A Low Speed, Transient Facility for Propulsion Heat Transfer Studies

Abstract

A new, low speed, transient heat transfer wind tunnel is evaluated for its ability to provide an accurate and cost effective method to study the effects of convective heat transfer in propulsion related configurations. The facility operates at a constant speed, with either heated or ambient temperature air, and has the capability to rapidly initiate the flow through the test section via a pneumatically controlled dual gate mechanism. A complete description of the facility, in addition to the aerodynamic and thermal transient characteristics, is presented. The aerodynamic testing capabilities of the tunnel were confirmed with measurements in a 90° turning duct that had a radius ratio of 2.3. The measurements include both mean and fluctuating velocities upstream of the bend and at the 90° location. Details of the mean and turbulent primary flow field, the secondary flow field and the complete mean voracity vector are presented. The well documented test case of a cylinder in a cross flow was used to verify the short duration, transient testing technique that is available for the measurement of mean convective heat transfer coefficients. The heat transfer distribution in the stagnation point region of a cylinder in cross flow is presented for the given test condition (free stream velocity fluctuation level and length scale). Comparisons with other experimental and computational heat transfer efforts within the literature and a discussion of the present technique used to estimate the integral length scale of turbulence are presented. The preliminary aerodynamic and heat transfer measurements indicate the transient heat transfer tunnel coupled with the current experimental techniques provides an effective means to study the effects of convective heat transfer in aero propulsion related configurations.