Film Cooling Performance of Converging-Slot Holes With Different Exit-Entry Area Ratios

Abstract

Film cooling performances of two kinds of converging slot-hole (console) with different exit-entry area ratios have been measured using a new transient liquid crystal measurement technique which can process the nonuniform initial wall temperature. Four momentum ratios are tested. The film cooling effectiveness distribution features are similar for the two consoles under all the momentum ratios. Consoles with smaller exit-entry area ratio produce higher cooling effectiveness. And the laterally averaged cooling effectiveness results show that the best momentum ratio for both consoles’ film cooling effectiveness distribution is around 2. For both consoles, the heat transfer in the midspan region is stronger than that in the hole centerline region in the upstream, but gradually becomes weaker as flowing downstream. With the momentum ratio increasing, the normalized heat transfer coefficient h/ho of both consoles increases. In the upstream, heat transfer coefficient of console with small exit-entry area ratio is higher. But in the downstream, the jets’ turbulence and the couple vortices play notable elevating effect on the heat transfer coefficient for large exit-entry area ratio case, especially under small momentum ratios. Consoles with smaller exit-entry area ratio provide better thermal protection because of higher cooling effectiveness. And the distributions of heat flux ratio are similar with those of cooling effectiveness because the influence of η on q/q0 is larger. For the consoles, smaller exit-entry area ratios produce lower discharge coefficients when the pressure variation caused by the hole shaped is regarded as flow resistant.

Adiabatic and conjugate cooling effectiveness analysis of a new hybrid scheme

“…The console film hole yielded less aerodynamic loss when compared to the circular and the fan shaped holes, but it showed higher thermal stress concentrations, particularly at the exit area. Liu et al [17] investigated the effect of exit-entry area ratios of 0.67 and 1.33 for console film hole on the film cooling performance. They noted that smaller exit-entry area ratio produced a better thermal protection due to higher film cooling effectiveness with minimum discharge coefficient.…”

Computational prediction into staggered film cooling holes on convex surface of turbine blade

“…The main hot gas velocity and coolant velocity are V g = 59 m/s and V c = 40 m/s respectively while from a previous validation study the temperature ratio was T c /T g =0. 6.…”

“…Liu et al [6] experimentally investigated two kinds of converging slot-holes with different exit-entry area ratios. The experiment was performed on a flat plate using transient liquid crystal measurement technique.…”

Investigation on film cooling characteristics from a row of converging slot-holes on flat plate

“…Detailed flow structures of console film cooling flow field were also investigated by Azzi and Jubran [17] and Yao et al [18] through numerical simulations. Liu et al [19,20] further investigated the effect of console geometry variants including exit-entry area ratio and divergence angle on the film cooling performance of the consoles. The investigations showed that properly changing the geometry parameters of the console could improve the film cooling performance.…”