The Performance of a Generic Non-Axisymmetric End Wall in a Single Stage, Rotating Turbine at On and Off-Design Conditions

Snedden, Glen; Dunn, Dwain; Ingram, Grant; Gregory-Smith, D. G.

doi:10.1115/gt2010-22006

Cited by 16 publications

(14 citation statements)

References 19 publications

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“…Dunn et al (4) found a similar change in the tip leakage flow, but again it could not be explained. The numerical results show that the tip flow was not affected by the contour This is contrary to the numerical work presented in Sneddenet al (15) which uses the same grid and solution settings.…”

Section: Resultscontrasting

confidence: 86%

See 1 more Smart Citation

An unsteady numerical analysis of a generic non-axisymmetric turbine endwall in a 1½ stage turbine test rig

Dunn¹,

Backström²,

Snedden³

2015

Aeronaut.j.

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As concern for the environment increases, so does the desire to reduce emissions and improve fuel efficiency. One avenue being investigated in the aerospace industry is the reduction in losses in a gas turbine engine through endwall contouring, which has shown some promise in improving efficiency. The current investigation was aimed at investigating the unsteady effects downstream of a rotor with a non-axisymmetric endwall contour originally designed for a cascade.Previous investigations (numerical and experimental) have shown that the endwall contour improved the turbine efficiency by reducing the cross passage secondary flows. The contour however had a detrimental effect on the tip flow. The current investigation found that there were negligible unsteady differences between the annular and contoured rotor, with the average comparing well to the steady state results. It was also found that the effects at the tip were due to the experimental blades untwisting during operation.

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Section: Resultscontrasting

confidence: 86%

“…Snedden et al (15) observed that the tip leakage flow was also affected but was not able to comment as to the cause of the change. Dunn et al (4) found a similar change in the tip leakage flow, but again it could not be explained.…”

Section: Resultsmentioning

confidence: 98%

An unsteady numerical analysis of a generic non-axisymmetric turbine endwall in a 1½ stage turbine test rig

Dunn¹,

Backström²,

Snedden³

2015

Aeronaut.j.

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show abstract

“…The reason for large overturning is the high positive incidence at the rotor leading edge. Positive effects of the suppression of overturning at the hub area were mentioned by Snedden et al 6 This explains why the performance of the rotor decreases at low operating conditions. Yasa et al 3 found that with a low rotational speed, the importance of the rotor incidence is higher than the stator exit losses.…”

Section: Stator Flow Fields At Different Operating Conditionsmentioning

confidence: 88%

Performance and flow fields of a supersonic axial turbine at off-design conditions

Grönman

Turunen-Saaresti

Röyttä

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part A:

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The increasing demand of energy efficiency and the utilisation of small-scale energy sources require efficient, small and versatile turbines. Supersonic turbines have a high power density and therefore small size and fewer stages than the subsonic ones. However, the performance of a supersonic turbine can decrease rapidly when operating at off-design conditions. This raises a need for the improvement of the turbine off-design performance. In this article, a supersonic axial flow turbine is studied numerically to find the causes of efficiency decrement. This article presents the most thorough study so far about the reasons that lead to the decreased off-design performance with supersonic axial flow turbines and explains the loss sources individually for the stator and the rotor. Three operating conditions are studied, and it is suggested that at the lower than design pressure ratios, the shock losses of the stator decrease while simultaneously the stator secondary losses increase. The high positive incidence at the lowest modelled pressure ratio, mass flow and rotational speed caused a significant decrease in the rotor and stage performance. This highlights the importance of incidence even in shock-driven supersonic turbine flows.

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“…Five-hole probe measurements followed the methodology of Ingram and Gregory-Smith (25) . Unlike previous results (26,27) , the current investigation was performed with five pressure transducers for the 5-hole probe, as opposed to the four transducers as used previously. This additional transducer allows for a more accurate measurement of the static pressure in sheared flow.…”

Section: Experimental Set Upmentioning

confidence: 99%

On- and off-design performance of a model rotating turbine with non-axisymmetric endwall contouring and a comparison to cascade data

Snedden¹,

Dunn²,

Ingram

2018

Aeronaut. j.

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Non-axisymmetric endwalls in turbine stages have shown to be a robust method to improve the performance of turbines in both power generation and aero-derivative applications. Non-axisymmetric endwalls target the control of secondary flows and are designed using detailed computational fluid dynamics coupled with a variety of optimisation algorithms and utilising a number of objective functions according to the engine company or researcher's preference. These numerical predictions are often backed up by detailed measurements in linear and annular cascades and later proven in full-scale engine tests. Relatively little literature is available describing their performance in rotating test rigs or at conditions other than design, apart from that of the authors. This study comprehensively revisits the low-speed, model turbines used in the earlier study, replacing all of the 5-hole probe data with more accurate results and additional hot-film measurements. These results together with computational fluid dynamics solutions are used to show the success of the method across a large incidence range and to compare to earlier cascade results for a similar endwall and blade profile to establish the usefulness of cascade testing in this application. In addition, a comparison to two other off-design studies is made. Results indicate that the endwalls successfully improve the rotor total isentropic efficiency at all test conditions and that the improvement increases with increased turning in the blade row, from 0.5% to 1.8% across the incidence range. The results also compare well to the estimation of isentropic efficiency improvement that can be drawn from the cascade testing which stands at 1.55%.

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The Performance of a Generic Non-Axisymmetric End Wall in a Single Stage, Rotating Turbine at On and Off-Design Conditions

Cited by 16 publications

References 19 publications

An unsteady numerical analysis of a generic non-axisymmetric turbine endwall in a 1½ stage turbine test rig

An unsteady numerical analysis of a generic non-axisymmetric turbine endwall in a 1½ stage turbine test rig

Performance and flow fields of a supersonic axial turbine at off-design conditions

On- and off-design performance of a model rotating turbine with non-axisymmetric endwall contouring and a comparison to cascade data

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