Experimental investigation on thermo-acoustic instability and heat transfer of supercritical endothermic hydrocarbon fuel in a mini tube

The thermo-acoustic instability and heat transfer coefficients of a kerosene kind endothermic hydrocarbon fuel were experimentally investigated in a horizontal mini tube at supercritical pressure. The test section was a 316 stainless steel tube with a length of 240 mm and an inner diameter of 1.60 mm. Experiments were conducted at pressures of 2.5-4.0 MPa, mass fluxes of 800-1200 kg/m2·s, and heat fluxes of 665-950 kW/m2. The relative standard deviation (RSD) of pressure drop was used to evaluate the intensity of thermo-acoustic instability. The correlation between heat transfer coefficient and the oscillation intensity was discussed. The results indicate that the periodic decrease in wall temperature is accompanied by synchronous increases in the outlet bulk temperature and pressure drop during oscillation. Thermo-acoustic oscillation is more pronounced at lower mass flux, lower pressure, or higher heat flux. The instability disappears when the inlet bulk temperature exceeds a threshold value. In the oscillation region, the heat transfer coefficient is positively correlated with the oscillation intensity. Heat transfer deterioration will occur at the stable boundary between the oscillation region and the stable region. A dimensionless criterion is obtained to evaluate the stable boundary of thermal-acoustic oscillation.