No abstract

The William B Morgan Large Cavitation Channel (LCC) is a large variable-pressure closed-loop water tunnel that has been operated by the US Navy in Memphis, TN, USA, since 1991. This facility is well designed for a wide variety of hydrodynamic and hydroacoustic tests. Its overall size and capabilities allow test-model Reynolds numbers to approach, or even achieve, those of full-scale air-or water-borne transportation systems. This paper describes the facility along with some novel implementations of measurement techniques that have been successfully utilized there. In addition, highlights are presented from past test programmes involving (i) cavitation, (ii) near-zero pressure-gradient turbulent boundary layers, (iii) the near-wake flow characteristics of a two-dimensional hydrofoil and (iv) a full-scale research torpedo.

This paper presents an experimental study of the heat transfer on the leading edge of a simulated film cooled turbine airfoil. Previous studies have shown that use of film cooling on the leading edge of an airfoil can significantly increase the heat transfer coefficients around the leading edge which counter-acts the benefits of the adiabatic effectiveness provided by the coolant film. These heat transfer results complement our earlier study of the adiabatic effectiveness for this leading edge and film cooling hole geometry. Heat transfer and adiabatic effectiveness results were combined to determine the overall performance of the film cooling in terms of the net heat flux reduction. Heat transfer coefficients were found to be significantly increased by the film cooling flow in a narrow region which followed the path of the coolant flow. However, heat transfer coefficients were maximum to one side of the coolant jet, consistent with a streamwise vortex flow which is believed to be generated by the interaction of the mainstream with the coolant jet. Overall performance in terms of the net heat flux reduction was found to be unaffected by the large heat transfer coefficients in the vicinity of the holes, but was significantly diminished farther downstream.

An experimental study was conducted to investigate the film cooling performance on the suction side of a first-stage turbine vane. Tests were conducted on a nine times scale vane model at density ratios of DR=1.1 and 1.6 over a range of blowing conditions, 0.2⩽M⩽1.5 and 0.05⩽I⩽1.2. Two different mainstream turbulence intensity levels, Tu∞=0.5 and 20 percent, were also investigated. The row of coolant holes studied was located in a position of both strong curvature and strong favorable pressure gradient. In addition, its performance was isolated by blocking the leading edge showerhead coolant holes. Adiabatic effectiveness measurements were made using an infrared camera to map the surface temperature distribution. The results indicate that film cooling performance was greatly enhanced over holes with a similar 50 deg injection angle on a flat plate. Overall, adiabatic effectiveness scaled with mass flux ratio for low blowing conditions and with momentum flux ratio for high blowing conditions. However, for M<0.5, there was a higher rate of decay for the low density ratio data. High mainstream turbulence had little effect at low blowing ratios, but degraded performance at higher blowing ratios.

Film cooling performance was studied on a simulated turbine vane model with an objective of determining how much the coolant density ratio affects this performance. Experiments were conducted using coolant density ratios of 1.8 and 1.2. The purpose of the study was to determine if tests done at small density ratios (which is often more viable in a laboratory) can give reasonable predictions of performance at more realistic large density ratios. Furthermore, appropriate scaling parameters were determined. The mainstream flow was operated with low and high turbulence levels. Adiabatic effectiveness was measured in the showerhead region of the vane, and following the first row of coolant holes on the pressure side. Adiabatic effectiveness performance using small density ratio coolant gave performance trends similar to the large density ratio coolant, but quantitative values differed by varying amount depending on operating conditions.