A detailed method is presented for dotermining the temberature and flow of heated gas necessary for ice prevention of hollow propeller blades in flight and icing conditions. The propeller blade is analytically divided into a number of short radial segments, which are successively treated as separate heat exchangers. Expres¬sions for the total external and internal heat transfer are com¬bined to determine the surface temperatures of each segment. The thermodynamic steady-flow equation is given for the internal gas-flow process and expressions are obtained for the radial variations of gas temperature and pressure within the blade. For a given initial gas temperature in the blade shank cavity, the minimum gas flow is determined, which will provide surface temperatures of at least 32° F everywhere on the heated portion of the blade.nAn expression for the required heat-source input to the gas is included and a formula is given for calculating the required blade-tip nozzle area.nA discussion is included of the indicated benefits to be derived from certain alterations of the blade internal flow passage.
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