Improving Efficiency of a High Work Turbine Using Nonaxisymmetric Endwalls— Part I: Endwall Design and Performance

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
T. Germain ◽  
M. Nagel ◽  
I. Raab ◽  
P. Schüpbach ◽  
R. S. Abhari ◽  
...  
Keyword(s):  
Axial Flow ◽  
Programming Algorithm ◽  
Navier Stokes ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
Transition Modeling ◽  
And Performance ◽  
High Work ◽  
Sequential Quadratic Programming Algorithm ◽  
Probe Measurements

This paper is the first part of a two part paper reporting the improvement of efficiency of a one-and-half stage high work axial flow turbine by nonaxisymmetric endwall contouring. In this first paper the design of the endwall contours is described, and the computational fluid dynamics (CFD) flow predictions are compared with five-hole-probe measurements. The endwalls have been designed using automatic numerical optimization by means of a sequential quadratic programming algorithm, the flow being computed with the 3D Reynolds averaged Navier-Stokes (RANS) solver TRACE. The aim of the design was to reduce the secondary kinetic energy and secondary losses. The experimental results confirm the improvement of turbine efficiency, showing a stage efficiency benefit of 1%±0.4%, revealing that the improvement is underestimated by CFD. The secondary flow and loss have been significantly reduced in the vane, but improvement of the midspan flow is also observed. Mainly this loss reduction in the first row and the more homogeneous flow is responsible for the overall improvement. Numerical investigations indicate that the transition modeling on the airfoil strongly influences the secondary loss predictions. The results confirm that nonaxisymmetric endwall profiling is an effective method to improve turbine efficiency but that further modeling work is needed to achieve a good predictability.

Improving Efficiency of a High Work Turbine Using Non-Axisymmetric Endwalls: Part I—Endwall Design and Performance

2008 ◽  
Author(s):  
T. Germain ◽  
M. Nagel ◽  
I. Raab ◽  
P. Schuepbach ◽  
R. S. Abhari ◽  
...  
Keyword(s):  
Numerical Optimization ◽  
Axial Flow ◽  
Loss Reduction ◽  
Numerical Investigations ◽  
Turbine Efficiency ◽  
Transition Modeling ◽  
And Performance ◽  
High Work ◽  
Stage Efficiency ◽  
Probe Measurements

This paper is the first part of a two part paper reporting the improvement of efficiency of a one-and-half stage high work axial flow turbine by non-axisymmetric endwall contouring. In this first paper the design of the endwall contours is described and the CFD flow predictions are compared to five-hole-probe measurements. The endwalls have been designed using automatic numerical optimization by means of an Sequential Quadratic Programming (SQP) algorithm, the flow being computed with the 3D RANS solver TRACE. The aim of the design was to reduce the secondary kinetic energy and secondary losses. The experimental results confirm the improvement of turbine efficiency, showing a stage efficiency benefit of 1%±0.4%, revealing that the improvement is underestimated by CFD. The secondary flow and loss have been significantly reduced in the vane, but improvement of the midspan flow is also observed. Mainly this loss reduction in the first row and the more homogeneous flow is responsible for the overall improvement. Numerical investigations indicate that the transition modeling on the airfoil strongly influences the secondary loss predictions. The results confirm that non-axisymmetric endwall profiling is an effective method to improve turbine efficiency, but that further modeling work is needed to achieve a good predictability.

The Design and Performance of a High Work Research Turbine

1996 ◽  
Vol 118 (4) ◽  
pp. 792-799 ◽  
Author(s):  
E. P. Vlasic ◽  
S. Girgis ◽  
S. H. Moustapha
Keyword(s):  
Pressure Ratio ◽  
Limit Load ◽  
Gas Generator ◽  
Part Load ◽  
Cold Flow ◽  
Turbine Efficiency ◽  
Load Pattern ◽  
Design Speed ◽  
And Performance ◽  
High Work

This paper describes the design and performance of a high work single-stage research turbine with a pressure ratio of 5.0, a stage loading of 2.2, and cooled stator and rotor. Tests were carried out in a cold flow rig and as part of a gas generator facility. The performance of the turbine was assessed, through measurements of reaction, rotor exit conditions and efficiency, with and without airfoil cooling. The measured cooled efficiency in the cold rig was 79.9 percent, which, after correcting for temperature and measuring plane location, matched reasonably well the efficiency of 81.5 percent in the gas generator test. The effect of cooling, as measured in the cold rig, was to reduce the turbine efficiency by 2.1 percent. A part-load turbine map was obtained at 100, 110, and 118 percent design speed and at 3.9, 5.0, and 6.0 pressure ratio. The influence of speed and the limit load pattern for transonic turbines are discussed. The effect of the downstream measuring distance on the calculated efficiency was determined using three different locations. An efficiency drop of 3.2 percent was measured between the rotor trailing edge plane and a distance four chords downstream.

An Investigation on Performance of an Asymmetric Twin-Scroll Turbine With a Small Scroll Bypass Wastegate for a Heavy-Duty Diesel Engine

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Jianjiao Jin ◽  
Jianfeng Pan ◽  
Zhigang Lu ◽  
Qingrui Wu ◽  
Lizhong Xu ◽  
...  
Keyword(s):  
Engine Performance ◽  
Performance Tests ◽  
Turbine Efficiency ◽  
Flow Parameters ◽  
Matching Process ◽  
Heavy Duty Diesel Engine ◽  
Computational Fluid Dynamics Cfd ◽  
Heavy Duty Diesel ◽  
And Performance ◽  
Prediction Efficiency

Abstract In this paper, a novel one-dimensional matching method of an asymmetric twin-scroll turbine (ATST) with a small scroll bypass wastegate is initially presented for energy improvement. The developed method presents further insights into efficiency prediction of the ATST and the small scroll exhaust bypass in the matching process of model characterization. The efficiency of the small and large scroll turbines was approximately assessed with two times flow parameters of the small and large scroll turbines, respectively, as well as according to turbine efficiency prediction curves. Subsequently, given the matching results of a 9-L engine, a targeted ATST was developed; its effectiveness was verified by computational fluid dynamics (CFD) and the performance tests of a turbine and an engine. As revealed from the results, the prediction efficiency of the ATST well complies with that of the numerical calculation and performance tests of turbines and engines. Compared with the common large scroll exhaust bypass wastegate, the small one exhibits better engine performance and can save nearly 0.5–1.5% fuel consumption at middle and high engine speeds. Moreover, the reasons of which were explored for better understanding of the mechanism accordingly.

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.

scholarly journals Advancement of Turbine Aerodynamic Design Techniques

1993 ◽  
Author(s):  
Lisa W. Griffin ◽  
Frank W. Huber
Keyword(s):  
Fluid Dynamics ◽  
State Of The Art ◽  
Cfd Analysis ◽  
Aerodynamic Design ◽  
Turbine Efficiency ◽  
Component Design ◽  
Pump Stage ◽  
Computational Fluid Dynamics Cfd ◽  
The Government ◽  
And Performance

The Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology has been created at NASA/MSFC. Its purpose is to advance the state-of-the-art of CFD technology, to validate CFD codes and models, and to demonstrate the benefits attainable through the application of CFD in component design. Three teams are currently active within the Consortium: (1) the Turbine Technology Team, (2) the Pump Stage Technology Team, and (3) the Combustion Devices Technology Team. The goals, dynamics, and activities of the Turbine Team are the subjects of this paper. The Consortium is managed by NASA. The Turbine Team is co-coordinated by a NASA representative from the CFD area and an industry (Pratt & Whitney) representative from the area of turbine aerodynamic design. Membership of the Turbine Team includes experts in design, analysis, and testing from the government, industry, and academia. Each member brings a unique perspective, expertise, and experience to bear on the team’s goals of improving turbine efficiency and robustness while reducing the amount of developmental testing. To this end, an advanced turbine concept has been developed within the team using CFD as an integral part of the design process. This concept employs unconventionally high turning blades and is predicted to provide cost and performance benefits over traditional designs. This concept will be tested in the MSFC Turbine Airflow Facility to verify the design and to provide a unique set of data for CFD code validation. Currently, the team is developing and analyzing methods to reduce secondary and tip losses to further enhance turbine efficiency. The team has also targeted volute development as an area that could benefit from detailed CFD analysis.

Adjoint-Based Multidisciplinary, Multipoint Optimization of a Radial Turbine Considering Aerodynamic and Structural Performances

2019 ◽  
Author(s):  
Lasse Mueller ◽  
Tom Verstraete ◽  
Marc Schwalbach
Keyword(s):  
Mechanical Stresses ◽  
Programming Algorithm ◽  
Navier Stokes ◽  
Analysis Tool ◽  
Element Analysis ◽  
Turbine Efficiency ◽  
Radial Turbine ◽  
Design Variables ◽  
Gradient Based ◽  
Adjoint Approach

Abstract This paper presents a multidisciplinary adjoint-based design optimization of a turbocharger radial turbine for automotive applications. The aim is to improve the total-to-static efficiency of the turbine while keeping mechanical stresses below a predefined limit. The search for the optimal design is accomplished using an efficient Sequential Quadratic Programming algorithm considering additional aerodynamic and manufacturing constraints. The aerodynamic performance of the wheel is evaluated by a Reynolds-Averaged Navier-Stokes solver, whereas the maximum stresses in the material are predicted by a Finite Element Analysis tool. The design gradients required by the optimizer are computed with the adjoint approach which provides sensitivity information largely independent of the number of design variables. The results presented in this paper show the clear need to take into account mechanical stresses during optimization, as they are the most restrictive design limitation. However, the gradient-based optimization algorithm is able to effectively keep the stress levels below the critical value while significantly improving the turbine efficiency in a few design cycles.

scholarly journals MPI to Coarray Fortran: Experiences with a CFD Solver for Unstructured Meshes

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Anuj Sharma ◽  
Irene Moulitsas
Keyword(s):  
High Resolution ◽  
Message Passing ◽  
Message Passing Interface ◽  
Parallel Implementation ◽  
Unstructured Meshes ◽  
Navier Stokes ◽  
Performance Measurements ◽  
Partitioned Global Address Space ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

High-resolution numerical methods and unstructured meshes are required in many applications of Computational Fluid Dynamics (CFD). These methods are quite computationally expensive and hence benefit from being parallelized. Message Passing Interface (MPI) has been utilized traditionally as a parallelization strategy. However, the inherent complexity of MPI contributes further to the existing complexity of the CFD scientific codes. The Partitioned Global Address Space (PGAS) parallelization paradigm was introduced in an attempt to improve the clarity of the parallel implementation. We present our experiences of converting an unstructured high-resolution compressible Navier-Stokes CFD solver from MPI to PGAS Coarray Fortran. We present the challenges, methodology, and performance measurements of our approach using Coarray Fortran. With the Cray compiler, we observe Coarray Fortran as a viable alternative to MPI. We are hopeful that Intel and open-source implementations could be utilized in the future.

Numerical and Experimental Analysis of the Effect of Variable Blade Row Spacing in a Subsonic Axial Turbine

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
M. Restemeier ◽  
P. Jeschke ◽  
Y. Guendogdu ◽  
J. Gier
Keyword(s):  
Axial Flow ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Row Spacing ◽  
Test Rig ◽  
Jet Propulsion ◽  
Turbine Efficiency ◽  
Air Turbine ◽  
Blade Row ◽  
Flow Interactions

Numerical and experimental investigations have been performed to determine the effect of a variation of the interblade row axial gap on turbine efficiency. The geometry used in this study is the 1.5-stage axial flow turbine rig of the Institute of Jet Propulsion and Turbomachinery at Rhejnisch Westfalische Technische Hochshule (RWTH) Aachen University. The influence of the blade row spacing on aerodynamics has been analyzed by conducting steady and unsteady Reynolds-averaged Navier-Stokes (RANS) simulations as well as measurements in the cold air turbine test rig of the Institute. Both potential and viscous flow interactions, including secondary flow, were investigated. The results show an aerodynamic improvement of efficiency and favorable spatial distribution of secondary kinetic energy by reduction of the axial gap.

scholarly journals Mixing Performance of Counter-Axial Flow Impeller using Computational Fluid Dynamics

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
Ian Torotwa ◽  
Changying Ji
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Axial Flow ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ansys Fluent ◽  
Rushton Turbine ◽  
Mixing Performance ◽  
Computational Fluid Dynamics Cfd

In this study, turbulent flow fields in a baffled vessel stirred by counter-axial flow impeller have been investigated in comparison to the Rushton turbine. The resultant turbulence was numerically predicted using computational fluid dynamics (CFD). Turbulence models were developed in ANSYS Fluent 18.1 solver using the Navier-Stokes equation with the standard k-ε turbulence model. The Multiple Reference Frame (MRF) approach was used to simulate the impeller action in the vertical and horizontal planes of the stirred fluid volume. Velocity profiles generated from the simulations were used to predict and compare the performance of the two designs. To validate the CFD model, the simulation results were compared with experimental results from existing work and a satisfactory agreement was established. It was concluded that the counter-axial flow impeller could provide better turbulence characteristics that would improve the quality of mixing systems.

Experimentally Observed Unsteady Work at Inlet to and Exit From an Axial Flow Turbine Rotor

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Martin G. Rose ◽  
Philipp Jenny ◽  
Jochen Gier ◽  
Reza S. Abhari
Keyword(s):  
World Literature ◽  
Axial Flow ◽  
Fast Response ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Work Distribution ◽  
Wake Interaction ◽  
Computational Fluid Dynamics Cfd ◽  
Absolute Frame ◽  
The Relationship

World literature has introduced the aerodynamic importance of unsteadiness in turbines. In particular, the unsteady static pressure field determines the work of the machine. The unsteadiness can redistribute the total pressure in a cascade with wake interaction. It has been shown that differences in work between wake and free stream can act to rectify the wakes and boost efficiency. In this paper, fast response aerodynamic probe (FRAP) data are used to study the nature of the unsteady work in the flow at entry to and exit from a rotating turbine blade. The topic is addressed experimentally, theoretically, and computationally. It is found at both rotor inlet and exit that upstream wakes influence the unsteady work distribution. The relationship between the unsteady work in the absolute frame, the relative frame, and the momentum of the fluid circumferentially is derived and verified experimentally. Computational results (unsteady Reynolds-averaged Navier–Stokes (URANS)) are compared to the experimental results: reasonable agreement is found at rotor exit, but significant differences at rotor inlet are found. The computational fluid dynamics (CFD) has failed to capture the von Karman vortices and has dramatically lower levels of unsteady work. The experimental unsteady work distribution suggests possible effects of wake bending and vortex instability.

Sign in / Sign up

Export Citation Format

Share Document