Estimation of the local convective heat transfer coefficients of low frequency two-phase pulsating impingement jets using the IHCP

ABSTRACT In this paper, a numerical-experimental investigation was performed for estimation of the local convective heat transfer coefficients of a two-phase pulsating heated jet impinging a cold disk-shaped mass. By solving the energy equation, temperature history of thermocouples was obtained and then using the “temperatures measured” at locations of the sensors and the “temperatures calculated” from the numerical solution of heat equation and then minimizing the sum of squared errors by the conjugate gradient method (CGM), the convective heat transfer coefficients are estimated using the nonlinear inverse heat conduction procedure (IHCP). To compare the heat transfer characteristics of the pulsating, steady, bubbly, and liquid-only jets, the heat transfer coefficients were estimated with respect to the square pulse frequency produced by a solenoid valve in the range of and the gas volume fraction in the range of . In the case of single-phase jet, results show that flow pulsation increases Nusselt number up to at the stagnation point and for farther radial distances as compared to the steady jet. Also, for steady jet, increasing Reynolds number resulted in a increase in the stagnation point Nusselt number and a increase at farther radial distances.