Heat transfer in valveless Helmholtz pulse combustor straight and elbow tailpipes

A heat transfer correlation is proposed for the pulsating flow in the tailpipe of a valveless Helmholtz pulse combustor. The correlation is developed based on the experimental data of the heat transfer in the straight tailpipe. The constants in the correlation are determined by least-squares fitting of experimental data. The regression model is assessed, and its significance is tested. The correlations of the 45°, 90°, and 135° elbow tailpipes are revised by multiplying factors to that of the straight tailpipe. The maximum error of the correlations is no more than 20%.