽  
Compressor Rotor ◽  
Abradable Coating ◽  
Blade Tip ◽  
Stability Enhancement

Improvements in sealing mechanism between the rotating and the stationary parts of a turbomachine can extensively reduce the endwall leakage flow. In this regard, abradable seals are incorporated into compressor and turbine blade-tip region. In a gas turbine, equipped with abradable seals, tip of the rotor blade is designed to cut into the material coating of the casing and to form a close fitted circumferential groove for the movement of the blade tip. As a result, the resistance to the leakage flow in the tip gap region increases due to smaller tip clearances (available without any rub-induced damages). Minimizing the tip clearance size can lead to an increase in performance and stability. This paper presents a numerical investigation of abradable coating as a means to seal the tip leakage flow in NASA Rotor 37, a transonic axial compressor rotor. In order to validate the multi block model used in the tip gap region, various flow characteristics are verified with the experimental data for smooth casing at a design clearance of 0.5% span. To have a better understanding of how an abradable seal affects the passage flow field, smooth casing and abradable coating are studied and results are compared for various models including two different incursion depth and width. Results indicate that the application of abradable coating in transonic axial compressors can efficiently improve the performance and stability.

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