In this article, a compound unit of swirl and impingement cooling techniques is designed to study the performance of flow and heat transfer using multi-conical nozzles in a leading-edge of a gas turbine blade. Reynolds Averaged Navier-Stokes equations and the Shear Stress Transport model are numerically solved under different nozzle Reynolds numbers and temperature ratios. Results indicated that the compound cooling unit could achieve a 99.7% increase in heat transfer enhancement by increasing the nozzle Reynolds number from 10,000 to 25,000 at a constant temperature ratio. Also, there is an 11% increase in the overall Nusselt number when the temperature ratio increases from 0.65 to 0.95 at identical nozzle Reynolds number. At 10,000 and 15,000 of nozzle Reynolds numbers, the compound cooling unit achieves 47.9% and 39.8% increases and 63.5% and 66.3% increases in the overall Nusselt number comparing with the available experimental swirl and impingement models, respectively. A correlation for the overall Nusselt number is derived as a function of nozzle Reynolds number and temperature ratio to optimize the results. The current study concluded that the extremely high zones and uniform distribution of heat transfer are perfectly achieved with regard to the characteristics of heat transfer of the compound cooling unit.
Abstract. Casing treatment has been broadly used as a prudent passive flow
control technique to improve the stall margin with a small drop in
efficiency. The effect of grooves in certain details is overlooked however,
different grooves shape (angels and location) has a remarkable effect on the
controlling impact. In the current research work, an investigation on the
effect of fillet and chamfer corners of rectangular circumferential grooves
with various tip gap height on the performance of casing treatment is
carried out with the help of CFD simulation. The performance of different
models of grooves with various tip gap height on NASA rotor 37 is
investigated by discretizing 3D RANS equations based on finite volume
technique. Rectangular circumferential grooves casing treatment (CGCT)
profile and smooth wall casing performances are evaluated. Moreover, the
adiabatic efficiencies and the stall margins of smooth wall casing,
rectangular grooves and rectangular grooves with fillet and chamfer corners
are compared to assess the impacts of profiles of grooves on the stability
and performance of axial flow compressor with different tip gaps. The stall
margin of models 1–6 increased by 4.39 %, 2.52 %,
2.16 %, 1.75 %, 1.69 % and 2.06 % respectively. While the adiabatic
efficiency of the models 1–6 decreased by 0.9 %, 1.01 %,
1.08 %, 1.12 %, 1.22 % and 1.16 % respectively.
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