Advanced Nonaxisymmetric Endwall Contouring for Axial Compressors by Generating an Aerodynamic Separator—Part II: Experimental and Numerical Cascade Investigation

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Alexander Hergt ◽  
Christian Dorfner ◽  
Wolfgang Steinert ◽  
Eberhard Nicke ◽  
Heinz-Adolf Schreiber
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Suction Side ◽  
Significant Loss ◽  
Optimization Techniques ◽  
Navier Stokes ◽  
Loss Reduction ◽  
Axial Compressors ◽  
Flow Phenomena

Modern methods for axial compressor design are capable of shaping the blade surfaces in a three-dimensional way. Linking these methods with automated optimization techniques provides a major benefit to the design process. The application of nonaxisymmetric contoured endwalls is considered to be very successful in turbine rotors and vanes. Concerning axial compressors, nonaxisymmetric endwalls are still a field of research. This two-part paper presents the recent development of a novel endwall design. A vortex created by a nonaxisymmetric endwall groove acts as an aerodynamic separator, preventing the passage vortex from interacting with the suction side boundary layer. This major impact on the secondary flow results in a significant loss reduction by means of load redistribution, reduction in recirculation areas, and suppressed corner separation. Part I of this paper deals with the endwall design and its compressor application. The resulting flow phenomena and physics are described and analyzed in detail. The second paper presents the detailed experimental and numerical investigation of the developed endwall groove. The measurements carried out at the transonic cascade wind tunnel of DLR in Cologne, demonstrated a considerable influence on the cascade performance. A loss reduction and redistribution of the cascade loading were achieved at the aerodynamic design point, as well as near the stall condition of the cascade. This behavior is well predicted by the numerical simulation. The combined analysis of experimental and numerical flow patterns allows a detailed interpretation and description of the resulting flow phenomena. In this context, high fidelity 3D-Reynolds-averaged Navier–Stokes flow simulations are required to analyze the complex blade and endwall boundary layer interaction.

Advanced Non-Axisymmetric Endwall Contouring for Axial Compressors by Generating an Aerodynamic Separator—Part II: Experimental and Numerical Cascade Investigation

2009 ◽  
Author(s):  
Alexander Hergt ◽  
Christian Dorfner ◽  
Wolfgang Steinert ◽  
Eberhard Nicke ◽  
Heinz-Adolf Schreiber
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Suction Side ◽  
Significant Loss ◽  
Optimization Techniques ◽  
Loss Reduction ◽  
Axial Compressors ◽  
Boundary Layer Interaction ◽  
Flow Phenomena

Modern methods for axial compressor design are capable of shaping the blade surfaces in a three dimensional way. Linking these methods with automated optimization techniques provides a major benefit to the design process. The application of non-axisymmetric contoured endwalls is considered to be very successful in turbine rotors and vanes. Concerning axial compressors non-axisymmetric endwalls are still a field of research. This two-part paper presents the recent development of a novel endwall design. A vortex created by a nonaxisymmetric endwall groove acts as an aerodynamic separator, preventing the passage vortex from interacting with the suction side boundary layer. This major impact on the secondary flow results in a significant loss reduction by means of load redistribution, reduction of recirculation areas and suppressed corner separation. Part I of this paper deals with the endwall design and its compressor application. The resulting flow phenomena and physics are described and analysed in detail. The second paper presents the detailed experimental and numerical investigation of the developed endwall groove. The measurements carried out at the transonic cascade wind tunnel of DLR in Cologne, demonstrated a considerable influence on the cascade performance. A loss reduction and redistribution of the cascade loading were achieved at the aerodynamic design point as well as near the stall condition of the cascade. This behaviour is well predicted by the numerical simulation. The combined analysis of experimental and numerical flow patterns allows a detailed interpretation and description of the resulting flow phenomena. In this context high fidelity 3D-RANS flow simulations are required to analyse the complex blade and endwall boundary layer interaction.

Advanced Non-Axisymmetric Endwall Contouring for Axial Compressors by Generating an Aerodynamic Separator—Part I: Principal Cascade Design and Compressor Application

2009 ◽  
Author(s):  
Christian Dorfner ◽  
Alexander Hergt ◽  
Eberhard Nicke ◽  
Reinhard Moenig
Keyword(s):  
Three Dimensional ◽  
Axial Compressor ◽  
Significant Loss ◽  
Optimization Techniques ◽  
Tip Vortex ◽  
Compressor Cascade ◽  
Axial Compressors ◽  
Flow Phenomena ◽  
Endwall Contouring ◽  
Automated Optimization

Modern methods for axial compressor design are capable of shaping the blade surfaces in a three dimensional way. Linking these methods with automated optimization techniques provides a major benefit to the design process. The application of non-axisymmetric contoured endwalls is considered to be very successful in turbine rotors and vanes. Concerning axial compressors non-axisymmetric endwalls are still a field of research. This two-part paper presents the recent development of a novel endwall design. An aerodynamic separator, generated by a non-axisymmetric endwall groove, interacts with the passage vortex. This major impact on the secondary flow results in a significant loss reduction because of load redistribution, reduction of recirculation areas and suppressed corner separation. The first paper deals with the development of the initial endwall design using a linear compressor cascade application. A brief introduction of the design methods is provided, including the automated optimization, the 3D process chain with a focus on the endwall contouring tool. Hereafter the resulting flow phenomena and physics due to the modified endwall surface are described and analyzed in detail. Additionally, the endwall design principal is transferred to an axial compressor stage. The endwall groove is applied to the hub and casing endwalls of the stator and the initial numerical investigation is presented. For highly loaded operating points the flow behaviour at the hub region can be improved in accord with the cascade results. Obviously, the casing region is dominated by the incoming tip vortex generated by the rotor and still remains an area for further investigations concerning non-axisymmetric endwall contouring.

Advanced Nonaxisymmetric Endwall Contouring for Axial Compressors by Generating an Aerodynamic Separator—Part I: Principal Cascade Design and Compressor Application

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Christian Dorfner ◽  
Alexander Hergt ◽  
Eberhard Nicke ◽  
Reinhard Moenig
Keyword(s):  
Flow Behavior ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Significant Loss ◽  
Optimization Techniques ◽  
Tip Vortex ◽  
Compressor Cascade ◽  
Axial Compressors ◽  
Endwall Contouring ◽  
Automated Optimization

Modern methods for axial compressor design are capable of shaping the blade surfaces in a three-dimensional way. Linking these methods with automated optimization techniques provides a major benefit to the design process. The application of nonaxisymmetric contoured endwalls is considered to be very successful in turbine rotors and vanes. Concerning axial compressors, nonaxisymmetric endwalls are still a field of research. This two-part paper presents the recent development of a novel endwall design. An aerodynamic separator, generated by a nonaxisymmetric endwall groove, interacts with the passage vortex. This major impact on the secondary flow results in a significant loss reduction because of load redistribution, reduction in recirculation areas, and suppressed corner separation. The first paper deals with the development of the initial endwall design using a linear compressor cascade application. A brief introduction of the design methods is provided, including the automated optimization and the 3D process chain with a focus on the endwall contouring tool. Hereafter, the resulting flow phenomena and physics due to the modified endwall surface are described and analyzed in detail. Additionally, the endwall design principal is transferred to an axial compressor stage. The endwall groove is applied to the hub and casing endwalls of the stator, and the initial numerical investigation is presented. For highly loaded operating points, the flow behavior at the hub region can be improved in accord with the cascade results. Obviously, the casing region is dominated by the incoming tip vortex generated by the rotor and still remains an area for further investigations concerning nonaxisymmetric endwall contouring.

Study of Three-Dimensional Viscous Flows in an Axial Compressor Cascade Including Tip Leakage Effects Using a SIMPLE-Based Algorithm

1986 ◽  
Vol 108 (1) ◽  
pp. 51-58 ◽  
Author(s):  
M. Pouagare ◽  
R. A. Delaney
Keyword(s):  
Numerical Simulation ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Simple Algorithm ◽  
Suction Side ◽  
Tip Clearance ◽  
High Loading ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Flow Phenomena

A multisweep space-marching solver based on a modified version of the SIMPLE algorithm was employed to study the three-dimensional flow field through a linear cascade. Three cases were tested: one with moderate loading, one with high loading, and one with high loading and tip clearance. The results of the numerical simulation were compared with available experimental measurements, and the agreement between the two was found satisfactory. The numerical simulation provided insight into several important endwall flow phenomena such as the interaction between the leakage and passage vortices, the interaction between the leakage vortex and the wake, the effect of leakage flow and loading on losses and secondary kinetic energy, the suction side corner separation, and the blowing of this separation by the leakage flow.

Modelling of spanwise mixing in compressor through-flow computations

1997 ◽  
Vol 211 (3) ◽  
pp. 243-251 ◽  
Author(s):  
J Dunham
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Streamline Curvature ◽  
Wall Boundary Layer ◽  
Through Flow ◽  
Compressor Design ◽  
Multistage Compressors ◽  
End Wall

Although three-dimensional Navier-Stokes computations are coming into use more and more, streamline curvature through-flow computations are still needed, especially for multistage compressors, and where codes which run in minutes rather than hours are preferred. These methods have been made more realistic by taking account of end-wall effects and spanwise mixing by four aerodynamic mechanisms: turbulent diffusion, turbulent convection by secondary flow, spanwise migration of aerofoil boundary layer fluid and spanwise convection of fluid in blade wakes. This paper describes the models adopted in the DRA streamline curvature method for axial compressor design and analysis. Previous papers are summarized briefly before describing the new part of the model—that accounting for aerofoil boundary layers and wakes. Other changes to the previously published annulus wall boundary layer model have been made to enable it to cater for separations and end bends. The resulting code is evaluated against a range of experimental and computational results.

Design Optimization of Axial Flow Compressor Blades With Three-Dimensional Navier-Stokes Solver

2000 ◽  
Author(s):  
Sang-Yun Lee ◽  
Kwang-Yong Kim
Keyword(s):  
Numerical Optimization ◽  
Golden Section ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Axial Flow ◽  
Optimization Techniques ◽  
Search Direction ◽  
Navier Stokes ◽  
Optimum Shape ◽  
Optimization Search

Numerical optimization techniques combined with a three-dimensional thin-layer Navier-Stokes solver are presented. The techniques are used to find an optimum shape of a stator blade in an axial compressor through calculations of single stage rotor-stator flow. The Baldwin-Lomax model is chosen to describe turbulence. For the numerical optimization, search direction is calculated using the steepest decent method and the conjugate direction method. The golden section method is used to determine optimum moving distance along the search direction. The object of the present optimization is to maximize the efficiency. An optimum stacking line is found which produces a custom-tailored three-dimensional blade design.

scholarly journals Physics of Airfoil Clocking in a High-Speed Axial Compressor

1998 ◽  
Author(s):  
Daniel J. Dorney ◽  
Om P. Sharma ◽  
Karen L. Gundy-Burlet
Keyword(s):  
Relative Motion ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Unsteady Aerodynamics ◽  
Navier Stokes ◽  
Jet Engines ◽  
Axial Compressors ◽  
Multi Stage ◽  
Significant Performance

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and stator airfoils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead to progressively more complex wake/wake and wake/airfoil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. In addition, as the Mach number increases the interaction between blade rows can be intensified due to potential effects. In the current study an unsteady, quasi-three-dimensional Navier-Stokes analysis has been used to investigate the unsteady aerodynamics of stator clocking in a 1-1/2 stage compressor, typical of back stages used in high-pressure compressors of advanced commercial jet engines. The effects of turbulence have been modeled with both algebraic and two-equation models. The results presented include steady and unsteady surface pressures, efficiencies, boundary layer quantities and turbulence quantities. The main contribution of the current work has been to show that airfoil clocking can produce significant performance variations at the Mach numbers associated with an engine operating environment. In addition, the growth of turbulence has been quantified to aid in the development of models for the multi-stage steady analyses used in design systems.

A New Approach for Compressor Endwall Contouring

2011 ◽  
Author(s):  
Alexander Hergt ◽  
Robert Meyer ◽  
Karsten Liesner ◽  
Eberhard Nicke
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Performance Enhancement ◽  
Cross Flow ◽  
Suction Side ◽  
Significant Loss ◽  
Compressor Cascade ◽  
Boundary Layer Interaction ◽  
Flow Phenomena ◽  
Flow Effects

Against the background of the high development status of modern axial compressors, a further performance enhancement is linked with the extension of the design space in the development process and the concentration on the essential loss mechanisms in the compressor. The performance of a compressor cascade is considerably influenced by secondary flow effects in the near endwall region, since up to 50 percent (for low aspect ratio) of the losses in the bladed channel of a turbomachinery are linked to the endwalls. In this context the application of non-axisymmetric profiled endwalls provides a potential for compressor improvement. The paper presents the detailed experimental and numerical investigation of controlling the endwall cross flow in a compressor cascade. The general approach is based on a boundary layer fence arrangement, whose application on the compressor endwall works as a non-axisymmetric endwall contour. This non-axisymmetric endwall modification constrains the interaction of the endwall cross flow with the suction side boundary layer, thus the onset of the corner separation is delayed and a significant loss reduction of 8 percent is achieved. The experiments were carried out in a linear compressor cascade at the high-speed cascade wind tunnel of the DLR in Berlin at peak efficiency (design point) and off-design of the cascade at Mach number M = 0.67. Furthermore, high fidelity 3D-RANS flow simulations were performed in order to analyze the complex blade and endwall boundary layer interaction. The combined consideration of experimental and numerical flow pattern allows a detailed interpretation and description of the resulting flow phenomena.

The Design, Development and Evaluation of 3D Aerofoils for High Speed Axial Compressors: Part 2 — Simulation and Comparison With Experiment

2005 ◽  
Author(s):  
G. Woollatt ◽  
D. Lippett ◽  
P. C. Ivey ◽  
P. Timmis ◽  
B. A. Charnley
Keyword(s):  
Collaborative Design ◽  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Loss Reduction ◽  
Test Results ◽  
Design Development ◽  
Axial Compressors ◽  
Quantitative Basis ◽  
End Wall

The focus of this paper is to report on measurements from and simulation of Cranfield University’s 3-stage high-speed axial compressor test rig. This newly built rig is supported by European Commission funding and has tested a set of conventionally stacked 2D rotor and stator blades (Reference 1). The results were used to evaluate and to assess the performance of several commercially available CFD codes leading to the collaborative design of an advanced three-dimensional blade set. The philosophy behind the advanced design is described. The datum test results show that the state of the art, highly loaded, datum compressor is well matched with limited potential for loss reduction. A comparison is made between the measured results and a series of numerical analyses using the various CFD codes. Although the codes showed reasonable qualitative agreement with each other and the measured data, there were significant differences in the predicted performance of the datum build. Further the codes were unable to grade candidate redesigns consistently on a quantitative basis and therefore increased the difficulty of selecting suitable ‘3d’ features. Generic studies involving sweep, lean and recambering are used to evolve a design philosophy for the advanced three-dimensional design. Over cambering of the end-wall sections, coupled with a suitable stack of the blades, enables the blade count to be reduced. In the presence of a clearance combinations of sweep and lean are used to modify the loading in the clearance gap, thereby influencing the associated losses. The application of three-dimensional features redistributes the flow. The opportunity is therefore taken to rematch the sections based on the predicted results of the CFD codes. The above philosophy is used in the redesign of the datum compressor. Overall characteristics and exit traverse results from the test of the advanced build are compared to those from the datum build.

scholarly journals Body-force and mean-line models for the generation of axial compressor sub-idle characteristics

2020 ◽  
Vol 124 (1281) ◽  
pp. 1683-1701 ◽  
Author(s):  
M. Righi ◽  
L.E. Ferrer-Vidal ◽  
V. Pachidis
Keyword(s):  
Body Force ◽  
Computational Cost ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Axial Compressors ◽  
Characteristic Lines ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points ◽  
Low Order

ABSTRACTThis paper describes the application of low-order models to the prediction of the steady performance of axial compressors at sub-idle conditions. An Euler body-force method employing sub-idle performance correlations is developed and presented alongside a mean-line approach employing the same set of correlations. The low-order tools are used to generate the characteristic lines of the compressor in the locked-rotor and zero-torque windmilling conditions. The results are compared against steady-state operating points from three-dimensional (3D) Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations. The accuracy of the low-order tools in reproducing the results from high-fidelity CFD is analysed, and the trade-off with the computational cost of each method is discussed. The low-order tools presented are shown to offer a fast alternative to traditional CFD which can be used to predict the performance in sub-idle conditions of a new compressor design during early development stages.

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