Leading Edge Convection Heat Transfer for small UAS

Convection heat transfer is one of the primary phenomena for determining aircraft ice classification and is needed to determine the weight and volume of ice accretion. The flight regime of unmanned aircraft, however, has substantial differences from manned aircraft. Therefore benefit little from their studies on convective heat transfer. A robust study on convective heat transfer for un- manned aerial systems(UAS) would provide a necessary foothold in addressing the icing problem in UAS. The work includes the design and development of a leading-edge convection heat transfer instrument. The instrument is a system of heated wires embedded in a custom built composite wing with a Clark Y airfoil. Initial experiments were conducted to verify sensor functionality and validate the process. The sensor is an assembly of 1/8 inch copper plate, a foil element heater, and thermocouple. Copper was selected as the heat transfer surface due to its high thermal conductivity. It was cut just large enough to accommodate the foil element heater and thermocouple. The heater is 0.3in by 3.5in, and an extra 0.5in was added to allow room for the thermocouple. A narrow sensor is preferred because it requires less modification to match the airfoil profile. For these initial tests, the copper strip is left with square edges, but it will be rounded off in future tests to match airfoil curvature. The results correlate well with previous cylinder experiments and prove a significant deviation from heat transfer functions used in manned aircraft icing models.

Next steps will include flight testing and environmental chamber experimental campaigns. The benefits of conducting a flight campaign were proven by Newton, by addressing the need for accurate levels of free-stream turbulence (Newton). The chamber and flight campaigns are needed to understand icing on low altitude low velocity operations for small UAS and AAM