Abstract
Linear stability analysis was carried out for a hydrocarbon liquid fuel jet (n-butane) that was issued into a stagnant gas (nitrogen) whose pressure and temperature exceeded the thermal critical values of the fuel. Within this high pressure / high temperature environment, the liquid fuel jet undergoes sub-to-supercritical transition due to heat addition, changes the method of mass transfer at the gas-liquid interface, and loses surface tension. As a result, we obtained two types of flow instabilities : one is the Rayleigh type and the other is the Taylor type. We numerically calculated the maximum amplification rate of the Rayleigh-type instability, which depends on the square root of the Weber number and the thermodynamic phenomena, such as phase equilibrium and evaporation. Calculation results showed that fluid dynamic and thermal processes are highly coupled ; therefore, the fuel jet instabilities in a supercritical environment are strongly affected by thermodynaamic conditions and physical properties.
