• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.85-91
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• 2012

Numerical simulations on a single stage transonic compressor which is developed by Korea Aerospace Research Institute are carried out and their results are compared with experimental data for cross validations. Comparisons between experimental data and numerical simulation results show good agreements on a performance curve, static pressure and total pressure distributions. CFD results show that there is a clear interaction between tip leakage flow and normal shock in the rotor passage. Tip leakage flows are almost dissipated after the strong normal shock and it forms a strong recirculation near the blade tip. Also a large separation region grows on the suction surface just after the normal shock. As the pressure ratio and blade loading increase, the normal shock line moves upstream and it starts to deviate from the blade leading edge. Then the tip leakage flow does not overcome the strong adverse pressure gradient and flow blockage originated from the tip recirculation region. As a result, the tip leakage flow heads for the neighboring blade leading edge, which results in a compressor stall.

• The KSFM Journal of Fluid Machinery
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• v.10 no.2 s.41
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• pp.22-31
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• 2007

This paper describes the shape optimization of rotor blade in a transonic axial compressor rotor. Three surrogate models, Kriging, radial basis neural network and response surface methods, are introduced to find optimum blade shape and to compare the characteristics of object function at each optimal design condition. Blade sweep, lean and skew are considered as design variables and adiabatic efficiency is selected as an objective function. Throughout the shape optimization of the compressor rotor, the predicted adiabatic efficiency has almost same value for three surrogate models. Among the three design variables, a blade sweep is the most sensitive on the object function. It is noted that the blade swept to backward and skewed to the blade pressure side is more effective to increase the adiabatic efficiency in the axial compressor Flow characteristics of an optimum blade are also compared with the results of reference blade.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.179-186
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• 1999

Three-dimensional flow analysis is implemented to investigate the flow through transonic axial-flow compressor rotor(NASA R67), and to evaluate the performances of k-$\epsilon$ and Baldwin-Lomax turbulence models. A finite volume method is used for spatial discretization. And, the equations are solved implicitly in time with the use of approximate factorization. Upwind difference scheme is used for inviscid terms, but viscous terms are centrally differenced. The flux-difference-splitting of Roe is used to obtain fluxes at the cell faces. Numerical analysis is performed near peak efficiency and near stall. And, the results are compared with the experimental data for NASA R67 rotor. Blade-to-Blade Mach number distributions are compared to confirm the accuracy of the code. From the results, we conclude that k-$\epsilon$ model is better for the calculation of flow rate and efficiency than Baldwin-Lomax model. But, the predictions for Mach number and shock structure are almost same.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.20-28
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• 2010

This paper deals with the Design and Analysis of a Controlled Diffusion Aerofoil (CDA) Blade Section for an Axial Compressor Stator and Effect of incidence angle and Mach No. on Performance of CDA. CD blade section has been designed at Axial Flow Compressor Research Lab, Propulsion Division of National Aerospace Laboratories (NAL), Bangalore, as per geometric procedure specified in the U.S. patent (4). The CFD analysis has been performed by a 2-D Euler code (Denton's code), which gives surface Mach No. distribution on the profiles. Boundary layer computations were performed by a 2-D boundary layer code (NALSOF0801) available in the SOFFTS library of NAL. The effect of variation of Mach no. was performed using fluent. The surface Mach no. distribution on the CD profile clearly indicates lower peak Mach no. than MCA profile. Further, boundary layer parameters on CD aerofoil at respective incidences have lower values than corresponding MCA blade profile. Total pressure loss on CD aerofoil for the same incidence range is lower than MCA blade profile.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.209-214
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• 2002

The present study is to compare the performance of turbulence models in the analysis of the complex flowfield of an axial flow compressor. Baldwin-Lomax turbulence model and k-$\omega$ turbulence model were selected for the comparison. The thin-layer Wavier-Stokes equation was calculated by explicit, finite-difference numerical scheme. A spatially-varying time-step and an implicit residual smoothing were used to improve convergence. Experimental measurements for NASA rotor 37 were cited fer the comparison with numerical data. The compared two turbulence models gave similar performance over all except for total pressure.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.9-16
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• 2007

Deterioration of surface of turbomachinery blades occurs in course of time due to many factors and hence reduces the performance of the machine. In this paper, the effects of surface roughness of transonic axial compressor blade on performance are studied considering a reference blade and a shape distorted (optimized) blade. Optimal blade is designed considering sweep and lean. Baldwin-Lomax turbulence model is used for flow field analysis and Cebeci-Smith roughness model is formulated for roughness modeling. It is found that, as the surface roughness increases, adiabatic efficiency, total temperature ratio and total pressure ratio decrease while Mach number increases. Performance deterioration is more severe in case of distorted blade as compared to reference blade.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.543-544
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• 2006

Shape optimization of a transonic axial compressor rotor operating at the design flow condition has been performed using three-dimensional Navier-Stokes analysis and three different surrogate models: i.e.., Response Surface Method(RSM), Kriging Method, and Radial Basis Function(RBF). Three design variables of blade sweep, lean and skew are introduced to optimize the three-dimensional stacking line of the rotor blade. The object function of the shape optimization is selected as an adiabatic efficiency. Throughout the shape optimization of the rotor blade, the adiabatic efficiency is increased for the three different surrogate models. Detailed flow characteristics at the optimal blade shape obtained by different optimization method are drawn and discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1384-1391
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• 2001

Three-dimensional flow analysis is implemented to investigate the flow through transonic axial-flow compressor rotor(NASA R67) and to evaluate the performances of Abid's low-Reynolds-number k-$\omega$ and Baldwin-Lomax turbulence models. A finite volume method is used fur spatial discretization. The equations are solved implicitly in time by the use of approximate factorization. The upwind difference scheme is used for inviscid terms and viscous terms are approximated with central difference. The flux-difference-splitting method of Roe is used to obtain fluxes at the cell faces. Numerical analysis is performed near peak efficiency and near stall. The results are compared with the experimental data for NASA R67 rotor. Blade-to-Blade Mach number distributions are compared to confirm the accuracy of the code. From the results, it is concluded that Abid'k-$\omega$ model is better for the calculation of flow rate and efficiency than Baldwin-Lomax model. But, the predictions for Mach number and shock structure are almost the same.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.155-162
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• 2003

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. It is also found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.135-142
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• 2001

Design optimization of a transonic compressor rotor (NASA rotor 37) using response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. Ana, it is found that the design process provides reliable design of a turbomachinery blade with reasonable computing time.