Heat Transfer and Flow Characteristics of an Engine Representative Impingement Cooling System

Abstract

A study of a large-scale model of an engine representative impingement cooling system has been performed. A series of tests have been carried out to fully characterise the behaviour of the system. These include cold flow diagnostic tests to determine the pressure loss and the static pressure distribution, and flow visualisation to assess surface shear. The surface shear stress pattern provided by multiple stripes of coloured paint applied to the target surface yielded important information on the near wall flow features far from the jet axis. The row solved flow and pressure distributions are compared to industry standard predictions. Heat transfer tests using the transient liquid crystal technique were also conducted using coatings comprised of a mixture of three thermochromic liquid crystals. Analysis of the thermochromic liquid crystal data was enhanced by recent developments in image processing. In addition, an energy balance approach to analysing signals from fast response thermocouples for air temperature measurement was applied to verify the levels of heat transfer coefficients on surfaces not coated with the temperature sensitive liquid crystal.