Heat Transfer Characteristics of an Integrated Cooling Configuration for Ultra-High Temperature Turbine Blades: Experimental and Numerical Investigations

Abstract

This paper deals with fundamental research on heat transfer characteristics inside a cooling configuration designed for an ultra-high temperature turbine nozzle. The cooling configuration adopted in this study integrates impingement cooling and pin cooling devices into one body, aiming at the enhancement of the effective area for the impingement cooling. A large-scaled test model of this cooling system is constructed to measure its internal heat transfer distribution, where a number of pins are sandwiched between an impingement plate and a target plate. The target plate are provided with several air discharging holes. A focus of this study is on how the heat transfer characteristics depend on the effect of stand-off distance: a distance between these two plates. Ratios of the stand-off distance to the impingement hole diameter varies from 0.75 to 2.00. A transient measurement technique using narrow-banded thermochromatic liquid crystal (TLC) is employed to determine the heat transfer characteristics of the model. Numerical investigations using a commercial CFD code are also executed and those results are compared with the experimental data. It is accordingly found that the numerical results almost match the measurements. It is also shown that the addition of pins to the conventional impingement cooling system can produce about 50% increase in the effective cooling area.

Systematic Numerical Studies on Heat Transfer and Aerodynamic Characteristics of Impingement Cooling Devices Combined With Pins

“…Uniform velocity distribution ( U in ) was assumed over the inlet plane. The previous study by Funazaki et al [2] examined the validity of this assumption, reaching a conclusion that the uniform inlet velocity distribution was an acceptable assumption, at least in their test case. Inlet turbulence kinetic energy was set to be 0.01U in 2 and initial dissipation rate was k d in 2 0 05 .…”

“…One jobs usually converged in about 24 cpu hours. Figure 4 exhibits comparisons between the experimental heat transfer obtained for the cooling device configuration of Case 1 and H d = 1 [2][3] and its numerical counterparts calculated using the abovementioned five turbulence models. Note that uncertainty of the experimental data was estimated to be about 6% [2].…”

“…Figure 4 exhibits comparisons between the experimental heat transfer obtained for the cooling device configuration of Case 1 and H d = 1 [2][3] and its numerical counterparts calculated using the abovementioned five turbulence models. Note that uncertainty of the experimental data was estimated to be about 6% [2]. The Nusselt number on the target plate and the pin, irrespective of experiment or calculation, were separately averaged to have averaged heat transfer coefficients denoted as T.P.…”

“…To meet this goal, the present authors have been investigating heat transfer characteristics of a cooling device that combines impingement cooling with pin-fin cooling as shown in Figure 1 (Funazaki et al. [1] [2]). In this case the pins were employed not only to disturb the impingement jets on target plate so as to enhance the turbulence in the flow but also to increase the internal surface area.…”

Numerical predictions of jet impingement heat transfer on square pin-fin roughened plates

“…Quan et al [10] measured the cooling performance of an impingement system combined with pin fins by using infrared technology, and the overall cooling effectiveness was above 0.8. Funazaki et al [11,12], Son, et al [9] and Yamawaki et al [13] investigated the impingement cooling combined with circular pin fins by using transient liquid crystal technology. Their results showed that the wetted-area averaged Nusselt number of pin-fin roughened target plate was lower than flat plate; however the total heat transfer quantity of the pin-fin roughened plate increased by up to 50%, and the maximum pressure loss only increased by 10%.…”