In Flight Heat Transfer Measurements on an Aero-Engine Nacelle

This paper describes heat transfer measurements on the external surface of a Natural Laminar Flow (NLF) nacelle. The measurement technique employed temperature sensitive liquid crystals and platinum resistance thermometers (PRTs) to measure the surface temperature over an electrically heated pad. This gave an immediate visual indication of the transition location. The heat transfer distribution along the length of the pad has been determined and is compared with a simple theoretical model. Results are presented for the cruise condition of Mach 0.56 at an altitude of 6400m.