Investigation of Calculation Methods for Convective Heat Transfer Coefficient in Combustion Chambers and in Converging-Diverging Nozzles

This paper reports a review and comparison of the methods used for calculating convective heat transfer coefficient in combustion chambers and in diverging-converging nozzles. Therefore, a history of applying different methods for calculating the convective heat transfer coefficient is explained first. Then, the nozzle flow is numerically solved, using the explicit McCormack method. In a Bates nozzle, The methods of Bartz, Stanton, Preiskorn, and Adami were selected among the proposed methods and were compared with CFD. Convective heat transfer coefficient of a solid fuel engine was calculated by taking into account the flow parameters in the engine chamber. Consequently, it was found that as wet move to the nozzle, heat transfer coefficient increases with velocity of the flow. This results revealed that in analytical methods, the maximum convective heat transfer coefficient occurs in the nozzle throat, while CFD results show that the maximum occurs upstream of the nozzle throat. These methods require less computational time than CFD, however CFD has to be considered more accurately. As a result, during a preliminary design procedure, the much faster and slightly less precise method can be used, in particular at the throat where the relative difference between the methods is quite low. Finally, it was shown that the innovative approach of combining Adami and Bartz methods has the lowest possible error, compared to the CFD.