Measurements of Secondary Losses in a Turbine Cascade With the Implementation of Nonaxisymmetric Endwall Contouring

Knezevici, D. C.; Sjolander, S. A.; Praisner, T. J.; Allen-Bradley, E.; Grover, E. A.

doi:10.1115/1.3072520

Cited by 50 publications

(24 citation statements)

References 25 publications

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“…2, contained a seven-blade, six-passage linear cascade based on the low-pressure turbine Pack-B airfoil, a generic geometry that has been used [20,[25][26][27][28][29][30][31][32][33][34]. 2, contained a seven-blade, six-passage linear cascade based on the low-pressure turbine Pack-B airfoil, a generic geometry that has been used [20,[25][26][27][28][29][30][31][32][33][34].…”

Section: Experimental Methodsmentioning

confidence: 99%

Overall Effectiveness of a Blade Endwall With Jet Impingement and Film Cooling

Mensch¹,

Thole

2013

Journal of Engineering for Gas Turbines and Power

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Ever-increasing thermal loads on gas turbine components require improved cooling schemes to extend component life. Engine designers often rely on multiple thermal pro-tection techniques, including internal cooling and external film cooling. A conjugate heat transfer model for the endwall of a seven-blade cascade was developed to examine the impact of both convective cooling and solid conduction through the endwall. Appropriate parameters were scaled to ensure engine-relevant temperatures were reported. External film cooling and internal jet impingement cooling were tested separately and together for their combined effects. Experiments with only film cooling showed high effectiveness around film-cooling holes due to convective cooling within the holes. Internal impinge-ment cooling provided more uniform effectiveness than film cooling, and impingement effectiveness improved markedly with increasing blowing ratio. Combining internal impingement and external film cooling produced overall effectiveness values as high as 0.4. A simplified, one-dimensional heat transfer analysis was used to develop a prediction of the combined overall effectiveness using results from impingement only and film cool-ing only cases. The analysis resulted in relatively good predictions, which served to rein-force the consistency of the experimental data. [DOI: 10.1115/1.4025835

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Section: Experimental Methodsmentioning

confidence: 99%

Overall Effectiveness of a Blade Endwall With Jet Impingement and Film Cooling

Mensch¹,

Thole

2013

Journal of Engineering for Gas Turbines and Power

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“…Indeed, the melded corner boundary layer is less rich in kinetic energy and therefore prone to so-called corner separation. This phenomenon is typically found in the junction of the wing and the fuselage of transport aircraft (Levy et al, 2014;Vassberg et al, 2008) or in turbo-machinery cascades (Knezevici et al, 2010). Corner flows are highly influenced by a complex vortex system of primary and secondary vortices and have been investigated in great detail in experimental work addressing the effect of the horseshoe vortex (HSV) near the leading edge (see review paper of Simpson, 2001) and more recently by Gand et al (2015), also focusing on the trailing edge and analyzing the corner vortex.…”

Section: Corner Flow Separation Of Aerodynamically Shaped Junctionsmentioning

confidence: 99%

“…Thereby, the movements of the different components are realized with the overset grid technique (Benek et al, 1986). At the authors' institute, FLOWer is continuously developed to improve simulation capabilities of rotary wings, including high-order schemes (Kowarsch et al, 2013), advanced turbulence modeling (Weihing et al, 2016), fluid structure interaction (Sayed et al, 2016;Klein et al, 2018), wake modeling (Weihing et al, 2017) and optimization for high-performance computing (Letzgus et al, 2018). The code has been extensively validated for wind turbine flows during the MexNext projects, providing accurate predictions of loads and wake measurements (Schepers et al, 2012;Boorsma et al, 2018).…”

Section: Flow Solver and Numerical Settingsmentioning

confidence: 99%

Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

et al. 2018

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Abstract. The present study investigates flow dynamics in the hub region of a wind turbine focusing on the influence of nacelle geometry on the root aerodynamics by means of Reynolds averaged Navier-Stokes simulations with the code FLOWer. The turbine considered is a generic version of the Enercon E44 converter incorporating blades with flat-back-profiled root sections. First, a comparison is drawn between an isolated rotor assumption and a setup including the baseline nacelle geometry in order to elaborate the basic flow features of the blade root. It was found that the nacelle reduces the trailed circulation of the root vortices and improves aerodynamic efficiency for the inner portion of the rotor; on the other hand, it induces a complex vortex system at the juncture to the blade that causes flow separation. The origin of these effects is analyzed in detail. In a second step, the effects of basic geometric parameters describing the nacelle have been analyzed with the purpose of increasing the aerodynamic efficiency in the root region. Therefore, three modification categories have been addressed: the first alters the nacelle diameter, the second varies the blade position relative to the nacelle and the third comprises modifications in the vicinity of the blade-nacelle junction. The impact of the geometrical modifications on the local flow physics are discussed and assessed with respect to aerodynamic performance in the blade root region. It was found that increasing the nacelle diameter deteriorates the root aerodynamics, since the flow separation becomes more pronounced. Possible solutions identified to reduce the flow separation are a shift of the blade in the direction of the rotation or the installation of a fairing fillet in the junction between the blade and the nacelle.

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“…For a turbine cascade, the main objective of endwall contouring is to reduce the secondary losses. This can be done by reducing the strength of the cross-passage flow and retarding the development of the passage vortex (Taremi and Sjolander, 2011;Knezevici et al, 2010;Praisner et al, 2007). For a compressor cascade, in addition to reducing secondary losses, it is also desired to reduce or remove the corner stall, as this is a major source of loss.…”

Section: Endwall Contouringmentioning

confidence: 99%

“…The Pitot tube is installed on the traverse mechanism and is bent such that the tip touches the wall of test section first. Knezevici et al (2010) quotes an uncertainty of ±0.3% of the inlet midspan dynamic pressure for the total pressure readings.…”

Section: Pitot Tubementioning

confidence: 99%

Controlling Secondary Flows in Highly-Loaded Compressor Cascades

Prevost¹

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This thesis documents the experimental results of a research program investigating the effect of non-axisymmetric endwall contouring on the secondary flows and loss generation in a highly-loaded compressor cascade. The results are compared with the losses for the baseline flat endwall in order to evaluate the potential benefits.The compressor blade was designed by Pratt & Whitney Aircraft and is representative of an exit guide vane row in an aircraft engine. The experimental study was conducted in Carleton University's low speed linear cascade wind tunnel. The measurements were made at a constant Reynolds number of 150,000 (based on the axial chord and the inlet velocity) for two values of incidence, 0° (design incidence) and +7°.Quantitative results were obtained from static pressure measurements on the suction and pressure surfaces of the blade to evaluate the blade loadings and from measurements made by a seven-hole pressure probe downstream of the cascade to assess the blade row losses. Qualitative results were obtained from oil surface flow visualisation on the endwall and on the blade surfaces and were used to assist in the interpretation of the flow physics.The current research showed that the application of non-axisymmetric endwall contouring at design incidence modified the secondary flows near the endwall, mitigating the formation of the corner stall. The benefits from contouring were observed in terms of reductions in the secondary losses and in the underturning of the secondary flows compared to the flat endwall test case.However, these benefits were not observed at the off-design incidence studied. The application of endwall contouring generated higher secondary kinetic energy near the endwall, which penetrated deeper along the span and occupied a larger area, resulting in higher secondary and total losses as it dissipated moving downstream of the cascade.iii

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Measurements of Secondary Losses in a Turbine Cascade With the Implementation of Nonaxisymmetric Endwall Contouring

Cited by 50 publications

References 25 publications

Overall Effectiveness of a Blade Endwall With Jet Impingement and Film Cooling

Overall Effectiveness of a Blade Endwall With Jet Impingement and Film Cooling

Numerical analyses and optimizations on the flow in the nacelle region of a wind turbine

Controlling Secondary Flows in Highly-Loaded Compressor Cascades

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