In this article, experiments are carried out in a hypersonic shock tunnel with helium as driver gas and air as the test gas to obtain the convective heating rate and surface pressure distribution on a cone model placed at hypersonic speed. Test is performed in hypersonic shock tunnel for a flow Mach number of 6.5 at two different angles of attack, 0° and 5°. The sputtered thin film platinum sensors are used to measure the heat flux on a cone model. The measured heat-transfer rate compares well with theoretically estimated values using reference enthalpy method and computational fluid dynamics (CFD) simulation. The measured surface pressure compares well with CFD.
Tests were carried in a shock tunnel to determine the heating rate and the wall pressure on a test model flying at hypersonic velocity. The experiments were performed at Mach M = 6.5 and a total enthalpy of 1.2 MJ/kg. Helium was used as the driver gas and air as the driven gas. The effective test time during the tunnel testing was 3.5 ms. The vacuum sputtered gages were used to evaluate the heating rate on the test model. The evaluated heating rate agrees well with numerical simulation. The experimentally measured pressure also agrees with computational fluid dynamics
The heat pipes are passive heat transport devices generally using in electronic cooling. Thermal performance enhancement of heat pipe is essential for better thermal management. The present investigation attempts the effect of thin layer copper coating over the inner surface of the wickless heat pipe (WHP) to improve the heat transfer characteristics and compared with uncoated WHP using R134a, R290 and R600a as working fluids. The influence of fluid fill ratio (in the range between 30% and 80%), at three positions (0°, 45° and 90°) and heat inputs (in the range between 25 and 200 W) on the thermal performance of coated and uncoated WHPs are investigated. Moreover, the significance of Bond, Webber, Kutateladze and condensation numbers on heat transfer performance of coated and uncoated WHPs are investigated. The fill ratio was optimised to 50% (by volume). The results showed that the coated WHP at 45° inclination has improved thermal performance than uncoated WHP. The R600a was identified as a good working fluid because of its favourable thermo-physical properties, which results in low thermal resistance and improved heat transfer coefficients.
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