Some Aspects of the Transonic Compressor Tandem Design

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Alexander Hergt ◽  
S. Grund ◽  
J. Klinner ◽  
W. Steinert ◽  
M. Beversdorff ◽  
...  
Keyword(s):  
Mach Number ◽  
Design Space ◽  
Wake Flow ◽  
Objective Functions ◽  
Flow Solver ◽  
Axial Compressors ◽  
Transonic Compressor ◽  
And Performance ◽  
Transonic Cascade ◽  
Operating Points

For the development of the latest generation of axial compressors, it is necessary to enlarge the design space by using advanced aerodynamic processes. This enables a further increase in efficiency and performance. The use of a tandem blade configuration in a transonic compressor row provides the possibility to enlarge the design space. It is necessary to address the design aspects a bit more in detail in order to efficiently apply this blading concept to turbomachinery. Therefore, in the current study, the known design aspects of tandem blading in compressors will be summed up under the consideration of the aerodynamic effects and construction characteristics of a transonic compressor tandem. Based on this knowledge, a new transonic compressor tandem cascade (DLR TTC) with an inflow Mach number of 0.9 is designed using modern numerical methods and a multi-objective optimization process. Three objective functions as well as three operating points are used in the optimization. Furthermore, both tandem blades and their arrangement are parameterized. From the resulting database of 1246 members, a final best member is chosen as the state-of-the-art design for further detailed investigation. The aim of the ensuing experimental and numerical investigation is to answer the question, whether the tandem cascade resulting from the modern design process fulfills the described design aspects and delivers the requested performance and efficiency criteria. The numerical simulations within the study are carried out with the DLR flow solver TRACE. The experiments are performed at the transonic cascade wind tunnel of DLR in Cologne. The inflow Mach number during the tests is 0.9, and the AVDR is adjusted to 1.3 (design value). Wake measurements with a three-hole probe are carried out in order to determine the cascade performance. The experimental results show an increase in losses and a reduction of the cascade deflection by about 2 deg compared to the design concept. Nevertheless, the experimental and numerical results allow a good understanding of the aerodynamic effects. In addition, planar PIV was applied in a single S1 plane located at midspan to capture the velocity field in the wake of blade 1 in order to analyze the wake flow in detail and describe its influence on the cascade deflection and loss behavior. Finally, an outlook will be given on what future tandem compressor research should be focused.

Some Aspects of Transonic Compressor Tandem Design

2018 ◽  
Author(s):  
A. Hergt ◽  
S. Grund ◽  
J. Klinner ◽  
W. Steinert ◽  
M. Beversdorff ◽  
...  
Keyword(s):  
Mach Number ◽  
Wake Flow ◽  
Objective Functions ◽  
Flow Solver ◽  
Axial Compressors ◽  
Transonic Compressor ◽  
Blade Row ◽  
High Level ◽  
Transonic Cascade ◽  
Operating Points

The development of modern axial compressors has already reached a high level. Therefore an enlargement of the design space by means of new or advanced aerodynamic methods is necessary in order to achieve further enhancements of performance and efficiency. The tandem arrangement of profiles in a transonic compressor blade row is such a method. It is necessary to address the design aspects a bit more in detail in order to efficiently apply this blading concept to turbomachinery. Therefore, in the current study the known design aspects of tandem blading in compressors will be summed up under consideration of the aerodynamic effects and construction characteristics of a transonic compressor tandem. Based on this knowledge, a new transonic compressor tandem cascade (DLRTTC) with an inflow Mach number of 0.9 is designed using modern numerical methods and a multi objective optimization process. Three objective functions as well as three operating points are used in the optimization. Furthermore, both tandem blades and their arrangement are parameterized. From the resulting database of 1246 members a final best member is chosen as state-of-the-art design for further detailed investigation. The aim of the ensuing experimental and numerical investigation is to answer the question, whether the tandem cascade resulting from the modern design process fulfills the described design aspects and delivers the requested performance and efficiency criteria. The numerical simulations within the study are carried out with the DLR flow solver TRACE. The experiments are performed at the Transonic Cascade Wind Tunnel of DLR in Cologne. The inflow Mach number during the tests is 0.9 and the AVDR [1, 2] is adjusted to 1.3 (design value). Wake measurements with a 3-hole probe are carried out in order to determine the cascade performance. The experimental results show an increase in losses and a reduction of the cascade deflection by about 2 degrees compared to design concept. Nevertheless, the experimental and numerical results allow a good understanding of the aerodynamic effects. In addition, Planar PIV was applied in a single S1 plane located at midspan to capture the velocity field in the wake of blade 1 in order to analyze the wake flow in detail and describe its influence on the cascade deflection and loss behavior. Finally, an outlook will be given on what future tandem compressor research should be focused.

Design of Industrial Axial Compressor Blade Sections for Optimal Range and Performance

2003 ◽  
Author(s):  
Frank Sieverding ◽  
Beat Ribi ◽  
Michael Casey ◽  
Michael Meyer
Keyword(s):  
Genetic Algorithm ◽  
Fitness Function ◽  
Optimization Technique ◽  
Axial Compressor ◽  
Design System ◽  
Flow Solver ◽  
Axial Compressors ◽  
Mechanical Constraints ◽  
And Performance ◽  
Operating Points

A design system for the blade sections of industrial axial compressors has been developed. The method combines a parametric geometry definition method, a powerful blade-to-blade flow solver (MISES) and an optimization technique (breeder genetic algorithm) with an appropriate fitness function. Particular effort has been devoted to the design of the fitness function for this application which includes non-dimensional terms related to the required performance at design and off-design operating points. It has been found that essential aspects of the design (such as the required flow turning, or mechanical constraints) should not be part of the fitness function, but need to be treated as so-called “killer” criteria in the genetic algorithm. Finally, it has been found worthwhile to examine the effect of the weighting factors of the fitness function to identify how these affect the performance of the sections. The system has been tested on the design of a repeating stage for the middle stages of an industrial axial compressor. The resulting profiles show an increased operating range compared to an earlier design using NACA65 profiles.

Design Method for Subsonic and Transonic Cascade With Prescribed Mach Number Distribution

1992 ◽  
Vol 114 (3) ◽  
pp. 553-560 ◽  
Author(s):  
O. Le´onard ◽  
R. A. Van den Braembussche
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Velocity Component ◽  
Design Method ◽  
Normal Velocity ◽  
Flow Solver ◽  
Number Distribution ◽  
Mach Number Distribution ◽  
Transonic Cascade

A iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a nonzero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade.

About Transonic Compressor Tandem Design: A Principle Study

2015 ◽  
Author(s):  
A. Hergt ◽  
U. Siller
Keyword(s):  
Industrial Application ◽  
Design Space ◽  
Research Work ◽  
Design Principles ◽  
Compressor Blade ◽  
Tandem Arrangement ◽  
Axial Compressors ◽  
Transonic Compressor ◽  
Blade Row ◽  
High Level

The development of modern axial compressors has already reached a high level. Therefore an enlargement of the design space by means of new or advanced aerodynamic methods is necessary in order to achieve further enhancements of performance and efficiency. The tandem arrangement of profiles in a transonic compressor blade row is such a method. For an efficient industrial application the knowledge of the fundamental design principles is needed. This paper presents the recent research work on transonic compressor tandem profiles at DLR Institute of Propulsion Technology. It deals with the fundamental description of the operation principles of a modern transonic compressor tandem cascade. By considering these principles and based on an optimization database with over 1200 members design recommendations are developed.

Axis-Asymmetric Profiled Endwall Design by Using Multiobjective Optimisation Linked With 3D RANS-Flow-Simulations

2007 ◽  
Author(s):  
Christian Dorfner ◽  
Eberhard Nicke ◽  
Christian Voss
Keyword(s):  
The Novel ◽  
3D Flow ◽  
Flow Solver ◽  
Axial Compressors ◽  
Flow Simulations ◽  
Flow Loss ◽  
Engine Components ◽  
Operating Points ◽  
Isentropic Efficiency ◽  
Wide Operating

Secondary flow loss in modern axial compressors is considered to be the prime reason for the reduction of overall isentropic efficiency in these engine components. This paper presents a new methodology to diminish blade secondary loss and endwall loss by an axis-asymmetric modification of endwalls using an automated multiobjective optimizer in conjunction with 3D-RANS-flow-simulations. In order to obtain a favorable design for a wide operating range, the most important operating-points are considered in the optimization process. The existing multiobjective optimization package is enhanced by implementation of DLR’s in-house 3D-flow-solver TRACE. A straightforward stator optimization was performed for a 3D-process-chain test run. Finally, the novel endwall design technique is introduced and the first optimization results and further studies are discussed.

scholarly journals Numerical and Experimental Investigation of the Wake Flow Downstream of a Linear Turbine Cascade

1998 ◽  
Author(s):  
Wolfgang Sanz ◽  
Arno Gehrer ◽  
Jakob Woisetschläger ◽  
Martin Forstner ◽  
Wolfgang Artner ◽  
...  
Keyword(s):  
Turbulence Modeling ◽  
Turbulence Models ◽  
Wake Flow ◽  
Navier Stokes ◽  
Laser Doppler Velocimeter ◽  
Turbine Cascade ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
And Performance ◽  
Transonic Cascade

In turbomachinery the wake flow together with the inherent unsteadiness caused by interaction between stator and rotor has a significant impact on efficiency and performance. The prediction of the wake flow depends largely on the turbulence modeling. Therefore in this study the evolution of a viscous wake downstream of a linear turbine cascade is experimentally and computationally investigated. In a transonic cascade test stand Laser Doppler Velocimeter (LDV) measurements of velocity and turbulent kinetic energy are done in several axial planes downstream of the blade trailing edge. Two different turbulence models are then incorporated into a two-dimensional Navier-Stokes solver to calculate the turbulent wake flow and the results are compared with the experimental data to test the quality of the turbulence models. The large discrepancies between measurement and Calculation are assumed to be caused by the periodic vortex shedding from the blunt trailing edge which is not taken into account by the turbulence models. But further research is needed to resolve this issue.

A Comparative Study of Two Preconditioners for Solving 3D Inviscid Low Speed Flows

2011 ◽  
Vol 110-116 ◽  
pp. 423-430 ◽  
Author(s):  
Kazem Hejranfar ◽  
Ramin Kamali Moghadam
Keyword(s):  
Mach Number ◽  
Comparative Study ◽  
Euler Equations ◽  
Finite Volume ◽  
Eigenvalues And Eigenvectors ◽  
Flow Solver ◽  
Low Mach Number ◽  
Euler Flow ◽  
A Cell ◽  
And Performance

In the present study, two preconditioners proposed by Eriksson, and Choi and Merkel are implemented on a 3D upwind Euler flow solver on unstructured meshes. The mathematical formulations of these preconditioning schemes for the set of primitive variables are drawn and their eigenvalues and eigenvectors are compared with each others. A cell-centered finite volume Roe's method is used for discretization of the 3D preconditioned Euler equations. The accuracy and performance of these preconditioning schemes are examined by computing low Mach number flows over the ONERA M6 wing for different conditions.

On the Mechanism of Spike Stall Inception and Near Stall Non-Synchronous Vibration in an Axial Compressor

2020 ◽  
Author(s):  
Daniel Möller ◽  
Heinz-Peter Schiffer
Keyword(s):  
Shear Layer ◽  
Flow Analysis ◽  
Axial Compressor ◽  
Experimental Investigations ◽  
Flow Solver ◽  
Stall Inception ◽  
Transonic Compressor ◽  
Transient Data ◽  
Stable Characteristic ◽  
Operating Points

Abstract The aerodynamic and aeroelastic behavior of an engine-like transonic compressor stage is investigated in this paper. Simulations were carried out for the transonic compressor at the Technical University of Darmstadt using the AU3D flow solver. A comparison with previous experimental investigations shows close agreement for both steady and transient data. The simulations enable a detailed flow analysis during spike stall inception and non-synchronous vibrations (NSV) at operating points close to the stall limit. The aerodynamic structure of shear layer fluctuations in the rotor tip region during the initial phase of spike stall inception is investigated. Already before the stall limit is reached such fluctuations can occur. In this case, the compressor continues to operate on the aerodynamically stable characteristic and NSV might be excited due to the unsteady blade force. This paper concludes with a joint analytical interpretation of the shear layer fluctuations observed at the beginning of spike stall and during near stall NSV by basic flow principles.

scholarly journals Design, Optimization, and Analysis of a High-Turning Transonic Tandem Compressor Cascade

1997 ◽  
Author(s):  
Anton Weber ◽  
Wolfgang Steinert
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Side Wall ◽  
Design Flow ◽  
Basic Question ◽  
Compressor Cascade ◽  
Flow Angle ◽  
Transonic Compressor ◽  
Blade Row ◽  
Transonic Cascade

As a feasibility study for a stator guide vane a highly loaded transonic compressor stator blade row was designed, optimized, and tested in a transonic cascade facility. The flow entering the turning device with an inlet Mach number of 1.06 has to be turned by more than 60° and diffused extremely to leave the blade row without swirl. Therefore, the basic question was: Is it feasible to gain such a high amount of flow turning with an acceptable level of total pressure losses? The geometric concept chosen is a tandem cascade consisting of a transonic blade row with a flow turning of 10° followed by a subsequent high-turning subsonic cascade. The blade number ratio of the two blade rows was selected to be 1:2 (transonic: subsonic). Design and optimization have been performed using a modern Navier-Stokes flow solver under 2D assumptions by neglecting side wall boundary-layer effects. In the design process it was found to be necessary to guide the wake of the low turning transonic blade near the suction surface of the subsonic blade. Furthermore, it is advantageous to enlarge the blade spacing of the ‘wake’ passage in relation to the neighbouring one of the high turning part. The optimized design geometry of the tandem cascade was tested in the transonic cascade windtunnel of the DLR in Cologne. At design flow conditions the experiments confirmed the design target in every aspect. A flow turning of more than 60°, a static pressure ratio of 1.75, and a total pressure loss coefficient of 0.15 was measured. The working range at design inlet Mach number of 1.06 is about 3.5° in terms of the inlet flow angle. A viscous analysis of various operating points showed excellent agreement with the experimental results.

Non-Axisymmetric End Wall Profiling in Transonic Compressors—Part I: Improving the Static Pressure Recovery at Off-Design Conditions by Sequential Hub and Shroud End Wall Profiling

2009 ◽  
Author(s):  
Steffen Reising ◽  
Heinz-Peter Schiffer
Keyword(s):  
Numerical Study ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Cross Flow ◽  
Axial Compressor ◽  
Secondary Flows ◽  
Flow Solver ◽  
Axial Compressors ◽  
Transonic Compressor ◽  
End Wall

Secondary flows involving cross flow and three-dimensional separation phenomena in modern axial compressors at high stage loading contribute significantly to a reduction in overall efficiency. This two-part paper presents a numerical study on the potential aerodynamic benefits of using non-axisymmetric end walls in an axial compressor, involving both the rotor and the stator row. This first paper describes the sequential profiling of stator end walls in a transonic compressor at several operating points to suppress separation. An automated multi-objective optimizer connected to a 3-D RANS flow solver was used to find the optimal end wall geometries. As a design exercise, the stator hub end wall of Configuration I of the Darmstadt Transonic Compressor was first optimized at design conditions, keeping the shroud end wall constant. This led to an increase in efficiency of 1.8% due to the suppression of the hub-corner stall. However, this was accompanied by an increased area of reverse flow at the casing, which was even more distinct at off-design conditions near stall. The numerical surge limit of the datum axisymmetric design could no longer be reached and was then determined by the new separation close to the stator casing. A subsequent optimization of the shroud end wall was carried out using the improved profiled hub as the initial design. An operating point near stall with a strongly developed separation was chosen for this purpose. The second optimization resulted in a further improvement in the characteristic speed line over the entire off-design region. Although the shroud contour was designed at off-design conditions, the optimization gained an additional 0.03% in efficiency for the design point. The lower surge limit of the datum design could also be reached again, even at higher efficiency and pressure ratios. The investigations showed that end wall profiling in high loaded compressor stators can be considered as a good supplement to 3-D blading to control separation areas and improve the entire component’s characteristics.

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