Effect of Mainstream Velocity on the Optimization of a Fan-Shaped Film-Cooling Hole on a Flat Plate

Lee, Soo In; Jung, Jin Young; Song, Yu; Kwak, Jae Su

doi:10.3390/en14123573

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…Coolant injection from a circular hole improved cooling effectiveness in comparison to that with a square hole, as the enhanced rate of mixing with the hot stream impaired the cooling in the latter case. Optimizing the shape of the injectant hole was shown to have a significant impact on the cooling effectiveness in a recently reported experimental study with flat plate geometry [ 7 ]. Studies by Seban et al [ 8 ] have shown a decrease in film cooling effectiveness due to the angling of the injectors primarily due to accelerated mixing with the mainstream.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Film Cooling Effectiveness in a Supersonic Nozzle

Somasekharan

Srikrishnan

Kumar

et al. 2023

Entropy

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Film cooling as applied to rocket nozzles is analyzed numerically with emphasis on the assessment of the effect of the mixing of coolant with the hot stream. Cooling performance, as characterized by cooling effectiveness, is studied for three different coolants in the three-dimensional, turbulent flow field of a supersonic convergent-divergent nozzle operating with a hot stream temperature of 2500 K over a range of blowing ratios. The coolant stream is injected tangentially into the mainstream using a diffuser-type injector. Parameters influencing the effectiveness, such as coolant injector configuration and mixing layer, are analyzed. Thermal and species mixing between the coolant and the mainstream are investigated with regard to their impact on cooling effectiveness. The results obtained provide insight into the film cooling performance of the gases and the heat transfer characteristics associated with these three gases. An injector taper angle of 30° results in the most effective cooling among the configurations considered (0°, 15°, 30° and 45°). Mixing of the coolant with the hot stream is examined based on the distributions of velocity, temperature and species. The higher values of cooling effectiveness for Helium are attributed to its thermophysical properties and the reduced rate of mixing with the hot stream. The results further indicate that through optimization of the blowing ratio and the coolant injector configuration, the film cooling effectiveness can be substantially improved.

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Section: Introductionmentioning

confidence: 99%

Enhancement of Film Cooling Effectiveness in a Supersonic Nozzle

Somasekharan

Srikrishnan

Kumar

et al. 2023

Entropy

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“…Baek et al [14] performed a numerical study to deeply reveal the inherent flow dynamics of fan-shaped hole film cooling by using the large eddy simulation methodology. Lee et al [15] optimized the fan-shaped hole using experimental methods, wherein the influence of primary flow velocity on the optimization was examined. Based on the fan-shaped holes, many innovative film cooling holes were suggested in recent years (e.g., arrowhead hole [16], NEKOMIMI hole [17], crescent hole [18], dumbbell hole [19], ridge hole [20], tripod hole [21], slot-similar hole [22], etc.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Single-Row Double-Jet Film Cooling of a Turbine Guide Vane under High-Temperature and High-Pressure Conditions

et al. 2022

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Single-row double-jet film cooling (DJFC) of a turbine guide vane is numerically investigated in the present study, under a realistic aero-thermal condition. The double-jet units are positioned at specific locations, with 57% axial chord length (Cx) on the suction side or 28% Cx on the pressure side with respect to the leading edge of the guide vane. Three spanwise spacings (Z) in double-jet unit (Z = 0, 0.5d, and 1.0d, here d is the film hole diameter) and four spanwise injection angles (β = 11°, 17°, 23°, and 29°) are considered in the layout design of double jets. The results show that the layout of double jets affects the coupling of adjacent jets and thus subsequently changes the jet-in-crossflow dynamics. Relative to the spanwise injection angle, the spanwise spacing in a double-jet unit is a more important geometric parameter that affects the jet-in-crossflow dynamics in the downstream flowfield. With the increase in the spanwise injection angle and spanwise spacing in the double-jet unit, the film cooling effectiveness is generally improved. On the suction surface, DJFC does not show any benefit on film cooling improvement under smaller blowing ratios. Only under larger blowing ratios does its positive potential for film cooling enhancement start to show. Compared to the suction surface, the positive potential of the DJFC on enhancing film cooling effectiveness behaves more obviously on the pressure surface. In particular, under large blowing ratios, the DJFC plays dual roles in suppressing jet detachment and broadening the coolant jet spread in a spanwise direction. With regard to the DJFC on the suction surface, its main role in film cooling enhancement relies on the improvement of the spanwise film layer coverage on the film-cooled surface.

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“…Apparently, the mutual interaction between coolant jets and the mainstream can be controlled by altering either the coolant-jet injection or the oncoming mainstream boundary layer flow. Following this acceptance, many passive strategies (such as compound-angle injection [3][4][5], shaped holes [6][7][8][9], shallow trenches [10][11][12], upstream ramps [13][14][15], etc.) for the film cooling enhancement are developed continuously.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on Backward-Injection Film Cooling with Upstream Ramps

et al. 2022

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The present study investigates the effects of upstream ramps on a backward-injection film cooling over a flat surface. Two ramp structures, referred to as a straight-wedge-shaped ramp (SWR) and sand-dune-shaped ramp (SDR), are considered under a series of blowing ratios ranging from M = 0.5 to M = 1.5. Regarding the backward injection, the key mechanism of upstream ramps on film cooling enhancement is suggested to be the enlargement of the horizontal scale of the separate wake vortices and the reduction of their normal dimension. When compared to the SDR, the SWR modifies the backward coolant injection well, such that a larger volume of coolant is suctioned and concentrated in the near-field region at the film-hole trailing edge. As a consequence, the SWR demonstrates a more pronounced enhancement in film cooling than the SDR in the backward-injection process, which is the opposite of the result for the forward-injection scheme. For the SWR, the backward injection provides a better film cooling effectiveness than the forward injection, regardless of blowing ratios. However, for the SDR, the backward injection could show a superior effect to the forward injection on film cooling enhancement, when the blowing ratio is beyond a critical blowing ratio. In the present SDR situation, the critical blowing ratio is identified to be M = 1.0.

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Effect of Mainstream Velocity on the Optimization of a Fan-Shaped Film-Cooling Hole on a Flat Plate

Cited by 6 publications

References 18 publications

Enhancement of Film Cooling Effectiveness in a Supersonic Nozzle

Enhancement of Film Cooling Effectiveness in a Supersonic Nozzle

Numerical Investigation of Single-Row Double-Jet Film Cooling of a Turbine Guide Vane under High-Temperature and High-Pressure Conditions

Numerical Investigation on Backward-Injection Film Cooling with Upstream Ramps

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