Heat Transfer Model of a Jet Pump Cowl Anti-Ice System

A theoretical heat transfer model was applied in the design and performance prediction of an aircraft nozzle cowl anti-ice system. Laboratory heat transfer tests were conducted to determine nozzle performance in a curved D-duct specimen. The local convective film coefficient variation on the interior nose cowl surface was empirically fitted relative to the secondary flow parameters in the D-duct. The measured D-duct flow variables were in excellent agreement with the theoretical jet pump model calculations, allowing the model to predict the internal heat transfer coefficient anywhere inside the nose cowl and calculate steady state skin temperature profiles during anti-icing.

By minimizing the predicted thickness of runback ice aft of the heated cowl surface, an optimum nozzle design was determined analytically. The predicted anti-ice performance of the nose cowl ice protection design was later verified by flight test measurements of nose cowl skin temperatures.