scholarly journals Assessment of a Three-Dimensional Potential Code for Axial and Radial Blade Row Flows

1986 ◽  
Author(s):  
H.-H. Frühauf ◽  
D. Krämer ◽  
U. Küster
Keyword(s):  
Three Dimensional ◽  
Cross Flow ◽  
Vortex Sheet ◽  
Full Potential ◽  
Aerodynamic Design ◽  
Blade Row ◽  
Circulation Distribution ◽  
Flow Effects ◽  
Downstream Flow ◽  
New Formulation

An assessment of a three-dimensional potential code is presented for axial and radial blade row flows, for which experimental data or computational results are available. The prediction of a flow case with severe cross flow is included. Numerous 3-D potential flow effects will be discussed. The conservative full potential equation for 3-D transonic flow is solved by a robust SLOR method. A new formulation of the downstream flow ensures the computability of blade row flows with arbitrary spanwise circulation distributions. Blade circulation distribution and downstream flow properties are obtained as a part of the solution. The surface representation in parameter form in the geometry definition program and the mesh generation program, as well as the tensor notation of the basic equation and a configuration-independent vortex sheet approximation prediction, ensure the computability of flows through blade rows with arbitrary complex geometries. The CRAY-1/M incore version of the code is inexpensive enough to be used in the aerodynamic design process of new blade rows with irrotational inflows.

Three-dimensional instabilities in steady and unsteady non-parallel boundary layers, including effects of Tollmien-Schlichting disturbances and cross flow

1987 ◽  
Vol 409 (1837) ◽  
pp. 229-248 ◽  
Keyword(s):  
Boundary Layers ◽  
Large Scale ◽  
Three Dimensional ◽  
Steady Motion ◽  
Cross Flow ◽  
Parallel Flows ◽  
Roughness Elements ◽  
Tollmien Schlichting ◽  
Flow Effects ◽  
Secondary Instabilities

Three-dimensional (3D) linear stability properties are considered for steady and unsteady 2D or 3D boundary layers with significant non-parallelism present. Two main examples of such non-parallel flows whose stability is of interest are, firstly, steady motion, over roughness elements, in cross flow, or in large-scale separation and, secondly, unsteady 2D Tollmien-Schlichting (TS) motion, with its associated question of secondary instabilities. A high-frequency stability analysis is presented here. It is found that, for 2DTS or steady boundary layers, there is a swing in the direction of maximum TS spatial growth rate, from 0° for parallel flow towards 64.68° away from the free-stream direction, as the nonparallel flow effects increase. These effects then depend principally on, and indeed are proportional to, the local slope of the boundary-layer displacement. Cross flow can also have a profound impact on TS instabilities. Further implications for higher-amplitude and/or fasterscale disturbances, their secondary instability, and nonlinear interactions, are also discussed.

A Geometry Generation Framework for Contoured Endwalls

2019 ◽  
Author(s):  
L. E. Wood ◽  
R. R. Jones ◽  
O. J. Pountney ◽  
J. A. Scobie ◽  
D. A. S. Rees ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Construction Methods ◽  
Novel Approach ◽  
Wide Range ◽  
Blade Row ◽  
Flow Features ◽  
Flow Effects ◽  
Geometric Variation

Abstract The mainstream, or primary, flow in a gas turbine annulus is characteristically two-dimensional over the mid-span region of the blading, where the radial flow is almost negligible. Contrastingly, the flow in the endwall and tip regions of the blading is highly three-dimensional, characterised by boundary layer effects, secondary flow features and interaction with cooling flows. Engine designers employ geometric contouring of the endwall region in order to reduce secondary flow effects and subsequently minimise their contribution to aerodynamic loss. Such is the geometric variation of vane and blade profiles — which has become a proprietary art form — the specification of an effective endwall geometry is equally unique to each blade-row. Endwall design methods, which are often directly coupled to aerodynamic optimisers, are widely developed to assist with the generation of contoured surfaces. Most of these construction methods are limited to the blade-row under investigation, while few demonstrate the controllability required to offer a universal platform for endwall design. This paper presents a Geometry Generation Framework (GGF) for the generation of contoured endwalls. The framework employs an adaptable meshing strategy, capable of being applied to any vane or blade, and a versatile function-based approach to defining the endwall shape. The flexibility of this novel approach is demonstrated by recreating a selection of endwalls from the literature, which were selected for their wide-range of contouring approaches.

The exploitation of three-dimensional flow in turbomachinery design

1998 ◽  
Vol 213 (2) ◽  
pp. 125-137 ◽  
Author(s):  
J. D. Denton ◽  
L Xu
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Field Calculation ◽  
3D Flow ◽  
Three Dimensional Flow ◽  
Approximate Methods ◽  
Blade Row ◽  
3D Effects ◽  
Flow Effects ◽  
Turbomachinery Design

Many of the phenomena involved in turbomachinery flow can be understood and predicted on a two-dimensional (2D) or quasi-three-dimensional (Q3D) basis, but some aspects of the flow must be considered as fully three-dimensional (3D) and cannot be understood or predicted by the Q3D approach. Probably the best known of these fully 3D effects is secondary flow, which can only be predicted by a fully 3D calculation which includes the vorticity at inlet to the blade row. It has long been recognized that blade sweep and lean also produce fully 3D effects and approximate methods of calculating these have been developed. However, the advent of fully 3D flow field calculation methods has made predictions of these complex effects much more readily available and accurate so that they are now being exploited in design. This paper will attempt to describe and discuss fully 3D flow effects with particular reference to their use to improve turbomachine performance. Although the discussion is restricted to axial flow machines, many of the phenomena discussed are equally applicable to mixed and radial flow turbines and compressors.

scholarly journals A Simplified Method for 3-D Potential Flow in Turbomachinery Using Vortex Sheet Boundary Conditions

1987 ◽  
Author(s):  
H. Jiang ◽  
R. Cai ◽  
Y. Zhu
Keyword(s):  
Boundary Conditions ◽  
Potential Flow ◽  
Three Dimensional ◽  
Vortex Sheet ◽  
Inviscid Flow ◽  
Three Dimensional Flow ◽  
Blade Row ◽  
Simplified Method ◽  
Outlet Flow ◽  
Two Sides

Within the framework of inviscid flow theory, the character of three-dimensional flow in turbomachinery blade row is discussed. One of the important differences between 3-D and 2-D flow in turbomachinery is the discontinuity of velocity at the two sides of trailing edge and across downstream boundary. The inconsistency of the traditional periodicity conditions for downstream boundary and of the axisymmetric assumption for outlet flow with the three-dimensionality of turbomachinery flow is discussed also. For 3-D potential flow, the vortex sheet boundary conditions (VSBC) for downstream boundary and a fully 3-D condition for outlet flow are presented. A simplified method is developed by implementation of VSBC on a fixed vortex boundary in order to predict the fully 3-D flow in blade passage as well as downstream of blade row. In the present investigation two calculations are carried out. In one calculation the traditional boundary conditions are imposed while in another one the VSBC are used to demonstrate the capability of the newly develped boundary conditions. The agreement between some calculated results and the theoretical analysis is very well.

Aerodynamic Design and Test Result Analysis of a Three Stage Research Compressor

2004 ◽  
Author(s):  
Armel Touyeras ◽  
Michel Villain
Keyword(s):  
Cfd Simulation ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Aerodynamic Design ◽  
New Developments ◽  
Compressor Performance ◽  
Flow Effects ◽  
Stage Matching ◽  
Result Analysis ◽  
Test Result

The present paper describes the aerodynamic design and the test result analysis of a three-stage research compressor designed by Snecma Moteurs and tested at Ecole Centrale de Lyon, France. Firstly, the CREATE compressor, representative of the median or rear stages of modern high-pressure compressors, is presented. Particular emphasis is put on the CFD process employed in its design, which was based largely on three-dimensional Navier-Stokes multistage simulations. A brief description of the stage-by-stage matching achieved on the compressor is also presented. Test results available from traversal probes and laser velocimetry are compared with CFD simulation for overall compressor performance, stage-by-stage matching, and secondary flow effects. Prediction of the design and off-design compressor performance with 3D multistage tools is discussed. Finally, the prospects of new developments concerning the CFD tools and the evolution of the experimental compressor are also mentioned.

Computational Analysis of Pitch-Width Effects on the Secondary Flows of Turbine Blades

2002 ◽  
Author(s):  
C. Xu ◽  
R. S. Amano ◽  
B. Marini
Keyword(s):  
Secondary Flow ◽  
Turbine Blade ◽  
Compressible Flows ◽  
Turbine Blades ◽  
Time Derivative ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Width Ratio ◽  
Blade Row ◽  
Flow Effects

A three-dimensional computational code was developed for solving time-averaged flows within a turbine blade row using a novel time-marching method. A concept of incorporating dissipation terms into the time derivative terms was proposed to allow the code to have the capability of handling both incompressible and compressible flows. The code was validated by comparing the computational results with experiments in a turbine stator blade passage. The code was further used to investigate the influence of secondary flow in a turbine blade row due to different pitch-width ratios. Detailed secondary flows as well as loss profiles in different sizes of root pitch-width ratio are presented and discussed. The results of this study provide useful information for evaluation of the secondary flow effects due to the pitch-width ratio influence for the future new turbine blade designs.

Full Potential Solution of Transonic Quasi-Three-Dimensional Flow Through a Cascade Using Artificial Compressibility

1982 ◽  
Vol 104 (1) ◽  
pp. 143-153 ◽  
Author(s):  
C. Farrell ◽  
J. Adamczyk
Keyword(s):  
Reliable Method ◽  
Three Dimensional ◽  
Full Potential ◽  
Three Dimensional Flow ◽  
Artificial Compressibility ◽  
Dimensional Flow ◽  
Blade Row ◽  
Flow Through ◽  
Transonic Region ◽  
Good Agreement

A reliable method is presented for calculating the flowfield about a cascade of arbitrary two-dimensional airfoils. The method approximates the three-dimensional flow in a turbomachinery blade row by correcting for streamtube convergence and radius change in the throughflow direction. The method is a fully conservative solution of the full potential equation incorporating the finite volume technique on a body-fitted periodic mesh, with an artificial density imposed in the transonic region to ensure stability and the capture of shock waves. Comparison of results for several supercritical blades shows good agreement with their hodograph solutions. Other calculations for these profiles as well as standard NACA blade sections indicate that this is a useful scheme for analyzing both the design and off-design performance of turbomachinery blading.

scholarly journals Analysis of Vortices in Three-Dimensional Jets Introduced in a Cross-Flow Boundary-Layer

1997 ◽  
Author(s):  
O. Sgarzi ◽  
F. Leboeuf
Keyword(s):  
Flow Analysis ◽  
Three Dimensional ◽  
Cross Flow ◽  
Windward Side ◽  
Test Case ◽  
Main Stream ◽  
Viscous Effects ◽  
Vortical Structures ◽  
Jet In Crossflow ◽  
Downstream Flow

The aim of this work is to numerically investigate the different vortical structures present in the flow generated by a jet in crossflow. The test case which is relevant to an hydraulic experiment consists of a single jet ejecting normally into a laminar main stream. The computation is performed using a stationary three-dimensional Navier-Stokes code. A multi-block technique is used to compute the flow in the injection pipe. In addition high resolution is achieved in the region of jet-mainstream interaction. The flow analysis relies on the visualization of particle trajectories. These particles are introduced into vortex cores that are located by the secondary velocity field they induce. The three-dimensional behavior of these structures is enlightened. This provides us with the origin of the fluid of which they are comprised. The mixing between the jet and the incoming viscous layer appears to begin on the windward side of the jet boundary. Up to five types of vortices are identified including the well known counter rotating vortices that dominate the downstream flow. They clearly result from the stretching and warping of the annular vorticity rings issuing from the pipe. At the jet exit, they each split into two sub-structures with different growth and downstream development. Less prominent structures are also seen. The “horse shoe” vortex has been captured which is typical of the near wall effects due to blockage induced by the jet in the main stream. Its downstream legs are sucked through the jet boundary. Another weak structure located on the upstream jet boundary is the “lip” vortex which results from the upstream part of the flow specific topology. It is shown that viscous effects play an important role in both the generation and interaction between vortical structures.

A Geometry Generation Framework for Contoured Endwalls

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Liam E. Wood ◽  
Robin R. Jones ◽  
Oliver J. Pountney ◽  
James A. Scobie ◽  
D. Andrew S. Rees ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Construction Methods ◽  
Novel Approach ◽  
Wide Range ◽  
Blade Row ◽  
Flow Features ◽  
Flow Effects ◽  
Geometric Variation

Abstract The mainstream, or primary, flow in a gas turbine annulus is characteristically two-dimensional over the midspan region of the blading, where the radial flow is almost negligible. Contrastingly, the flow in the endwall and tip regions of the blading is highly three-dimensional (3D), characterized by boundary layer effects, secondary flow features, and interaction with cooling flows. Engine designers employ geometric contouring of the endwall region in order to reduce secondary flow effects and subsequently minimize their contribution to aerodynamic loss. Such is the geometric variation of vane and blade profiles—which has become a proprietary art form—the specification of an effective endwall geometry is equally unique to each blade row. Endwall design methods, which are often directly coupled to aerodynamic optimizers, are widely developed to assist with the generation of contoured surfaces. Most of these construction methods are limited to the blade row under investigation, while few demonstrate the controllability required to offer a universal platform for endwall design. This paper presents a geometry generation framework (GGF) for the generation of contoured endwalls. The framework employs an adaptable meshing strategy, capable of being applied to any vane or blade, and a versatile function-based approach to defining the endwall shape. The flexibility of this novel approach is demonstrated by recreating a selection of endwalls from the literature, which were selected for their wide range of contouring approaches.

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