Numerical and Experimental Study of the Performance Effects of Varying Vaneless Space and Vane Solidity in Radial Turbine Stators

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
A. T. Simpson ◽  
S. W. T. Spence ◽  
J. K. Watterson
Keyword(s):  
Numerical Models ◽  
Leading Edge ◽  
Experimental Program ◽  
Cfd Simulations ◽  
Static Pressure Distribution ◽  
Flow Capacity ◽  
Radial Turbine ◽  
Performance Effects ◽  
Stator Vane ◽  
Design Software

An extensive experimental program has been carried out on a 135 mm tip diameter radial turbine using a variety of stator designs, in order to facilitate direct performance comparisons of varying stator vane solidity and the effect of varying the vaneless space. A baseline vaned stator was designed using commercial blade design software, having 15 vanes and a vane trailing edge to rotor leading edge radius ratio (Rte/rle) of 1.13. Two additional series of stator vanes were designed and manufactured; one series having varying vane numbers of 12, 18, 24, and 30, and a further series with Rte/rle ratios of 1.05, 1.175, 1.20, and 1.25. As part of the design process a series of CFD simulations were carried out in order to guide design iterations towards achieving a matched flow capacity for each stator. In this way the variations in the measured stage efficiency could be attributed to the stator passages only, thus allowing direct comparisons to be made. Interstage measurements were taken to capture the static pressure distribution at the rotor inlet and these measurements were then used to validate subsequent numerical models. The overall losses for different stators have been quantified and the variations in the measured and computed efficiency were used to recommend optimum values of vane solidity and Rte/rle.

Numerical and Experimental Study of the Performance Effects of Varying Vaneless Space and Vane Solidity in Radial Inflow Turbine Stators

2008 ◽  
Author(s):  
Alister Simpson ◽  
Stephen Spence ◽  
John Watterson
Keyword(s):  
Numerical Models ◽  
Leading Edge ◽  
Experimental Program ◽  
Cfd Simulations ◽  
Static Pressure Distribution ◽  
Flow Capacity ◽  
Performance Effects ◽  
Stator Vane ◽  
Design Software ◽  
Stage Efficiency

An extensive experimental program has been carried out on a 135 mm tip diameter radial turbine using a variety of stator designs, so as to facilitate direct performance comparisons of varying stator vane solidity and the effect of varying the vane-less space. A baseline nozzle was designed using commercial blade design software, having 15 vanes and a vane trailing edge to rotor leading edge radius ratio (Rte/rle) of 1.13. Two additional sets were designed and manufactured; one set having varying vane numbers of 12, 18, 24 and 30, and a further set with Rte/rle ratios of 1.05, 1.175, 1.20 and 1.25. As part of the design process a series of CFD simulations were carried out in order to guide design iterations towards achieving a matched flow capacity for each stator. In this way the variations in measured stage efficiency could be attributed to the stator passages only, thus allowing direct comparisons to be made. Inter-stage measurements were taken to capture the static pressure distribution at rotor inlet, and these measurements then used to validate subsequent numerical models. The overall losses for different stators have been quantified, and the variations in measured and computed efficiency used to recommend optimum values of vane solidity and Rte/rle.

An Investigation of Turbine Wheelspace Cooling Flow Interactions With a Transonic Hot Gas Path—Part 2: CFD Simulations

2009 ◽  
Author(s):  
G. M. Laskowski ◽  
R. S. Bunker ◽  
J. C. Bailey ◽  
G. Ledezma ◽  
S. Kapetanovic ◽  
...  
Keyword(s):  
Experimental Data ◽  
Leading Edge ◽  
Companion Paper ◽  
Coolant Flow ◽  
Experimental Program ◽  
Cfd Simulations ◽  
Hot Gas ◽  
Pressure Distributions ◽  
Flow Interactions ◽  
Measured Flow

A computational model has been developed to study the mechanisms responsible for hot gas ingestion into the wheel-space cavity of a stationary HPT cascade rig. Simulations were undertaken for the stationary rig described by Bunker et al. (2009) in a companion paper. The rig consists of 5 vanes, a wheel-space cavity and 5 cylinders that represent the blockage due to the leading edge of the rotor airfoils. The experimental program investigated two cylinder diameters and three clocking positions for a nominal coolant flow rate. Comparisons are made between the computed and measured flow-field for the smaller of the two cylinders. It is demonstrated that the circumferential variation of pressure established by the vane wake and leading edge bow wave results in an unstable shear layer over the rim seal axial gap (trench) that causes hot gases to ingest for a nominal coolant flow. Steady state CFD simulations did not capture this effect and it was determined that a unsteady analysis was required in order to match the experimental data. Favorable agreement is noted between the time-averaged computed and measured pressure distributions in the circumferential direction both upstream and downstream of the trench, as well as within the trench itself. Furthermore, it is noted that time-averaged buffer cavity effectiveness agrees to within 5% of the experimental data for the cases studied. The validated CFD model is then used to simulate the effect of rotation by rotating the cylinders and disk at rotational rate that scales with a typical engine. A sliding mesh interface is utilized to communicate data between the stator and rotor domains. The stationary cases tend to ingest past the first angel wing for a nominal coolant flow condition the effect of rotation helps pressurize the cavity and is responsible for preventing hot gas from entering the buffer cavity.

An Investigation of Turbine Wheelspace Cooling Flow Interactions With a Transonic Hot Gas Path—Part II: CFD Simulations

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
G. M. Laskowski ◽  
R. S. Bunker ◽  
J. C. Bailey ◽  
G. Ledezma ◽  
S. Kapetanovic ◽  
...  
Keyword(s):  
Experimental Data ◽  
Leading Edge ◽  
Companion Paper ◽  
Coolant Flow ◽  
Experimental Program ◽  
Cfd Simulations ◽  
Cooling Flow ◽  
Hot Gas ◽  
Flow Interactions ◽  
Measured Flow

A computational model has been developed to study the mechanisms responsible for hot gas ingestion into the wheel-space cavity of a stationary high pressure turbine (HPT) cascade rig. Simulations were undertaken for the stationary rig described by Bunker et al. (2009, “An Investigation of Turbine Wheelspace Cooling Flow Interactions With a Transonic Hot Gas Path—Part I: Experimental Measurements,” ASME Paper No. GT2009-59237) in a companion paper. The rig consists of five vanes, a wheel-space cavity, and five cylinders that represent the blockage due to the leading edge of the rotor airfoils. The experimental program investigated two cylinder diameters and three clocking positions for a nominal coolant flow rate. Comparisons are made between the computed and measured flow-fields for the smaller of the two cylinders. It is demonstrated that the circumferential variation of pressure established by the vane wake and leading edge bow wave results in an unstable shear layer over the rim seal axial gap (trench) that causes hot gases to ingest for a nominal coolant flow. Steady-state computational fluid dynamics (CFD) simulations did not capture this effect and it was determined that an unsteady analysis was required in order to match the experimental data. Favorable agreement is noted between the time-averaged computed and measured pressure distributions in the circumferential direction both upstream and downstream of the trench, as well as within the trench itself. Furthermore, it is noted that time-averaged buffer cavity effectiveness agrees to within 5% of the experimental data for the cases studied. The validated CFD model is then used to simulate the effect of rotation by rotating the cylinders and disk at rotational rate that scales with a typical engine. A sliding mesh interface is utilized to communicate data between the stator and rotor domains. The stationary cases tend to ingest past the first angel-wing for a nominal coolant flow condition, whereas the effect of rotation helps pressurize the cavity and is responsible for preventing hot gas from entering the buffer cavity.

Experimental and Numerical Investigation of Varying Stator Design Parameters for a Radial Turbine

2006 ◽  
Author(s):  
Alister Simpson ◽  
Stephen W. T. Spence ◽  
David W. Artt ◽  
Geoffrey McCullough
Keyword(s):  
Numerical Models ◽  
Incidence Angle ◽  
Experimental Tests ◽  
Turbine Rotor ◽  
Design Parameters ◽  
Radial Turbine ◽  
Stator Vane ◽  
Mass Flow Rates ◽  
Loss Coefficients ◽  
Stage Efficiency

The experimental and numerical investigations of five different vaned stators for a radial turbine are reported. Three different stator vane numbers and three different vane shapes were tested and modelled. The experimental tests were conducted at matched mass flow rates and pressure ratios, using the same 86 mm diameter turbine rotor, allowing direct comparison of the losses arising from each stator configuration. Stator vane number was found to have a small impact on measured stage efficiency (less than 1%), while vane shape was found to have a more significant effect (up to 4%). A commercial CFD code was used to construct a combination of full stage and single passage numerical models of the test turbine. Flow separation as a result of excessive incidence angle at stator inlet was shown to be a significant factor for some of the stators. Predicted pressure loss coefficients for the vaned stators were in the range 7–11%.

scholarly journals Radial Turbine Design for Solar Chimney Power Plants

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 674
Author(s):  
Paul Caicedo ◽  
David Wood ◽  
Craig Johansen
Keyword(s):  
Power Plants ◽  
Reference Frames ◽  
Three Dimensional ◽  
Discrete Ordinates ◽  
Large Area ◽  
Solar Chimney ◽  
Cfd Simulations ◽  
Radial Turbine ◽  
Design Changes ◽  
Turbine Design

Solar chimney power plants (SCPPs) collect air heated over a large area on the ground and exhaust it through a turbine or turbines located near the base of a tall chimney to produce renewable electricity. SCPP design in practice is likely to be specific to the site and of variable size, both of which require a purpose-built turbine. If SCPP turbines cannot be mass produced, unlike wind turbines, for example, they should be as cheap as possible to manufacture as their design changes. It is argued that a radial inflow turbine with blades made from metal sheets, or similar material, is likely to achieve this objective. This turbine type has not previously been considered for SCPPs. This article presents the design of a radial turbine to be placed hypothetically at the bottom of the Manzanares SCPP, the only large prototype to be built. Three-dimensional computational fluid dynamics (CFD) simulations were used to assess the turbine’s performance when installed in the SCPP. Multiple reference frames with the renormalization group k-ε turbulence model, and a discrete ordinates non-gray radiation model were used in the CFD simulations. Three radial turbines were designed and simulated. The largest power output was 77.7 kW at a shaft speed of 15 rpm for a solar radiation of 850 W/m2 which exceeds by more than 40 kW the original axial turbine used in Manzanares. Further, the efficiency of this turbine matches the highest efficiency of competing turbine designs in the literature.

Aerodynamic performance effects due to small leading-edge ice (roughness) on wings and tails

1993 ◽  
Vol 30 (6) ◽  
pp. 807-812 ◽  
Author(s):  
Walter O. Valarezo ◽  
Frank T. Lynch ◽  
Robert J. McGhee
Keyword(s):  
Leading Edge ◽  
Aerodynamic Performance ◽  
Ice Roughness ◽  
Performance Effects

Heat Transfer and Flowfield Measurements in the Leading Edge Region of a Stator Vane Endwall

1999 ◽  
Vol 121 (3) ◽  
pp. 558-568 ◽  
Author(s):  
M. B. Kang ◽  
A. Kohli ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Edge Region ◽  
Leading Edge Vortex ◽  
Stator Vane ◽  
Edge Vortex ◽  
The Mean

The leading edge region of a first-stage stator vane experiences high heat transfer rates, especially near the endwall, making it very important to get a better understanding of the formation of the leading edge vortex. In order to improve numerical predictions of the complex endwall flow, benchmark quality experimental data are required. To this purpose, this study documents the endwall heat transfer and static pressure coefficient distribution of a modern stator vane for two different exit Reynolds numbers (Reex = 6 × 105 and 1.2 × 106). In addition, laser-Doppler velocimeter measurements of all three components of the mean and fluctuating velocities are presented for a plane in the leading edge region. Results indicate that the endwall heat transfer, pressure distribution, and flowfield characteristics change with Reynolds number. The endwall pressure distributions show that lower pressure coefficients occur at higher Reynolds numbers due to secondary flows. The stronger secondary flows cause enhanced heat transfer near the trailing edge of the vane at the higher Reynolds number. On the other hand, the mean velocity, turbulent kinetic energy, and vorticity results indicate that leading edge vortex is stronger and more turbulent at the lower Reynolds number. The Reynolds number also has an effect on the location of the separation point, which moves closer to the stator vane at lower Reynolds numbers.

A Study of Influences of Inlet Total Pressure Distortions On Clearance Flow in an Axial Compressor

2021 ◽  
Author(s):  
Guoming Zhu ◽  
Xiaolan Liu ◽  
Bo Yang ◽  
Moru Song
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Leading Edge ◽  
Stall Margin ◽  
Flow Cells ◽  
Static Pressure Distribution ◽  
Speed Flow ◽  
Clearance Flow ◽  
The Stability

Abstract The rotating distortion generated by upstream wakes or low speed flow cells is a kind of phenomenon in the inlet of middle and rear stages of an axial compressor. Highly complex inflow can obviously affect the performance and the stability of these stages, and is needed to be considered during compressor design. In this paper, a series of unsteady computational fluid dynamics (CFD) simulations is conducted based on a model of an 1-1/2 stage axial compressor to investigate the effects of the distorted inflows near the casing on the compressor performance and the clearance flow. Detailed analysis of the flow field has been performed and interesting results are concluded. The distortions, such as total pressure distortion in circumferential and radial directions, can block the tip region so that the separation loss and the mixing loss in this area are increased, and the efficiency and the total pressure ratio are dropped correspondingly. Besides, the distortions can change the static pressure distribution near the leading edge of the rotor, and make the clearance flow spill out of the rotor edge more easily under near stall condition, especially in the cases with co-rotating distortions. This phenomenon can be used to explain why the stall margin is deteriorated with nonuniform inflows.

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.

Flutter of Supercavitating Hydrofoils-Comparison of Theory and Experiment

1972 ◽  
Vol 16 (03) ◽  
pp. 153-166
Author(s):  
Charles C. S. Song
Keyword(s):  
Leading Edge ◽  
Experimental Program ◽  
Finite Width ◽  
Free Surfaces ◽  
First Order ◽  
Free Jet ◽  
Analytical Work ◽  
Proper Interpretation ◽  
First Order Perturbation ◽  
Good Agreement

Unsteady flow due to harmonic oscillations of a two-dimensional supercavitating flat-plate hydrofoil in a free jet of finite width has been analyzed using first-order perturbation theory. The hydrodynamic loading coefficients thus obtained were used to study the hydroelastic instabilities: flutter and divergence. In conjunction with the analytical work, an experimental program was carried out using a free-jet water tunnel. Special attention was given to the influence of the free surfaces and the point of separation on the critical flutter speed. With proper interpretation of the location of the separation point near the leading edge, the theory and the experimental data were shown to be in fairly good agreement.

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