scholarly journals Aeroloads and Secondary Flows in a Transonic Mixed Flow Turbine Stage

1992 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach ◽  
Cass Rogo
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Design System ◽  
Turbine Stage ◽  
Mixed Flow ◽  
Nozzle Vane ◽  
Highly Loaded

A numerical simulation of a transonic mixed flow turbine stage has been carried out using an average passage Navier-Stokes analysis. The mixed flow turbine stage considered here consists of a transonic nozzle vane and a highly loaded rotor. The simulation was run at the design pressure ratio and is assessed by comparing results with those of an established throughflow design system. The three-dimensional aerodynamic loads are studied as well as the development and migration of secondary flows and their contribution to the total pressure loss. The numerical results indicate that strong passage vortices develop in the nozzle vane, mix out quickly, and have little impact on the rotor flow. The rotor is highly loaded near the leading edge. Within the rotor passage, strong spanwise flows and other secondary flows exist along with the tip leakage vortex. The rotor exit loss distribution is similar in character to that found in radial inflow turbines. The secondary flows and non-uniform work extraction also tend to significantly redistribute a non-uniform inlet total temperature profile by the exit of the stage.

Aeroloads and Secondary Flows in a Transonic Mixed-Flow Turbine Stage

1993 ◽  
Vol 115 (3) ◽  
pp. 590-600 ◽  
Author(s):  
K. R. Kirtley ◽  
T. A. Beach ◽  
C. Rogo
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Design System ◽  
Turbine Stage ◽  
Mixed Flow ◽  
Nozzle Vane ◽  
Highly Loaded

A numerical simulation of a transonic mixed-flow turbine stage has been carried out using an average passage Navier–Stokes analysis. The mixed-flow turbine stage considered here consists of a transonic nozzle vane and a highly loaded rotor. The simulation was run at the design pressure ratio and is assessed by comparing results with those of an established throughflow design system. The three-dimensional aerodynamic loads are studied as well as the development and migration of secondary flows and their contribution to the total pressure loss. The numerical results indicate that strong passage vortices develop in the nozzle vane, mix out quickly, and have little impact on the rotor flow. The rotor is highly loaded near the leading edge. Within the rotor passage, strong spanwise flows and other secondary flows exist along with the tip leakage vortex. The rotor exit loss distribution is similar in character to that found in radial inflow turbines. The secondary flows and nonuniform work extraction also tend to redistribute a nonuniform inlet total temperature profile significantly by the exit of the stage.

Design of a Highly Loaded Transonic Two-Stage Fan Using Swept and Bowed Blading

2011 ◽  
Author(s):  
Hailiang Jin ◽  
Donghai Jin ◽  
Fang Zhu ◽  
Ke Wan ◽  
Xingmin Gui
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Two Stage ◽  
Stall Margin ◽  
Stator Vane ◽  
Total Pressure Ratio ◽  
Highly Loaded

This paper presents the design of a highly loaded transonic two-stage fan using several advanced three-dimensional blading techniques including forward sweep and “hub bending” in rotors and several bowed configurations in stators. The effects of these blading techniques on the performance of the highly loaded transonic two-stage fan were investigated on the basis of three-dimensional Navier-Stokes predictions. The results indicate that forward sweep has insignificant impact on the total pressure ratio and adiabatic efficiency of the fan. The throttling range of the fan is found to be improved by forward sweep because the shock in the forward swept rotor is expelled later upstream to the leading edge than that in the unswept one. Hub bending design technique increases the efficiency in the hub region of R1 due to the reduction of the low momentum zone in the hub region near the trailing edge. The stator vane design has a pronounced impact on the performance of the fan. The total pressure ratio, adiabatic efficiency, and stall margin of the schemes with the bowed vanes are increased significantly compared to the scheme with the straight vanes. The large corner stall in the straight S1 vane is reduced effectively by the bowed S1 vanes. Moreover, the strong corner stall in the straight S2 vane is fully eliminated by the bowed S2 vanes. Among the bowed vane schemes, the scheme with positive bowed (P. B.) hub and negative bowed (N. B.) tip vanes has the best efficiency and stall margin performances thanks to the superiority of the performance over the midspan regions of the bowed vanes.

scholarly journals Study of Internal Flows in a Mixed-Flow Pump Impeller at Various Tip Clearances Using 3D Viscous Flow Computations

1990 ◽  
Author(s):  
Akira Goto
Keyword(s):  
Reverse Flow ◽  
Three Dimensional ◽  
Interaction Mechanism ◽  
Secondary Flows ◽  
Wake Flow ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Flow Pump

The complex three-dimensional flow fields in a mixed-flow pump impeller are investigated by applying the incompressible version of the Dawes’ 3D Navier-Stokes code. The applicability of the code is confirmed by comparison of computations with a variety of experimentally measured jet-wake flow patterns and overall performances at four different tip clearances including the shrouded case. Based on the computations, the interaction mechanism of secondary flows and the formation of jet-wake flow are discussed. In the case of large tip clearances, the reverse flow caused by tip leakage flow is considered to be the reason for the thickening of the casing boundary layer followed by the deterioration of the whole flow field.

Influences of Axial Gap Between Blade Rows on Secondary Flows and Aerodynamic Performance in a Turbine Stage

2009 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
M. Kikuchi ◽  
H. Sato
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Axial Direction ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Turbine Stage ◽  
Stator Vane ◽  
Is Design ◽  
Probe Measurements

A study on the effects of the axial gap between stator and rotor upon the stage performance and flow field of a single axial flow turbine stage is presented in this paper. Three axial gaps were tested, which were achieved by moving the stator vane in the axial direction while keeping the disk cavity constant. The effect of the axial gap was investigated at two different conditions, that is design and off-design conditions. The unsteady three-dimensional flow field was analyzed by time-accurate RANS (Reynolds-Averaged Navier-Stokes) simulations. The simulation results were compared with the experiments, in which total pressure and the time-averaged flow field upstream and downstream of the rotor were obtained by five-hole probe measurements. The effect of the axial gap was confirmed in the endwall regions, and obtained relatively at off-design condition. The turbine stage efficiency was improved almost linearly by reducing the axial gap at the off-design condition.

Nonaxisymmetric Turbine End Wall Design: Part I— Three-Dimensional Linear Design System

1999 ◽  
Vol 122 (2) ◽  
pp. 278-285 ◽  
Author(s):  
Neil W. Harvey ◽  
Martin G. Rose ◽  
Mark D. Taylor ◽  
Shahrokh Shahpar ◽  
Jonathan Hartland ◽  
...  
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Design System ◽  
Linear Superposition ◽  
Turbine Rotor Blade ◽  
End Wall

A linear design system, already in use for the forward and inverse design of three-dimensional turbine aerofoils, has been extended for the design of their end walls. This paper shows how this method has been applied to the design of a nonaxisymmetric end wall for a turbine rotor blade in linear cascade. The calculations show that nonaxisymmetric end wall profiling is a powerful tool for reducing secondary flows, in particular the secondary kinetic energy and exit angle deviations. Simple end wall profiling is shown to be at least as beneficial aerodynamically as the now standard techniques of differentially skewing aerofoil sections up the span, and (compound) leaning of the aerofoil. A design is presented that combines a number of end wall features aimed at reducing secondary loss and flow deviation. The experimental study of this geometry, aimed at validating the design method, is the subject of the second part of this paper. The effects of end wall perturbations on the flow field are calculated using a three-dimensional pressure correction based Reynolds-averaged Navier–Stokes CFD code. These calculations are normally performed overnight on a cluster of work stations. The design system then calculates the relationships between perturbations in the end wall and resulting changes in the flow field. With these available, linear superposition theory is used to enable the designer to investigate quickly the effect on the flow field of many combinations of end wall shapes (a matter of minutes for each shape). [S0889-504X(00)00902-8]

FLOW FIELD ANALYSIS OF AN AUTOMOTIVE MIXED FLOW TURBOCHARGER TURBINE

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
M. H. Padzillah ◽  
S. Rajoo ◽  
R. F. Martinez-Botas
Keyword(s):  
Optimum Condition ◽  
Flow Field ◽  
Internal Combustion Engines ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Field Analysis ◽  
Turbine Stage ◽  
Mixed Flow ◽  
Geometrical Properties

Traditionally, the turbocharger has been an essential tool to boost the engine power especially the diesel engine. However, in recent years it is seen as an enabling technology for engine downsizing of all internal combustion engines. The use of mixed flow turbine as replacement for radial turbine in an automotive turbocharger has been proven to deliver better efficiency at high loading conditions. Furthermore, the use vanes that match the geometrical properties at the turbine leading edge could further increase its performance. However, improvement on the overall turbocharger performance is currently limited due to lack of understanding on the flow feature within the turbine stage. Therefore, the use of validated Computational Fluid Dynamics (CFD) in resolving this issue is necessary. This research attempts to provide description of flow field within the turbocharger turbine stage by plotting velocity and pressure contours at different planes. To achieve this aim, a numerical model of a full stage turbocharger turbine operating at 30000rpm under its optimum condition (pressure ratio of 1.3) is developed and validated. Results indicated strong tip-clearance flow downstream of the turbine mid-chord. Evidence of flow separations at the turbine leading edge are also seen despite turbine operating at its optimum condition.

A Deep Insight Into the Transonic Flow of an Advanced Centrifugal Compressor Design

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
David Wittrock ◽  
Martin Junker ◽  
Manfred Beversdorff ◽  
Andreas Peters ◽  
Eberhard Nicke
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Free Form ◽  
Numerical Verification ◽  
Deep Insight ◽  
Compressor Design ◽  
Design Speed

Abstract In the last decades, major improvements in transonic centrifugal compressor design have been achieved. The further exploration of design space is enabled by recent progress in structural mechanics and manufacturing. A challenging task of inducer design especially in terms of transonic inflow conditions is to provide a wide flow range and reduced losses due to a sufficient shock control. The use of so-called multidisciplinary design optimization with an extensive amount of free parameters leads finally to complex designs. DLR’s latest fast rotating centrifugal compressor (SRV5) operates at a design speed of Mu2 = 1.72 and a total pressure ratio of 5.72. This compressor design is characterized by an S-shaped leading edge and free-form blade surfaces. Due to the complex design, the key design features are difficult to explore. Therefore, nonintrusive measurements are conducted on the highly loaded SRV5. The laser-2-focus (L2F) approach that is used in addition with the doppler-global-velocimetry (DGV) delivers a three-dimensional velocity field. Besides the impeller inflow, the outflow is also part of the experimental and numerical verification of the advanced compressor design. Experimental results are compared with the numerical analysis of the compressor using DLR’s Reynolds-averaged Navier–Stokes Flow Solver TRACE. The deep insight of the inflow leads to a better understanding of the operating behavior of such impeller designs.

scholarly journals Non-Axisymmetric Turbine End Wall Design: Part I — Three-Dimensional Linear Design System

1999 ◽  
Author(s):  
Neil W. Harvey ◽  
Martin G. Rose ◽  
Mark D. Taylor ◽  
Shahrokh Shahpar ◽  
Jonathan Hartland ◽  
...  
Keyword(s):  
Flow Field ◽  
Design Method ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Design System ◽  
Linear Superposition ◽  
Turbine Rotor Blade ◽  
End Wall

A linear design system, already in use for the forward and inverse design of three-dimensional turbine aerofoils, has been extended for the design of their end walls. This paper shows how this method has been applied to the design of a non-axisymmetric end wall for a turbine rotor blade in linear cascade. The calculations show that non-axisymmetric end wall profiling is a powerful tool for reducing secondary flows, in particular the secondary kinetic energy and exit angle deviations. Simple end wall profiling is shown to be at least as beneficial aerodynamically as the now standard techniques of differentially skewing aerofoil sections up the span, and (compound) leaning of the aerofoil. A design is presented which combines a number of end wall features aimed at reducing secondary loss and flow deviation. The experimental study of this geometry, aimed at validating the design method, is the subject of the second part of this paper. The effects of end wall perturbations on the flow field are calculated using a 3-D pressure correction based Reynolds Averaged Navier-Stokes CFD code. These calculations are normally performed overnight on a cluster of work stations. The design system then calculates the relationships between perturbations in the end wall and resulting changes in the flow field. With these available, linear superposition theory is used to enable the designer to investigate quickly the effect on the flow field of many combinations of end wall shapes (a matter of minutes for each shape).

Investigation of the Flowfield in the Transonic VKI BRITE EURAM Turbine Stage With 3D Steady and Unsteady N-S Computations

2000 ◽  
Author(s):  
Björn Laumert ◽  
Hans Mårtensson ◽  
Torsten H. Fransson
Keyword(s):  
Rotor Blade ◽  
Three Dimensional ◽  
Leading Edge ◽  
Weak Shock ◽  
Suction Side ◽  
Navier Stokes ◽  
Turbine Stage ◽  
Trailing Edge ◽  
Measured Pressure ◽  
Good Agreement

This paper presents the results from three-dimensional (3D) steady and unsteady Navier-Stokes computations, performed on the transonic VKI BRITE EURAM test turbine stage. The work aimed at giving deeper insight in the aerodynamics of the turbine stage. The analysis has been carried out with the nominal stator trailing edge ejection slot geometry and cooling flow ejection. Additionally a simplified rounded stator trailing edge was employed. The results from the unsteady computations were compared with measured pressure perturbation traces at 22 locations around the rotor blade at midspan. Computations with both the ejection slot and the rounded stator trailing edge geometry were in good agreement with the measurements on the pressure side and half chord of the rotor blade’s suction side. Measurements and computations showed less good agreement downstream a weak shock on the suction side of the rotor blade. The measured pressure double peak in the rotor blade leading edge region is only observed in the computations with the ejection slot geometry.

Study of Internal Flows in a Mixed-Flow Pump Impeller at Various Tip Clearances Using Three-Dimensional Viscous Flow Computations

1992 ◽  
Vol 114 (2) ◽  
pp. 373-382 ◽  
Author(s):  
A. Goto
Keyword(s):  
Reverse Flow ◽  
Three Dimensional ◽  
Interaction Mechanism ◽  
Secondary Flows ◽  
Wake Flow ◽  
Navier Stokes ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Flow Pump

The complex three-dimensional flow fields in a mixed-flow pump impeller are investigated by applying the incompressible version of Dawes’ Three-Dimensional Navier–Stokes code. The applicability of the code is confirmed by comparison of computations with a variety of experimentally measured jet-wake flow patterns and overall performances at four different tip clearances, including the shrouded case. Based on the computations, the interaction mechanism of secondary flows and the formation of jet-wake flow are discussed. In the case of large tip clearances, the reverse flow caused by tip leakage flow is considered to be the reason for the thickening of the casing boundary layer followed by the deterioration of the whole flow field.

Sign in / Sign up

Export Citation Format

Share Document