Experimental and Numerical Researches in a Four-Stage Low Speed Research Compressor Facility

Author(s):  
Mingmin Zhu ◽  
Xiaoqing Qiang ◽  
Zhenzhou Ju ◽  
Yuchen Ma ◽  
Jinfang Teng

Abstract The flow fields in rear stages of multi-stage axial compressor is difficult to measure in detail owing to the limited height and space. Thus, low speed research compressor (LSRC) facilities which are modelled from rear stages have been widely used to explore the internal flow fields and improve compressor design. A newly-designed vertical LSRC facility is established and put into used in Shanghai Jiao Tong University. The construction and design features of this LSRC facility are introduced in this paper. A cantilevered stage has been tested in this test rig. Compressor performance, inter-stage parameters distributions and contours are measured at design point and near stall point. Steady single passage simulations for four-stage compressor are carried out to validate numerical methods and further interpret the internal flow fields in test stages. This vertical LSRC facility consists of inlet guide vane (IGV) and four repeated stages with an external diameter of 1.5 meter and a rotating speed of 900 RPM. The third stage is the mainly tested one, while the first and second stages provide the inlet conditions and the fourth stage provides the outlet conditions. Complete measuring methods and systems are established for this newly-built LRSC facility. The measurements of overall performance and inter-stage flow fields are carried out for test stage with cantilevered stator rows. The simulation for four-stage compressor are also performed for cantilevered configuration. The results of steady single-passage simulation have a similar trend with experimental ones, in terms of overall performance and parameters distributions.

Author(s):  
Haohao Zhang ◽  
Haowan Zhuang ◽  
Jinfang Teng ◽  
Mingmin Zhu ◽  
Xiaoqing Qiang

A steady and unsteady numerical research is carried out to explore some effects of a specific non-axisymmetric tip clearance layout on the overall performance and stability of an axial compressor stage. For a 4-stage low-speed research compressor (LSRC) in Shanghai Jiao Tong University (SJTU), one-eighth annulus of the inlet guide vane and the first stage rotor was modeled for this study. After the validation for the uniform tip clearance case, a specific non-axisymmetric tip clearance layout is chosen from several random cases generated by the Gaussian Probabilistic Density Function method. Unsteady time-averaged results at the near stall condition show that the chosen non-axisymmetric layout can improve the isentropic efficiency by 1.3% and extend the stall margin by 4%. Detailed analyses on flow fields are carried out to interpret the performance improvement. Due to the circumferential layout of clearance sizes, the inlet mass flow and incidence are redistributed in both the radial and circumferential directions. It leads to blade loading and tip leakage flow varying with the tip clearance size. The quantification of blockage manifests that the blockage arising from the tip leakage flow is significantly alleviated in the non-axisymmetric layout, which leads to improvements in overall performance and stall margin. Transient flow fields at the rotor tip are also analyzed at the near stall condition. For the non-axisymmetric layout, low-momentum regions originating from larger clearance sizes oscillate and develop downstream in one blade passage period.


Author(s):  
Mario Ku¨nzelmann ◽  
Ralf Mu¨ller ◽  
Ronald Mailach ◽  
Konrad Vogeler

This paper introduces a new test case for compressor aerodynamics. The dataset is provided for the Dresden four-stage Low-Speed Research Compressor (LSRC), which was put into operation in 1995. The compressor consists of four identical stages, which are preceded by an inlet guide vane. The data set will be provided for the reference blading of the compressor with cantilevered stator vanes. This blading was developed on the basis of the profiles of a middle stage of a high-pressure compressor of a jet engine. This paper makes available the blading geometry as well as a variety of flow field measurement results. This includes the compressor map, selected pressure distributions and other results of flow field measurements with conventional techniques (e.g. Pitot probes, 5-hole probes). Furthermore different aspects of blade row interactions were addressed in this compressor within recent years. The periodical unsteady flow field within a selected rotor blade row was investigated using Laser-Doppler-Anemometry. Further results on the unsteady profile pressures and profile boundary layers will be provided. Supplementary, numerical results will be compared to the experiments. Results are available for several stages of the compressor and different operating points. With this test case a unique database for the aerodynamics in a multistage axial compressor will be provided that can be used for the validation of numerical codes.


Author(s):  
J. D. Hughes ◽  
G. J. Walker

Data from a surface hot-film array on the outlet stator of a 1.5 stage axial compressor are analyzed to look for direct evidence of natural transition phenomena. An algorithm is developed to identify instability waves within the Tollmien Schlichting (T-S) frequency range. The algorithm is combined with a turbulent intermittency detection routine to produce space∼time diagrams showing the probability of instability wave occurrence prior to regions of turbulent flow. The paper compares these plots for a range of blade loading, with free-stream conditions corresponding to the maximum and minimum inflow disturbance periodicity produced by inlet guide vane clocking. Extensive regions of amplifying instability waves are identified in nearly all cases. The implications for transition prediction in decelerating flow regions on axial turbomachine blades are discussed.


Author(s):  
Milan Banjac ◽  
Milan V. Petrovic ◽  
Alexander Wiedermann

This paper describes a new universal algebraic model for the estimation of flow deflection and losses in axial compressor inlet guide vane devices. The model deals with nominal flow and far-off-design operating conditions in connection with large stagger angle adjustments. The first part of the model considers deflection and losses in 2D cascades, taking into account the main cascade geometry parameters and operating conditions, such as Mach number and stagger adjustment. The second part of the model deals with additional deviation and losses due to secondary flow caused by the endwall viscous effects and by the trailing vortices. The model is developed for NACA65 airfoils, NACA63-A4K6 airfoils and airfoils having an NACA65 thickness distribution on a circular-arc camber line. It is suitable for application in 1D or 2D through-flow calculations for design and analysis cases. The development of the method is based on systematic CFD flow calculations for various cascade geometries and operating parameters. The comparison of correlation results with experimental data for several test cases shows good agreement.


1998 ◽  
Vol 120 (4) ◽  
pp. 695-704 ◽  
Author(s):  
G. J. Walker ◽  
J. D. Hughes ◽  
I. Ko¨hler ◽  
W. J. Solomon

The interaction between wakes of an adjacent rotor–stator or stator–rotor blade row pair in an axial turbomachine is known to produce regular spatial variations in both the time-mean and unsteady flow fields in a frame relative to the upstream member of the pair. This paper examines the influence of such changes in the free-stream disturbance field on the viscous losses of a following blade row. Hot-wire measurements are carried out downstream of the outlet stator in a 1.5-stage axial compressor having equal blade numbers in the inlet guide vane (IGV) and stator rows. Clocking of the IGV row is used to vary the disturbance field experienced by the stator blades; the influence on stator wake properties is evaluated. The magnitude of periodic fluctuations in ensemble-averaged stator wake thickness is significantly influenced by IGV wake-rotor wake interaction effects. The changes in time-mean stator losses appear marginal.


2021 ◽  
Author(s):  
Stefan D. Cich ◽  
J. Jeffrey Moore ◽  
Chris Kulhanek ◽  
Meera Day Towler ◽  
Jason Mortzheim

Abstract An enabling technology for a successful deployment of the sCO2 close-loop recompression Brayton cycle is the development of a compressor that can maintain high efficiency for a wide range of inlet conditions due to large variation in properties of CO2 operating near its dome. One solution is to develop an internal actuated variable Inlet Guide Vane (IGV) system that can maintain high efficiency in the main and re-compressor with varying inlet temperature. A compressor for this system has recently been manufactured and tested at various operating conditions to determine its compression efficiency. This compressor was developed with funding from the US DOE Apollo program and industry partners. This paper will focus on the design and testing of the main compressor operating near the CO2 dome. It will look at design challenges that went into some of the decisions for rotor and case construction and how that can affect the mechanical and aerodynamic performance of the compressor. This paper will also go into results from testing at the various operating conditions and how the change in density of CO2 affected rotordynamics and overall performance of the machine. Results will be compared to expected performance and how design changes were implanted to properly counter challenges during testing.


1984 ◽  
Vol 106 (2) ◽  
pp. 337-345
Author(s):  
B. Lakshminarayana ◽  
N. Sitaram

The annulus wall boundary layer inside the blade passage of the inlet guide vane (IGV) passage of a low-speed axial compressor stage was measured with a miniature five-hole probe. The three-dimensional velocity and pressure fields were measured at various axial and tangential locations. Limiting streamline angles and static pressures were also measured on the casing of the IGV passage. Strong secondary vorticity was developed. The data were analyzed and correlated with the existing velocity profile correlations. The end wall losses were also derived from these data.


2014 ◽  
Vol 543-547 ◽  
pp. 158-163 ◽  
Author(s):  
Zhen Zhen Duan ◽  
Yang Wei Liu ◽  
Li Peng Lu

The simulations of a low-speed axial compressor rotor with two tip clearance sizes, 0.5% chord and 1.5% chord, were performed in the study. Overall performance and detailed flow fields at near stall condition are analyzed. The results show that the rotor stall occurs at higher mass flow condition with large tip clearance. For the small tip clearance the tip leakage vortex and the corner vortex both contribute significantly to the rotor stall, and the interaction between the vortices promotes the stall generation. While for the large tip clearance the tip leakage vortex plays a primary role, and the vortices interaction is ignorable.


Author(s):  
Alan D. Henderson ◽  
Gregory J. Walker ◽  
Jeremy D. Hughes

The influence of free-stream turbulence on wake dispersion and boundary layer transition processes has been studied in a 1.5-stage axial compressor. An inlet grid was used to produce turbulence characteristics typical of an embedded stage in a multistage machine. The grid turbulence strongly enhanced the dispersion of inlet guide vane (IGV) wakes. This modified the interaction of IGV and rotor wakes, leading to a significant decrease in periodic unsteadiness experienced by the downstream stator. These observations have important implications for the prediction of clocking effects in multistage machines. Boundary layer transition characteristics on the outlet stator were studied with a surface hot-film array. Observations with grid turbulence were compared with those for the natural low turbulence inflow to the machine. The transition behavior under low turbulence inflow conditions with the stator blade element immersed in the dispersed IGV wakes closely resembled the behavior with elevated grid turbulence. It is concluded that with appropriate alignment, the blade element behavior in a 1.5-stage axial machine can reliably indicate the blade element behavior of an embedded row in a multistage machine.


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