Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Ligrani, Phil

doi:10.1155/2012/957421

Cited by 10 publications

(7 citation statements)

References 70 publications

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“…Here subscripts i, e denote values of the total pressure (P o ) at the inlet and outlet evaluation planes, respectively, and the subscript se represents the static pressure at the evaluation plane; total pressure quantities were mass-flow averaged and static pressure quantities were area-averaged using the formulations of Ligrani. 20 It should be noted that the authors regularly observe mass averaged losses at a number of planes throughout the domain as well as mixed-out quantities; however, as to not include an extensive amount of data in the publication we did not include them in this report. However, as a means of transparency we have provided a table comparing the mass averaged losses at the evaluation plane, the mixed-out losses calculated from the evaluation plane and the mass averaged losses at the domain outlet for each airfoil at limit loading Table 2.…”

Section: Resultsmentioning

confidence: 99%

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Effect of inflow conditions on transonic turbine airfoil limit loading

Owen

Taremi

Uddin

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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To better understand airfoil limit loading and the effect inflow conditions have on local efficiency, a computational fluid dynamic investigation was performed for four different transonic turbine airfoils under sub-critical, critical, and supercritical conditions. A computational baseline was established using data previously collected at the Pratt and Whitney Canada High-Speed Wind Tunnel at Carleton University near design conditions using the Reynolds-Averaged Naiver-Stokes shear stress transport k − ω turbulence model with γ transition. The effects of inflow conditions on aerodynamic performance were examined by varying incidence by ± 20°, mainstream turbulence intensity from 5 to 20% and mainstream turbulent length scale from 1 to 100% of the airfoil pitch. Quantitative data of mass-flow averaged Mach numbers, mass-flow averaged flow angles, surface isentropic Mach number distributions and mass-flow averaged total pressure loss coefficients were collected and are presented alongside flow visualizations of numerical Schlieren images to allow for a detailed description of the entire flow domain. Similar to previous experimental work the limit loading pressure ratio and the mass-flow averaged outlet flow angle were strongly correlated with the airfoil outlet metal angle. The influence of inflow conditions was minimal on the exit flow profile with the exception of the mass-flow averaged total pressure loss coefficients. Results show incidence variation to change the total pressure loss coefficient depending on the airfoil, whereas, turbulence intensity and turbulent length scale predicted a drastic increase in loss with increased turbulence level for all airfoils considered.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effect of inflow conditions on transonic turbine airfoil limit loading

Owen

Taremi

Uddin

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…It is well known that a number of methods have been suggested to estimate the aerodynamic loss pertinent to film cooling phenomena, including the methods based on thermodynamic loss, entropy loss, total pressure loss, and so on. Further information about the aerodynamic loss estimation of different film cooling designs can be found in the review paper of Ligrani [36]. In the present study, the aerodynamic loss of the BDSIC design was estimated by using the kinetic energy loss method as suggested by Sargison [37], which is based on the estimation of the aerodynamic penalty of an film cooling design by taking the energy component from the coolant jet flow into the account.…”

Section: The Effects Of the Neighboring Bdsics On The Film Cooling Effectivenessmentioning

confidence: 99%

A novel sand-dune-inspired design for improved film cooling performance

Zhou

2017

International Journal of Heat and Mass Transfer

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An experimental study was performed to explore a novel film cooling design with a Barchan-Dune-Shaped Injection Compound (BDSIC) concept for improved film cooling performance over a test plate. Inspired by the unique crescent-shaped Barchan dunes commonly seen in deserts, the BDSIC concept was proposed to enable coolant streams to be discharged tangentially from hollowed Barchan-dune-shaped (BDS) shells and stay attached to the surface of the test plate. During the experiments, while a highresolution Particle Image Velocimetry (PIV) system was used to conduct detailed flow field measurements to quantify the dynamic mixing process between the coolant stream and the mainstream flows over the test plate, a Pressure Sensitive Paint (PSP) technique was used to map the corresponding adiabatic film cooling effectiveness over the surface of interest based on a mass-flux analog to traditional temperature-based cooling effectiveness measurements.The effects of various important design parameters, including the shape of the BDS shells, the blowing ratio of the coolant streams, and the spanwise distance (i.e., the pitch) between the neighboring BDSICs, on the film cooling performance were evaluated in great detail based the quantitative PSP and PIV measurements. It was found that, in comparison with that of conventional film cooling design with coolant stream injected from circular hole (i.e., the baseline case), the film cooling effectiveness over the test plate would be enhanced significantly (i.e., 30% ~ 500%) by using the BDSIC design, especially for the test case with elongated BDS shells. As expected, the BDSIC design was found to cause a higher aerodynamic loss at relatively low blowing ratios, due to a greater friction loss associated with its complex shape. However, since the unique BDSIC design could keep the coolant stream to stay attached more firmly on the surface of the test plate (i.e., reducing the aerodynamic loss associated with the penetration of the coolant streams into the mainstream flow), the aerodynamic loss of the BDSIC design was found to become even smaller than that of the conventional film cooling design with circular hole design at relatively high blowing ratios. Keywords: Film cooling; Barchan dune inspired film cooling design; Counter rotating vortex structures; PIV measurements, PSP technique; Mass transfer analog in determining film cooling effectiveness; Aerodynamic loss of film cooling design.

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“…There are varieties of methods to calculate the aerodynamic loss, such as using thermodynamic loss, entropy loss, total pressure loss, and so on. Please refer to the review paper by Ligrani 34 for more information. Based on total pressure deficit, Lee et al 35 investigated the aerodynamic loss of compounded film-cooling jet.…”

Section: E Hole Interaction Effect On Film Coolingmentioning

confidence: 99%

An Experimental Study of Barchan-Dune-Shaped Injection Compounds for Improved Film Cooling Effectiveness

Zhou

2016

32nd AIAA Aerodynamic Measurement Technology and Ground Testing Conference

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Inspired by the unique shape of a Barchan dune to prevent sand particles on the ground from being blown away by the oncoming airstream, we proposed a Barchan-duneshaped injection compound (BDSIC) for film cooling. Similar as the sand particles settling down on the ground behind the dune, the coolant streams exhausted from the BDSIC would be able to cover on the surface of interest more widely. The film cooling performance behind the BDSIC had been studied experimentally for a single 35 degree angled hole on a flat plate using the PSP and PIV techniques. The effects of dune shape (shorted, normal, and elongated dune), mass flux ratio (M=0.6, 0.9, 1.2, 1.5), density ratio (DR=0.97, 1.5, 2.1), and hole interaction on the film cooling effectiveness were studied in great detail. It was found that the BDSIC configurations can significantly enhance the film cooling effectiveness of baseline for all test conditions, especially the BDSIC with elongated dune. In addition, the aerodynamic loss study revealed that the turbulent mixings of the BDSIC between jet and mainstream were largely alleviated at relative high mass flux ratios. All in all, the BDSIC concept exhibits the merits from both Barchan dune and ideal tangential slot, demonstrated an enhanced cooling effectiveness with less aerodynamic loss.

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Aerodynamic Losses in Turbines with and without Film Cooling, as Influenced by Mainstream Turbulence, Surface Roughness, Airfoil Shape, and Mach Number

Cited by 10 publications

References 70 publications

Effect of inflow conditions on transonic turbine airfoil limit loading

Effect of inflow conditions on transonic turbine airfoil limit loading

A novel sand-dune-inspired design for improved film cooling performance

An Experimental Study of Barchan-Dune-Shaped Injection Compounds for Improved Film Cooling Effectiveness

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