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.

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.

Analysis on slot-type casing treatment injection flow in an axial transonic compressor

2016 ◽  
Vol 230 (8) ◽  
pp. 792-804 ◽  
Author(s):  
Mingmin Zhu ◽  
Xiaoqing Qiang ◽  
Wensheng Yu ◽  
Jinfang Teng
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Direction ◽  
Stall Margin ◽  
Rotating Speed ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Injection Flow ◽  
Flow Through

The purpose of this work is to understand the properties of the injection flow through slots opening surfaces with steady and unsteady simulations. The feasibility of evaluating slot effectiveness by steady results is demonstrated. Transient features of injection flow are detailed investigated. Numerical investigations are carried out in a 1.5 axial transonic compressor stage at a specified rotating speed with seven kinds of slot-type casing treatments. Comparisons between steady/unsteady results show that differences of overall performance and injection mass flow rate are dependent on simulation methods, rather than slot configurations. Thus, correlation analysis by steady results of seven slot configurations is considered valid and reveals strong linear correlation between injection mass flow and stall margin improvements/efficiency drops. Therefore, it is practical to evaluate the effectiveness of a specific slot configuration in this compressor with steady results by calculating injection mass flow rate. Afterwards, unsteady simulations are performed with a specific configuration of arc-curve skewed slots. It is clarified that the dividing locations between suction/injection regions moves along the axial direction based on the relative rotor/slots location. Exchanging flow through slots opening surfaces displays periodic variations over time. The variation cycle for one single slot equals blade passing period T. For summation of mass flow through all slots, the cycle equals to T divided by slots number in one passage. The net flow rate through all opening surfaces is always less than zero during a blading passing period, i.e. injection mass flow rate is larger than suction flow all the time.

Stall Margin Improvement by Use of Casing Treatments

2013 ◽  
Author(s):  
Christian T. Pixberg ◽  
Heinz-Peter Schiffer ◽  
M. H. Ross ◽  
J. D. Cameron ◽  
S. C. Morris
Keyword(s):  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Clearance Flow ◽  
Beneficial Impact ◽  
Stall Margin Improvement ◽  
Blade Tip ◽  
Casing Treatments

The beneficial impact of casing treatments on the stall margin of tip-critical compressors has been proven many times. However, there is still no simple and general method to predict their actual effectiveness. The present work considers the axial velocity deficit that is generally observed at the blade tip. This so called tip-blockage is caused by the tip clearance flow. That is investigated for different configurations of the transonic compressor test facilities in Darmstadt and Notre Dame and the results are presented in this paper. Similar circumferential groove casing treatments were applied to different single-stage and 1.5-stage compressors. They all had a tip critical behavior in common, but exhibited different design philosophies. The effectiveness of similar casing treatments on different stages was observed. A new method for calculating tip-blockage is introduced based on compressor performance and the results of a through-flow tool. A direct link between blockage growth and stall margin improvement was found for circumferential grooves casing treatments. Additionally, the results of an axial slot casing treatment are taken into account.

Effect of Novel Casing Treatment on the Suppression of Stall Precursor in a Transonic Compressor

2014 ◽  
Author(s):  
Dakun Sun ◽  
Xiaofeng Sun ◽  
Xiaohua Liu ◽  
Feng Lin ◽  
Nie Chao Qun
Keyword(s):  
Perforated Plate ◽  
Area Ratio ◽  
Open Area ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Stall Margin Improvement ◽  
Stall Precursor ◽  
Casing Treatments

A kind of novel casing treatment is proposed to realize stall margin enhancement by suppressing stall precursor in turbomachinery. In view of its different configuration and mechanism, such casing treatment is named as stall precursor-suppressed casing treatment in the present work, or SPS casing treatment for short. In the present work, the experiments of SPS casing treatment are conducted in a transonic compressor J69 Rotor/Stage. The SPS casing treatment which consists of a backchamber and a perforated plate is designed according to a proposed theoretical model. It is noted that the open area ratio of the casing treatment is only 4–12%, which is much smaller than traditional casing treatments with over 50% open area ratio. The tests show that the SPS casing treatment can improve the stall margin by 8–12% for J69 Rotor, and 4–12% for J69 Stage. Meanwhile, the mechanism of stall margin improvement with such casing treatment will be revealed in this investigation. Comparing with the evolution of the precursors without casing treatments, the propagation of the stall inception waves will be suppressed and the non-linear development of the stall process will be delayed under the casing treatment case.

CFD Investigation on the Circumferential Grooves Casing Treatment of Transonic Compressor

2008 ◽  
Author(s):  
Xudong Huang ◽  
Haixin Chen ◽  
Song Fu
Keyword(s):  
Vortex Breakdown ◽  
Leading Edge ◽  
Tip Clearance ◽  
Groove Width ◽  
Mechanism Analysis ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Edge Separation

The performance of NASA Rotor 37 with Circumferential Grooves Casing Treatment (CGCT) is studied with an in-house CFD code NSAWET. Based on the stall mechanism analysis, a number of CGCT configurations have been proposed and numerically tested. The computation results show that the stall mechanisms are strongly related with the width of tip clearance. With a small tip clearance, the stall process is dominated by the trailing edge separation, while the leading edge tip leakage vortex breakdown induced blockage causes stall in a large tip clearance configuration. Circumferential grooves at appropriate axial locations can be beneficial to the stall margin in these two types of stall processes. The effects of the groove width and depth are presented. The mechanisms of CGCT for different tip clearances are also discussed.

Axial-Slot Casing Treatments Improve the Efficiency of Axial Flow Compressors: Aerodynamic Effects of a Rotor Redesign

2013 ◽  
Author(s):  
J. Anton Streit ◽  
Frank Heinichen ◽  
Hans-Peter Kau
Keyword(s):  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Negative Effects ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Flow Phenomena ◽  
Casing Treatments

A state-of-the-art transonic compressor rotor has a distinct potential for increased efficiency if modified for improved interaction with an axial-slot type casing treatment. Reducing the number of blades and thus the surface lowers friction losses but increases tip clearance effects and deteriorates the stall margin due to the higher aerodynamic blade loading. The latter two negative effects can be compensated for by the casing treatment, thus restoring the required stall margin and gaining an overall reduction of losses. For the specific compressor rotor under investigation, the potential in polytropic efficiency is as high as 0.7%. The present study was performed using time-accurate CFD (URANS) simulations. Both the reference rotor as well as the modified design are analyzed regarding their interaction with the casing treatment. The traceability of the conclusions is assured by interpreting the detailed flow phenomena. The newly designed rotor is found to be favorably influenced by the casing treatment at design operating conditions whilst the reference only benefits at throttled operating points. Casing treatments are commonly used to broaden the operating range of existing compressors without changing the design of the compressor rotor itself. This study aims to show the possible transformation of this potential in the stall margin into efficiency at design operating conditions by implementing an appropriate rotor design.

Influencing Parameters of a Tip Blowing Interacting With Rotor Tip Flow

2015 ◽  
Author(s):  
Cyril Guinet ◽  
André Inzenhofer ◽  
Volker Gümmer
Keyword(s):  
Geometric Model ◽  
Axial Compressor ◽  
Axial Flow ◽  
Axial Position ◽  
Design Parameters ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Flow Phenomena ◽  
Casing Treatments

The design space of axial-flow compressors is restricted by stability issues. Different axial-type casing treatments 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, which 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 is 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 is evaluated. The study is carried out using URANS simulations.

Application of Casing Circumferential Grooves for Improved Stall Margin in a Transonic Axial Compressor

2002 ◽  
Author(s):  
D. C. Rabe ◽  
C. Hah
Keyword(s):  
Incidence Angle ◽  
Axial Compressor ◽  
Numerical Procedure ◽  
Leading Edge ◽  
Navier Stokes ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Flow Mechanisms ◽  
Groove Configurations

Experimental and numerical investigations were conducted to study the fundamental flow mechanisms of circumferential grooves in the casing of a transonic compressor and their influence on compressor stall margin. Three different groove configurations were tested in a highly loaded transonic compressor. Experimental results show that circumferential grooves increase the stall margin of the compressor at the tested operating condition. Grooves with a much smaller depth than conventional designs are shown to be similarly effective in increasing the stall margin. Steady-state Navier-Stokes analyses were performed to study flow structures associated with each casing treatment. The numerical procedure calculates the overall effects of the circumferential grooves correctly. Detailed investigation of calculated flow fields indicates that losses are generated by interaction between the main passage flow and flow exiting the grooves. The grooves increase the stall margin by reducing the flow incidence angle on the pressure side of the leading edge, despite an overall increase in the endwall boundary layer thickness. This is due to complex interaction of the main passage flow with the additional radial and tangential flows created by the grooves.

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.

Effect of Airfoil Vortex Generator on the Performance and Stability of a Transonic Axial Compressor

2021 ◽  
Author(s):  
Subbaramu Shivaramaiah ◽  
Mahesh K. Varpe
Keyword(s):  
Pressure Ratio ◽  
Research Work ◽  
Vortex Generator ◽  
Leading Edge ◽  
Leakage Flow ◽  
Compressor Stage ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Tip Leakage ◽  
Transonic Compressor

Abstract In the present research work, effect of airfoil vortex generator on performance and stability of transonic compressor stage is investigated through CFD simulations. In turbomachines vortex generators are used to energize boundary and generated vortex is made to interact with tip leakage flow and secondary flow vortices formed in rotor and stator blade passage. In the present numerical investigation symmetrical airfoil vortex generator is placed on rotor casing surface close to leading edge, anticipating that vortex generated will be able to disturb tip leakage flow and its interaction with rotor passage core flow. Six different vortex generator configuration are investigated by varying distance between vortex generator trailing edge and rotor leading edge. Particular vortex generator configuration shows maximum improvement of stall margin and operating range by 5.5% and 76.75% respectively. Presence of vortex generator alters flow blockage by modifying flow field in rotor tip region and hence contributes to enhancement of stall margin. As a negative effect, interaction of vortex generator vortices and casing causes surface friction and high entropy generation. As a result compressor stage pressure ratio and efficiency decreases.

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