Effect of Blade Aspiration Slot Configuration on the Aerodynamic Performance of a Highly Loaded Aspirated Compressor Cascade

2017 ◽  
Author(s):  
Longxin Zhang ◽  
Le Cai ◽  
Bao Liu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Control Method ◽  
Active Flow Control ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Flow Path ◽  
Compressor Cascade ◽  
Flow Loss ◽  
Highly Loaded

As a promising active flow control method, boundary layer suction (BLS) can be used to enhance the aerodynamic performance of the highly-loaded compressor effectively, and due to this reason, extensive studies have been carried out on it. However, contrast to those abundant studies focusing on the flow control effects of BLS, little attention has been paid on the design method of the aspiration flow path. This work presents a 3-D steady numerical simulation on a highly-loaded aspirated compressor cascade. The aspiration slot is implemented at its best location based on the previous experimental studies and the aspiration flow rate is fix to 1.5% of the inlet massflow. The plenum configuration follows the blade shape and remains unchanged. One-side-aspiration manner is adopted to simplify the aspiration devices. Two critical geometry parameters, slot angle and slot width, are varied to study the effects of blade aspiration slot configuration on the cascade loss, radial distribution of the aspiration flow rate and inner flow structures within the aspiration flow path. Results show that the slot configuration does affect the cascade performance. In comparison with the throughflow performance, it is especially true once the flow loss caused by the aspiration flow path is also taken into account, and higher flow loss will be generated within the aspiration flow path if an inappropriate scheme is adopted. In the present investigation, apart from the cases with larger negative slot angle, a wider slot is more preferable to a narrower one, since it could enhance the aspiration capacity near the endwall regions and lower the dissipation loss within the aspiration flow path. In terms of the slot angle, a larger negative value, i.e., the slot direction more aligned with the incoming flow, is not beneficial to improve the throughflow performance, while concerning the flow loss yield by the aspiration flow path, a proper negative slot angle is always optimal.

Numerical Study of Unsteady Pulsed Suction through Endwall Bleed Holes in a Highly Loaded Compressor Cascade

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Hongxin Zhang ◽  
Shaowen Chen ◽  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Numerical Study ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Skew Angle ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Parameters ◽  
Suction Flow ◽  
Highly Loaded

AbstractUnsteady pulsed suction (UPS) was applied as an unsteady flow control (UFC) technique in a certain highly loaded compressor cascade to control the flow separations. Only two bleed holes symmetrically mounted on the endwalls (one on the upper endwall and another on the lower endwall) were set up to achieve steady constant suction (SCS) and UPS. The improvements in aerodynamic performance by SCS and UPS under different time-averaged suction flow rates are firstly investigated and compared. The related unsteady aerodynamic parameters of UPS such as excitation frequency, excitation location, pitch angle, and skew angle are discussed and analyzed in detail. The results show that UPS can provide a better flow control effect than SCS with the same time-averaged dimensionless suction flow rate in the control of flow separation. The aerodynamic performance of compressor cascades can be significantly enhanced by UPS when unsteady aerodynamic parameters are in their optimum ranges. Based on the optimum parameters for UPS, the total pressure loss coefficient is reduced by 19 % only with the time-averaged dimensionless suction flow ratems=0.4 %.

Experimental Investigation of Endwall and Suction Side Blowing in a Highly Loaded Compressor Stator Cascade

2010 ◽  
Author(s):  
Daniel Nerger ◽  
Horst Saathoff ◽  
Rolf Radespiel ◽  
Volker Gu¨mmer ◽  
Carsten Clemen
Keyword(s):  
Experimental Investigation ◽  
Flow Control ◽  
Control Method ◽  
Active Flow Control ◽  
Pressure Rise ◽  
Suction Side ◽  
Spanwise Direction ◽  
Flow Power ◽  
Active Flow ◽  
Highly Loaded

The following paper describes an experimental investigation of a highly loaded stator cascade with a pitch to chord ratio of t/l = 0.6. Experiments without as well as with active flow control by means of endwall and suction side blowing were conducted. Five-hole-probe measurements in pitchwise and spanwise direction as well as endwall oil flow visualizations were carried out in order to determine the performance of the cascade and to analyze the flow phenomena occuring. To quantify the effectivity of the active flow control method, taking the additional energy input into account, corrected losses and an efficiency, which relates the difference of flow power deficit with and without active flow control to the flow power of the blowing jet itself, were evaluated. Even though an increase of static pressure rise could be achieved, a decrease of the total pressure losses was possible for a few operating points only.

scholarly journals Experimental and numerical results of active flow control on a highly loaded stator cascade

2011 ◽  
Vol 225 (7) ◽  
pp. 907-918 ◽  
Author(s):  
M Hecklau ◽  
C Gmelin ◽  
W Nitsche ◽  
F Thiele ◽  
A Huppertz ◽  
...  
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Numerical Results ◽  
Pressure Probe ◽  
Compressor Cascade ◽  
Time Resolved ◽  
Inlet Velocity ◽  
Wide Range ◽  
Active Flow ◽  
Highly Loaded

This article presents experimental and numerical results for a compressor cascade with active flow control. Steady and pulsed blowing has been used to control the secondary flow and separation characteristics of a highly loaded controlled diffusion airfoil. Investigations were performed at the design incidence for blowing ratios from approximately 0.7 to 3.0 (jet-to-inlet velocity) and a Reynolds number of 840 000 (based on axial chord and inlet velocity). Detailed flow field data were collected using a five-hole pressure probe, pressure taps on the blade surfaces, and time-resolved Particle Image Velocimetry. Unsteady Reynolds-averaged Navier–Stokes simulations were performed for a wide range of flow control parameters. The experimental and numerical results are used to understand the interaction between the jet and the passage flow. The benefit of the flow control on the cascade performance is weighted against the costs of the actuation by introducing an efficiency which takes the presence of the jets into account.

Numerical Investigation of a Sweeping Jet Actuator for Active Flow Control in a Compressor Cascade

2018 ◽  
Author(s):  
Qinghe Meng ◽  
Shaowen Chen ◽  
Weihang Li ◽  
Songtao Wang
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Control Method ◽  
Fluid Dynamic ◽  
Active Flow Control ◽  
Secondary Flows ◽  
Compressor Cascade ◽  
Skew Angle ◽  
Aerodynamic Loss ◽  
Active Flow

Sweeping Jet Actuator (SJA) was introduced as a potential active flow control method for reducing three-dimension (3D) flow separations in a compressor cascade. Unlike some other actuators, SJA needs no valves or moving parts to convert its steady compressed air source into sweeping jets that oscillates from side to side through the millimeter-sized outlet nozzle. The rather simple and small structure makes it possible to place SJA into the blades. In this study, a 3D numerical simulation using unsteady RANS codes was conducted to investigate the effects of SJA on the flow pattern and the aerodynamic loss mechanism in a compressor cascade. Firstly, the reliability of a commercial Computational Fluid Dynamic (CFD) code was validated and the computed results showed good agreements with experimental data from the literature. Secondly, some possible affecting factors, such as actuating pressure, position of SJA exit and jet skew angle, were analyzed and discussed in detail. Moreover, the effectiveness of active flow control under different locations and stream directions of SJA was studied for obtaining a further understanding of the mechanism of SJA for controlling flow separations. In addition, the generation and interaction of internal secondary flows in the compressor cascade were also investigated, and the oscillating jet process of SJA was presented. The numerical results indicate that using SJA delays effectively the corner flow separation, thus decreases the aerodynamic loss of the compressor cascade. For the optimum scheme within the present research, the reduction of overall time-averaged total pressure loss coefficient achieves about 5.6% compared with the original case without SJA. The streamwise position of SJA has a more remarkable influence in improving performance than the other SJA schemes. The considerable improvements of flow separation in the corner region is considered to be one of the main reasons in overall performance increase.

Active Flow Control Concepts on a Highly Loaded Subsonic Compressor Cascade: Résumé of Experimental and Numerical Results

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Christoph Gmelin ◽  
Vincent Zander ◽  
Martin Hecklau ◽  
Frank Thiele ◽  
Wolfgang Nitsche ◽  
...  
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Suction Side ◽  
Numerical Results ◽  
Pressure Probe ◽  
Control Parameters ◽  
Compressor Cascade ◽  
Wide Range ◽  
Active Flow ◽  
Highly Loaded

This paper presents experimental and numerical results for a highly loaded, low speed, linear compressor cascade with active flow control. Three active flow control concepts employing steady jets, pulsed jets, and zero mass flow jets (synthetic jets) are investigated at two different forcing locations: at the end walls and the blade suction side. Investigations are performed at the design incidence for jet-to-inlet velocity ratios of approximately 0.7 to 3.0 and two different Reynolds numbers. Detailed flow field data are collected using a five-hole pressure probe, pressure tabs on the blade surfaces, and time-resolved particle image velocimetry. Unsteady Reynolds-Averaged Navier-Stokes simulations are performed for a wide range of flow control parameters. The experimental and numerical results are used to understand the interaction between the jet and the passage flow. Variation of jet amplitude, forcing frequency and blowing angle of the different control concepts at both locations allows determination of beneficial control parameters and offers a comparison between similar control approaches. This paper combines the advantages of an expensive yet reliable experiment and a fast but limited numerical simulation. Excellent agreement in control effectiveness is found between experiment and simulation.

A Combined Application of Negative Bowed Blade and Endwall Unsteady Pulsed Holed Suction in a Highly Loaded Compressor Cascade

2018 ◽  
Author(s):  
Shaowen Chen ◽  
Hongxin Zhang ◽  
Qinghe Meng ◽  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Flow Control ◽  
Flow Separation ◽  
Flow Behavior ◽  
Excitation Frequency ◽  
Aerodynamic Performance ◽  
Flow Ratio ◽  
Compressor Cascade ◽  
Aero Engine ◽  
Suction Flow ◽  
Highly Loaded

With the increasing continually of blade load, a serious three-dimensional (3D) unsteady flow separation is caused in the design of modern advanced aero-engine compressor. The flow separation has a strong influence on the aerodynamic behavior of the flow in the compressor passage such as reducing the pressure rise capability and overall efficiency, and even resulting in stall and surge. Consequently, it is very necessary to apply some effective techniques for suppressing the 3D flow separation in order to improve the aerodynamic performance of aero-engine compressors. The endwall unsteady pulsed holed suction (EUPHS) is first developed. Additionally, the negative bowed blade is a convention passive flow control method. It can make the flow of the midspan move toward the endwall by changing the radial pressure distribution and improve flow behavior of the midspan. Therefore, with the aim of further improving the aerodynamic performance and flow behavior, the EUPHS combined with the negative bowed blade as a new promising compound flow control (CFC) technique is proposed. In this study, only two bleeding holes on the endwalls (one on the upper endwall and another on the lower endwall) are used to achieve suction in a highly loaded compressor cascade. The improvements in aerodynamic performance by endwall steady constant holed suction (ESCHS), EUPHS and CFC are investigated and compared firstly. Some related parameters such as suction-to-inlet time-averaged suction flow ratio and excitation frequency are also discussed and analyzed in detail. The results show that CFC has more potential advantages than ESCHS and EUPHS in reducing the total pressure loss coefficient and is a promising flow control technology to further enhance aerodynamic performance. Based on the optimal suction-to-inlet time-averaged suction flow ratio and excitation frequency, the total pressure loss coefficients for CFC are reduced by 17.7%.

Unsteady RANS Simulations of a Highly Loaded Low Aspect Ratio Compressor Stator Cascade With Active Flow Control

2010 ◽  
Author(s):  
Christoph Gmelin ◽  
Mathias Steger ◽  
Frank Thiele ◽  
Andre´ Huppertz ◽  
Marius Swoboda
Keyword(s):  
Aspect Ratio ◽  
Flow Control ◽  
Active Flow Control ◽  
Pressure Rise ◽  
Suction Side ◽  
Synthetic Jet ◽  
Compressor Cascade ◽  
Low Aspect Ratio ◽  
Rans Simulations ◽  
Highly Loaded

A highly loaded compressor cascade is analyzed by means of time-resolved 3D RANS simulations. Due to the low aspect ratio of the cascade, strong three-dimensional effects emerge, such as large corner vortices and trailing edge separation at the midspan. The feasibility of the simulation using a commercial software and the applicability of controlling the separated regions using zero net mass flux synthetic jets is analyzed. The work includes two control concepts that are investigated separately. One aims to affect the secondary flow emerging from the sidewalls via actuation at the cascade casing walls. The other aims to reattach the separated flow to the blade suction side using an actuator on the blade. Beneficial flow control parameters characterizing a synthetic jet are determined for both locations by a systematic variation. Special attention is drawn to the global efficiency of the stator cascade by means of total pressure loss and pressure rise.

Separation Control by Slot Jet in a Critically Loaded Compressor Cascade

2018 ◽  
Vol 35 (3) ◽  
pp. 229-239 ◽  
Author(s):  
Jiaguo Hu ◽  
Rugen Wang ◽  
Peigen Wu ◽  
Chen He
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Suction Side ◽  
Jet Flow ◽  
Compressor Cascade ◽  
Control Effect ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Flow Loss ◽  
Great Pressure

Abstract Separation in compressor cascade triggers flow loss and instability. This paper presents a passive flow control method by introducing a slot into the blade. The slot induces self-adapted jet, while the jet flow is used to suppress cascade’s separation. To study the flow control effect, experiments were conducted and flow field details were given by validated numerical simulations. The results show that a well-designed slot carries adequate jet airflow from pressure side (PS) to suction side (SS) due to the great pressure fall between the two sides. The jet airflow delays suction side separation within specific incidence angles, so the performance of cascade achieves considerable improvements. It enables to be concluded that the slot carries jet flow to SS separation zone, and then the self-adapted jet flow re-energizes low momentum fluid and suppresses vortices in the separation which are negative to the cascade flow.

Pulsed suction control in a highly-loaded compressor cascade with low suction flow rates

2021 ◽  
pp. 1-39
Author(s):  
Hongxin Zhang ◽  
Shaowen Chen
Keyword(s):  
Flow Rate ◽  
Flow Separation ◽  
Aerodynamic Performance ◽  
Compressor Cascade ◽  
Control Effect ◽  
Suction Force ◽  
Flow Rates ◽  
Suction Control ◽  
Suction Flow ◽  
Highly Loaded

Abstract The influence of pulsed suction (PS) on flow separation and aerodynamic performance in a highly loaded compressor cascade is experimentally studied herein. The excitation frequency is investigated as it determines the effectiveness of PS in flow control. Low suction flow rates are examined to analyze the potential of PS in providing a satisfactory cascade performance. For comparison, the corresponding parameters of steady continuous suction (SCS) are studied as well. Oil flow visualizations and steady and unsteady pressure data are used to characterize the control effects of SCS and PS. The experimental results validate the efficacy of PS in controlling flow separation, even at a reduced suction flow rate of 0.1%. It suppresses passage vortex is suppressed, improving aerodynamic performance. PS provides a better control effect than SCS at different excitation parameters, which can be attributed to twofold main reasons: first, at the same suction flow rate, PS has a larger suction momentum than SCS during the suction phase, resulting in a stronger suction force and having a more profound effect on the flow characteristics; and second, owing to the introduction of pulsed excitation to the suction, PS creates additional vortex structures that energize the boundary layer by transporting high momentum free-stream fluid near the wall. PS is also effective at a higher incidence angle, but its control effect is reduced.

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