Time-Dependent Predictions and Analysis of Turbine Cascade Data in the Transonic Flow Region

1993 ◽  
pp. 289-308 ◽  
Author(s):  
A. Bölcs ◽  
A. Cargill ◽  
T. H. Fransson ◽  
A. Suddhoo ◽  
K. Vogeler
Keyword(s):  
Transonic Flow ◽  
Flow Region ◽  
Time Dependent ◽  
Turbine Cascade

Self-Excited Oscillation of Transonic Flow Around an Airfoil in Two-Dimensional Channel

1989 ◽  
Author(s):  
Kazuomi Yamamoto ◽  
Yoshimichi Tanida
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Transonic Flow ◽  
Stokes Equations ◽  
Flow Region ◽  
Boundary Layer Separation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Layer Separation ◽  
Excited Oscillation

A self-excited oscillation of transonic flow in a simplified cascade model was investigated experimentally, theoretically and numerically. The measurements of the shock wave and wake motions, and unsteady static pressure field predict a closed loop mechanism, in which the pressure disturbance, that is generated by the oscillation of boundary layer separation, propagates upstream in the main flow and forces the shock wave to oscillate, and then the shock oscillation disturbs the boundary layer separation again. A one-dimensional analysis confirms that the self-excited oscillation occurs in the proposed mechanism. Finally, a numerical simulation of the Navier-Stokes equations reveals the unsteady flow structure of the reversed flow region around the trailing edge, which induces the large flow separation to bring about the anti-phase oscillation.

Turbulence Evaluation Within the Secondary Flow Region of a Turbine Cascade

1992 ◽  
Author(s):  
D. G. Gregory-Smith ◽  
Th. Biesinger
Keyword(s):  
Large Scale ◽  
Energy Equation ◽  
Three Dimensional ◽  
Flow Region ◽  
Velocity Fields ◽  
Navier Stokes ◽  
Turbine Cascade ◽  
Mean Velocity ◽  
Turbulent Kinetic Energy Equation ◽  
Transition Modelling

Three-dimensional turbulent and mean velocity fields have been measured within a large-scale axial turbine cascade. The results indicate a complex turbulent flow field especially within the secondary vortex. The turbulence is shown to he significantly non-isotropic, and the production and dissipation terms in the turbulent kinetic energy equation have been evaluated in order to illustrate the unusual turbulence behaviour. Comparisons with a Navier-Stokes computation indicate areas for improvement in turbulence and transition modelling.

Computation of the Unsteady Transonic Flow in Harmonically Oscillating Turbine Cascades Taking Into Account Viscous Effects

1996 ◽  
Author(s):  
B. Grüber ◽  
V. Carstens
Keyword(s):  
Transonic Flow ◽  
Splitting Method ◽  
Euler Method ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Implicit Time ◽  
Test Case ◽  
Turbine Cascade ◽  
Viscous Effects ◽  
Unsteady Pressure

This paper presents the numerical results of a code for computing the unsteady transonic viscous flow in a two-dimensional cascade of harmonically oscillating blades. The flow field is calculated by a Navier-Stokes code, the basic features of which are the use of an upwind flux vector splitting scheme for the convective terms (Advection Upstream Splitting Method), an implicit time integration and the implementation of a mixing length turbulence model. For the present investigations two experimentally investigated test cases have been selected in which the blades had performed tuned harmonic bending vibrations. The results obtained by the Navier-Stokes code are compared with experimental data, as well as with the results of an Euler method. The first test case, which is a steam turbine cascade with entirely subsonic flow at nominal operating conditions, is the fourth standard configuration of the “Workshop on Aeroelasticity in Turbomachines”. Here the application of an Euler method already leads to acceptable results for unsteady pressure and damping coefficients and hence this cascade is very appropriate for a first validation of any Navier-Stokes code. The second test case is a highly-loaded gas turbine cascade operating in transonic flow at design and off-design conditions. This case is characterized by a normal shock appearing on the rear part of the blades’s suction surface, and is very sensitive to small changes in flow conditions. When comparing experimental and Euler results, differences are observed in the steady and unsteady pressure coefficients. The computation of this test case with the Navier-Stokes method improves to some extent the agreement between the experiment and numerical simulation.

The Use of Holographic Interferometry for Turbomachinery Fan Evaluation During Rotating Tests

1988 ◽  
Vol 110 (3) ◽  
pp. 393-400 ◽  
Author(s):  
R. J. Parker ◽  
D. G. Jones
Keyword(s):  
Boundary Layer ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Flow Region ◽  
Vibration Modes ◽  
Design Intent ◽  
Tip Leakage ◽  
Fan Behavior ◽  
Boundary Layer Interaction ◽  
Flow Features

Holography has been developed by Rolls-Royce as a technique for routine use in the evaluation of fan designs for aeroengines. It is used to investigate both aerodynamic and mechanical behavior of the rotating fan. Holographic flow visualization provides clear, three-dimensional images of the transonic flow region between the fan blades. Flow features such as shocks, shock/boundary layer interaction, and over-tip leakage vortices can be observed and measured. Holograms taken through an optical derotator allow vibration modes of the rotating fan to be mapped during resonance or flutter. Examples are given of the use of both techniques at rotational speeds up to and in excess of 10,000 rpm. Holography has provided valuable information used to verify and improve numerical modeling of the fan behavior and has been successful in evaluating the achievement of design intent.

A Non-Orthogonal Numerical Method for Solving Transonic Cascade Flows

1976 ◽  
Author(s):  
P. R. Dodge
Keyword(s):  
Analytical Approach ◽  
Time Dependent ◽  
Grid System ◽  
Turbine Cascade ◽  
Relaxation Methods ◽  
Tentative Conclusion ◽  
Characteristic Lines ◽  
Orthogonal Grid ◽  
The Difference ◽  
Transonic Cascade

Recently, external transonic aerodynamic methods have shifted from time-dependent methods to relaxation methods, and have been applied to cascade flows. The results were excellent for supercritical compressor cascades, but for more general transonic conditions, the methods proved inadequate. Detailed studies of a choked turbine cascade and corresponding compressor cascades led to the tentative conclusion that the difficulty was associated with a lack of correspondence between the difference star and differential equation region of influence. The analytical approach developed herein avoids this difficulty by construction of difference stars along a non-orthogonal grid system closely aligned to characteristic lines.

Profile Loss of Ultra-Highly Loaded Turbine Cascade at Transonic Flow Condition

2019 ◽  
Author(s):  
Hoshio Tsujita ◽  
Masanao Kaneko
Keyword(s):  
Mach Number ◽  
Transonic Flow ◽  
Compressible Flows ◽  
Detailed Examination ◽  
Aerodynamic Performance ◽  
Turbine Cascade ◽  
Wide Range ◽  
Exit Mach Number ◽  
Profile Loss ◽  
Highly Loaded

Abstract The aerodynamic performance of turbine components constituting the gas turbine engine is seriously required to be improved in order to reduce environmental load. The energy recovery efficiency in turbine component can be enhanced by the increase of turbine blade loading. In this study, as the first stage to investigate the aerodynamic performance of an ultra-highly loaded turbine cascade (UHLTC) with a turning angle of 160 degrees at transonic flow regime, two-dimensional steady compressible flows in UHLTC were analyzed numerically by using a commercial CFD code to focus on the profile loss. In the computations, the isentropic exit Mach number was varied in the wide range from 0.3 to 1.8 in order to examine the effects of exit Mach number on the shock wave formation and the associated profile loss generation. The computed results were examined in detail by comparing with those for a typical transonic turbine cascade. The detailed examination for the present computed results clarified the variation of shock pattern with the increase of exit Mach number and the loss “plateau” behavior in the present UHLTC.

Sign in / Sign up

Export Citation Format

Share Document