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.

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

2011 ◽  
Author(s):  
M. Restemeier ◽  
P. Jeschke ◽  
Y. Guendogdu ◽  
J. Gier
Keyword(s):  
Axial Flow ◽  
Experimental Investigations ◽  
Row Spacing ◽  
Test Rig ◽  
Jet Propulsion ◽  
Turbine Efficiency ◽  
Air Turbine ◽  
Blade Row ◽  
Flow Interactions ◽  
Unsteady Rans

Numerical and experimental investigations have been performed to determine the effect of a variation of the inter blade 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 RWTH Aachen University. The influence of the blade row spacing on aerodynamics has been analyzed by conducting steady and unsteady 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 aero-dynamic improvement of efficiency and favorable spatial distribution of secondary kinetic energy by reduction of the axial gap. It is shown that this relation tends to become less pronounced for multistage turbines.

Time-Resolved Numerical Investigation of the Effects of Blade-Row Spacing on the Turbine Efficiency

2012 ◽  
Author(s):  
S. Behre ◽  
M. Restemeier ◽  
P. Jeschke ◽  
Y. Guendogdu ◽  
K. Engel
Keyword(s):  
Axial Flow ◽  
Suction Side ◽  
Numerical Results ◽  
Row Spacing ◽  
Axial Distance ◽  
Time Resolved ◽  
Turbine Efficiency ◽  
Trailing Edges ◽  
Blade Row ◽  
Unsteady Rans

Numerical investigations of a 1.5 stage axial flow turbine geometry were performed to determine the effects of a variation of the inter-blade row axial gap on turbine efficiency. In order to study the influence of blade row spacing, both steady and unsteady RANS simulations were conducted. State of the art meshing including fillet radii and high grid density was used. In addition to an overall improvement of the aerodynamic efficiency with a decreasing axial distance between the rows, the numerical results showed differences in radial distribution of efficiency downstream of the trailing edges. Furthermore, transition on the blades’ suction side was investigated and compared to former fully turbulent numerical results [1]. The intermittency distributions showed that the laminar fraction of the boundary layer on the rotor, as well as on the second stator suction side, decreases with increasing gap.

Paper 1: Relation between Blade Row Spacing and Potential Flow Interaction Effects in Turbomachines

1969 ◽  
Vol 184 (7) ◽  
pp. 1-8 ◽  
Author(s):  
R. Parker
Keyword(s):  
Potential Flow ◽  
Axial Flow ◽  
Practical Experience ◽  
Interaction Effects ◽  
Row Spacing ◽  
Simple Relationship ◽  
Flow Interaction ◽  
Blade Row ◽  
Flow Interactions ◽  
Flow Compressor

This paper develops a simple relationship between distance upstream and downstream of a row of blades and the velocity disturbances created by the passage of those blades. The relationship is compared with values obtained by numerical computation and measurement in an experimental axial flow compressor rig. The magnitude of vibration exciting forces and/or noise radiation sources due to potential flow interaction on a stationary row of blades is directly related to the magnitude of these velocity fluctuations. The analysis is therefore a basis ( a) for estimating the inter-row spacings for a turbomachine such that potential flow interactions are reduced below the levels of other forms of interaction, and ( b) of translating practical experience of noise and/or vibration excitation in existing machines to give reliable predictions for future designs. It is found that while potential flow interaction effects drop rapidly with increasing blade row spacing for low-speed machines, this is not the case for high speeds and very large spacings may, in fact, be required where the rotor blade speed is equivalent to a high value of Mach number. It is also found that the rate of decrease in effect is related to the circumferential wavelength of the disturbance, and comparisons between machines based on blade chords (as is the present normal practice) are meaningless unless the ratio pitch/chord is constant.

scholarly journals The Computation of Adjacent Blade-Row Effects in a 1.5 Stage Axial Flow Turbine

1997 ◽  
Author(s):  
Rolf Emunds ◽  
Ian K. Jennions ◽  
Dieter Bohn ◽  
Jochen Gier
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Boundary Conditions ◽  
Axial Flow ◽  
The Other ◽  
Navier Stokes ◽  
Blade Row ◽  
Flow Through ◽  
The University

This paper deals with the numerical simulation of flow through a 1.5 stage axial flow turbine. The 3-row configuration has been experimentally investigated at the University of Aachen where measurements behind the first vane, the first stage and the full configuration were taken. These measurements allow single blade row computations, to the measured boundary conditions taken from complete engine experiments, or full multistage simulations. The results are openly available inside the framework of ERCOFTAC 1996. There are two separate but interrelated parts to the paper. Firstly, two significantly different Navier-Stokes codes are used to predict the flow around the first vane and the first rotor, both running in isolation. This is used to engender confidence in the code that is subsequently used to model the multiple bladerow tests, the other code is currently only suitable for a single blade row. Secondly, the 1.5 stage results are compared to the experimental data and promote discussion of surrounding blade row effects on multistage solutions.

scholarly journals Maximizing Multistage Turbine Efficiency by Optimizing Hub and Shroud Shapes and Inlet and Exit Conditions of Each Blade Row

1999 ◽  
Author(s):  
Milan V. Petrovic ◽  
George S. Dulikravich ◽  
Thomas J. Martin
Keyword(s):  
Search Algorithm ◽  
Flow Analysis ◽  
Axial Flow ◽  
Multidisciplinary Optimization ◽  
Design System ◽  
Optimized Design ◽  
Turbine Efficiency ◽  
Through Flow ◽  
Blade Row ◽  
Multistage Turbine

By matching a well established fast through-flow analysis code and an efficient optimization algorithm, a new design system has been developed which optimizes hub and shroud geometry and inlet and exit flow-field parameters for each blade row of a multistage axial flow turbine. The compressible steady state inviscid through-flow code with high fidelity loss and mixing models, based on stream function method and finite element solution procedure, is suitable for fast and accurate flow calculation and performance prediction of multistage axial flow turbines at design and significant off-design conditions. A general-purpose hybrid constrained optimization package has been developed that includes the following modules: genetic algorithm, simulated annealing, modified Nelder-Mead method, sequential quadratic programming, and Davidon-Fletcher-Powell gradient search algorithm. The optimizer performs automatic switching among the modules each time when the local minimum is detected thus offering a robust and versatile tool for constrained multidisciplinary optimization. An analysis of the loss correlations was made to find parameters that have influence on the turbine performance. By varying seventeen variables per each turbine stage it is possible to find an optimal radial distribution of flow parameters at the inlet and outlet of every blade row. Simultaneously, an optimized meridional flow path is found that is defined by the optimized shape of the hub and shroud. The design system has been demonstrated using an example of a single stage transonic axial gas turbine, although the method is directly applicable to multistage turbine optimization. The comparison of computed performance of initial and optimized design shows significant improvement in the turbine efficiency at design and off-design conditions. The entire design optimization process is feasible on a typical single-processor workstation.

Blade Row Interaction in a High-Pressure Steam Turbine

2003 ◽  
Vol 125 (1) ◽  
pp. 14-24 ◽  
Author(s):  
V. S. P. Chaluvadi ◽  
A. I. Kalfas ◽  
H. P. Hodson ◽  
H. Ohyama ◽  
E. Watanabe
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Numerical Simulations ◽  
Steam Turbine ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Flow ◽  
Navier Stokes ◽  
Flow Interaction ◽  
Blade Row

This paper presents a study of the three-dimensional flow field within the blade rows of a high-pressure axial flow steam turbine stage. Compound lean angles have been employed to achieve relatively low blade loading for hub and tip sections and so reduce the secondary losses. The flow field is investigated in a low-speed research turbine using pneumatic and hot-wire probes downstream of the blade row. Steady and unsteady numerical simulations were performed using structured 3-D Navier-Stokes solver to further understand the flow field. Agreement between the simulations and the measurements has been found. The unsteady measurements indicate that there is a significant effect of the stator flow interaction in the downstream rotor blade. The transport of the stator viscous flow through the rotor blade row is described. Unsteady numerical simulations were found to be successful in predicting accurately the flow near the secondary flow interaction regions compared to steady simulations. A method to calculate the unsteady loss generated inside the blade row was developed from the unsteady numerical simulations. The contribution of various regions in the blade to the unsteady loss generation was evaluated. This method can assist the designer in identifying and optimizing the features of the flow that are responsible for the majority of the unsteady loss production. An analytical model was developed to quantify this effect for the vortex transport inside the downstream blade.

Design of a Highly-Loaded Four-Stage Low-Speed Research Compressor

2008 ◽  
Author(s):  
C. Clemen ◽  
H. Schrapp ◽  
V. Gu¨mmer ◽  
R. Mu¨ller ◽  
M. Ku¨nzelmann ◽  
...  
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Flow Measurements ◽  
Low Speed ◽  
Pressure Surface ◽  
Overall Performance ◽  
Inlet Conditions

The present paper describes the design of a new set of blades for the four-stage axial-flow low-speed research compressor (LSRC) at the TU Dresden. The compressor contains nine blade rows: IGV, four rotors and four cantilevered stators designed as repeating stages. The compressor was originally designed and built in the German AG Turbo project. In recent years fourteen builds of the compressor were built and tested [1]. The new design of the NGV (Build A15) has increased pressure ratio and loading compared to the previous builds. The design was performed using a method giving three-dimensionally optimised blades achieving better efficiency than the previous builds with sufficient operating range despite increased loading. The numerical analysis was carried out using a Rolls-Royce 3D-Navier-Stokes solver at design and off-design inlet conditions. The experimental investigations were carried out by the Technical University of Dresden. Overall performance was measured for different speeds and different back-pressures up to compressor stall. Flow field details were measured at a design and a close-to-stall condition using static pressure probes on the blade suction and pressure surface and secondary flow measurements using 5-hole probes.

scholarly journals Theoretical and Experimental Investigation of Circumferential Grooved Casing/Hub Treatment

1994 ◽  
Author(s):  
Zhaohui Du ◽  
Zhiwei Liu
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Experimental Investigations ◽  
Operation Condition ◽  
Stall Margin ◽  
3 Dimensional ◽  
Blade Row ◽  
Stator Blade ◽  
Flow Compressor ◽  
Theoretical Analyses

In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments. A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.

Origins of Loss Within a Multistage Turbine Environment Under Conditions of Partial Admission

1997 ◽  
Author(s):  
Guy R. Wakeley ◽  
Ian Potts
Keyword(s):  
Pressure Ratio ◽  
Axial Flow ◽  
Navier Stokes ◽  
Multi Stage ◽  
Air Turbine ◽  
Partial Admission ◽  
Multistage Turbine ◽  
Bending Stresses ◽  
Swallowing Capacity ◽  
Turbine Design

A partially admitted first stage is routinely used in a wide variety of turbo-machines to match the turbine swallowing capacity to the cycle pressure ratio over a range of outputs. Such a configuration is often favoured for applications in which optimised part-load efficiency is a design requirement. Partial admission is achieved by dividing the stator row into discrete arcs, each of which can be separately supplied with fluid. This arrangement creates circumferential discontinuities and considerable unsteadiness in the flow field within the intra-stage gap, and this unsteadiness can propagate through several downstream rows of fully admitted blading. In the current work an unsteady, multi-stage, multi-passage, Navier-Stokes solver has been validated against experimental results from a multistage axial flow air turbine. Interstage traverses of static and total pressure are shown to agree well with the CFD predictions, and the measured and predicted partial admission loss is compared with published correlations. It is further shown that the operating point of downstream stages is influenced by the degree of partial admission in the first stage. Additionally, increased alternating blade bending stresses are predicted. These phenomena are not included in any published turbine design methods, and are discussed within the context of large output steam turbine optimisation.

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.

Sign in / Sign up

Export Citation Format

Share Document