Speed Line Computation of a Transonic Compressor Stage With Unsteady CFD Methods

2012 ◽  
Author(s):  
Thomas Biesinger ◽  
Christian Cornelius ◽  
Dirk Nürnberger ◽  
Christoph Rube
Keyword(s):  
Measurement Data ◽  
Shock Propagation ◽  
Compressor Stage ◽  
Transient Time ◽  
Transonic Compressor ◽  
Lower Back ◽  
Unsteady Simulation ◽  
Flow Through ◽  
Unsteady Effects ◽  
Blade Row Interaction

The flow through a transonic compressor stage is dominated by unsteady effects such as shock propagation and wake shedding. An accurate prediction of the performance of a compressor, i.e. operating range and efficiency, may require the modeling of unsteady effects. Steady CFD methods cease to converge too early when the stall limit is approached. Efficient unsteady CFD methods such as the transient time-inclining (TI) method and the perturbation based non-linear harmonic (NLH) method perform better and are becoming increasingly popular in the industry. Both methods consider the actual blade count ratio for each passage while using a single passage model. The main objective of this paper is to explain these methods and benchmark their performance with respect to reliable near stall predictions. Computed compressor characteristics and blade row interaction effects of the Purdue Transonic Research Compressor are compared to measurement data. The stator row is found to be limited at the casing in all of the unsteady simulation results. This effect is also qualitatively predicted by steady results calculated at a lower back pressure level. The NLH method is significantly faster than the other transient methods and the TI method resolves more flow detail on identical meshes.

scholarly journals Influence of Unsteady Effects on the Measurements in a Transonic Axial Compressor

1991 ◽  
Author(s):  
Jacques Paulon ◽  
Zhifang Zhang ◽  
Pingfang Jia ◽  
Jingfei Meng
Keyword(s):  
Flow Field ◽  
Relative Position ◽  
Axial Compressor ◽  
Compressor Stage ◽  
Transonic Compressor ◽  
Flow Parameters ◽  
Transonic Axial Compressor ◽  
Unsteady Effects ◽  
Computation Codes ◽  
Interaction Phenomena

Interaction phenomena between rotor and stator are unavoidable in advanced compressors and their effects increase with the performances of the turbomachines. Until now, it was not possible to quantify the interaction effects, but with the development of 3-D unsteady computation codes in a complete stage, it is possible to know, in detail, the flow field through the machine and to make evident and to explain the difficulties encountered in measuring the flow parameters. A study has been conducted in this way at ONERA, on an axial transonic compressor stage. The computations have been made with a simulation of the losses; in this manner, the overall computed and measured performances of the compressor are the same. A detailed analysis of the unsteady computation results makes evident, between rotor and stator, large variations of some parameters of the flow as a function of time but also as a function of the axial and tangential relative position of steady probes and stator blades. Unsteady measurements made on another transonic machine confirm the indications given by these computations.

scholarly journals Deterministic Stress Modeling for Multistage Compressor Flowfields

2013 ◽  
Author(s):  
Stefan Stollenwerk ◽  
Edmund Kügeler
Keyword(s):  
Gas Turbines ◽  
Transport Model ◽  
Navier Stokes ◽  
Transonic Compressor ◽  
Wide Range ◽  
Multistage Compressor ◽  
Aero Engines ◽  
Unsteady Effects ◽  
Stress Models ◽  
Blade Row Interaction

Unsteadiness is one of the main characteristics in turbomachinery flows. Local unsteady changes in static pressure must exist within a turbo-machine in order for that machine to exchange energy with the fluid. The primary reason for unsteady effects lies in the interaction between moving and stationary blade rows. The industrial design process of aero-engines and gas turbines is still based on Reynolds-averaged Navier-Stokes (RANS) techniques where the coupling of blade rows is carried out by mixing-planes. However, this methodology does not cover deterministic unsteadiness in an adequate way. For standard aero-optimization, detailed unsteadiness is not essential to the designer of turbomachines but rather its effect on the time averaged solution. The time averaged deterministic unsteadiness can be expressed in terms of deterministic stresses. The present paper presents two different modeling strategies for deterministic stresses that constitute an improvement of the conventional steady mixing-plane approach. Whilst one of the presented models operates with deterministic flux terms based on preliminary unsteady simulations, the other one, a novel transport model for deterministic stress, is a stand-alone approach based on empirical correlations and a wide range of numerical experiments. A 4.5 stage transonic compressor is analyzed regarding blade row interaction effects and their impact on the time averaged solution. The two models are applied to the compressor and their solutions are compared to conventional mixing-plane, time accurate and experimental data. The results for the speedline, the wake shapes, the radial distributions and the rotor blade loadings show that the deterministic stress models strongly improve the RANS solution towards the time accurate and the experimental methods.

scholarly journals Effect of Rotor–Stator Interaction on Impeller Performance in Centrifugal Compressors

1999 ◽  
Vol 5 (2) ◽  
pp. 135-146 ◽  
Author(s):  
K. Sato ◽  
L. He
Keyword(s):  
Navier Stokes ◽  
Test Case ◽  
Steady Flows ◽  
Centrifugal Compressors ◽  
Vaned Diffuser ◽  
Rotor Stator Interaction ◽  
Flow Through ◽  
And Performance ◽  
Unsteady Effects ◽  
Blade Row Interaction

A 3-D unsteady thin-layer Navier-Stokes code has been used to calculate the flow through a centrifugal compressor stage. The validation of the code for steady flows in centrifugal compressors was conducted for the Krain’s impeller with a vaneless diffuser as a test case and the numerical results were compared with the experimental results. The predicted flow field and performance agreed well with the experimental data. An unsteady stage solution was then conducted with this impeller followed by a generic low-solidity vaned-diffuser to examine the unsteady effects on the impeller performance. The computational results showed a stabilising effect of the blade row interaction.

Influence of Unsteady Effects on the Measurements in a Transonic Axial Compressor

1992 ◽  
Vol 114 (3) ◽  
pp. 510-516 ◽  
Author(s):  
J. Paulon ◽  
Zhifang Zhang ◽  
Pingfang Jia ◽  
Jingfei Meng
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Compressor Stage ◽  
Transonic Compressor ◽  
Flow Parameters ◽  
Transonic Axial Compressor ◽  
Unsteady Effects ◽  
Computation Codes ◽  
Interaction Phenomena

Interaction phenomena between rotor and stator are unavoidable in advanced compressors and their effects increase with the performance of the turbomachines. Until now, it was not possible to quantify the interaction effects, but with the development of three-dimensional unsteady computation codes in a complete stage, it is possible to know, in detail, the flow field through the machine and to make evident and to explain the difficulties encountered in measuring the flow parameters. A study has been conducted in this way at ONERA, on an axial transonic compressor stage. The computations have been made with a simulation of the losses; in this manner, the overall computed and measured performances of the compressor are the same. A detailed analysis of the unsteady computation results makes evident, between rotor and stator, large variations of some parameters of the flow as a function of time, but also as a function of the axial and tangential relative position of steady probes and stator blades. Unsteady measurements made on another transonic machine confirm the indications given by these computations.

scholarly journals Blade Row Interaction Effects on the Performance of a Moderately Loaded NASA Transonic Compressor Stage

2002 ◽  
Author(s):  
Dale E. Van Zante ◽  
Wai-Ming To ◽  
Jen-Ping Chen
Keyword(s):  
Experimental Data ◽  
Velocity Field ◽  
Interaction Effects ◽  
Operating Conditions ◽  
Laser Doppler Velocimeter ◽  
Compressor Stage ◽  
Peak Efficiency ◽  
Transonic Compressor ◽  
Blade Row ◽  
Blade Row Interaction

Blade row interaction effects on loss generation in compressors have received increased attention as compressor work-per-stage and blade loading have increased. Two dimensional Laser Doppler Velocimeter measurements of the velocity field in a NASA transonic compressor stage show the magnitude of interactions in the velocity field at the peak efficiency and near stall operating conditions. The experimental data are presented along with an assessment of the velocity field interactions. In the present study the experimental data are used to confirm the fidelity of a three-dimensional, time-accurate, Navier Stokes calculation of the stage using the MSU-TURBO code at the peak efficiency and near stall operating conditions. The simulations are used to quantify the loss generation associated with interaction phenomena. At the design point the stator pressure field has minimal effect of the rotor performance. The rotor wakes do have an impact on loss production in the stator passage at both operating conditions. A method for determining the potential importance of blade row interactions on performance is presented.

Forces on Unstaggered Airfoil Cascades in Unsteady In-Phase Motion

1976 ◽  
Vol 98 (3) ◽  
pp. 521-530 ◽  
Author(s):  
N. H. Kemp ◽  
H. Ohashi
Keyword(s):  
Flow Velocity ◽  
Incompressible Flow ◽  
Kutta Condition ◽  
Harmonic Motion ◽  
Thin Airfoil ◽  
Through Flow ◽  
Flow Through ◽  
Unsteady Effects ◽  
Analytical Expressions ◽  
Phase Motion

Incompressible flow through an unstaggered cascade in general, unsteady, in-phase motion is considered. By methods of thin-airfoil theory, using the assumptions of wakes trailing back at the through-flow velocity, and the Kutta condition, exact analytical expressions are derived for loading, lift and moment. As application, harmonic motion is considered for plunging, pitching, and sinusoidal gusts. Numerical values of lift and moment for these three cases are given graphically (tables are available from the authors). The results show strong analogies with isolated unsteady thin-airfoil theory. They should prove useful as simple examples of unsteady effects in cascades, and as check cases for other approximate or purely numerical analyses.

scholarly journals Assessment of the Severity of Unsteady Mach Number Effects in a 3-Stage Transonic Compressor

2017 ◽  
Author(s):  
Anthony Dent ◽  
Liping Xu ◽  
Roger Wells
Keyword(s):  
Leading Edge ◽  
Compressor Stage ◽  
Pressure Potential ◽  
Cfd Simulations ◽  
Transonic Compressor ◽  
Inlet Guide Vanes ◽  
Great Consideration ◽  
Stator Blade ◽  
Front Stage ◽  
Stage Efficiency

In this paper results from steady and unsteady CFD simulations of an industrial transonic compressor are compared, in order to gain a better understanding of the cause of the differences in the predicted efficiencies between the steady and unsteady simulations. Initially the first stage is simulated as an isolated compressor stage with inlet guide vanes in order to analyse the effect of individual blade rows on the stage performance. It is found that the rotor efficiency is lower for steady simulations than for unsteady simulations due to stronger shock waves. The stator efficiency is greater in the steady simulations due to not being able to model the interaction of the rotor wakes with the stator blade leading edge and boundary layers. Greater variation between steady and unsteady predictions is found at higher operating speeds. In the 3-stage unsteady simulations, the front stage efficiency characteristic is the same as the efficiency calculated from the isolated unsteady simulations. This shows that the unsteady pressure potential propagating from the downstream stages has no significant effect on the front stage efficiency meaning that the designer does not need to give great consideration to the downstream blade rows when predicting the characteristics of the front stage.

Sign in / Sign up

Export Citation Format

Share Document