Mist/steam heat transfer of multiple rows of impinging jets

Internal mist/steam blade cooling technology is considered for future high-temperature gas turbine systems that burn hydrogen or synthetic gases. This paper experimentally investigates the mist/steam heat transfer of three rows of circular jet impingement in a confined channel. Experiments were conducted with Reynolds numbers at 7500 and 15,000 and heat fluxes ranging from 3350 to 13,400 W/m2. The results indicate that the wall temperature significantly decreased because of mist injection. The cooling enhancement region of the three-row jet impingement jets is more extensive than those employing one row of circular jets or a slot jet. The highest enhanced region spans about five jet diameters and becomes negligible downstream. The maximum local enhancement is up to 800% by injecting 3.5% of mist at low heat flux condition and 150% at high heat flux condition. The average cooling enhancement can achieve more than 100% within two jet-diameter distance from the stagnation line at Re = 15,000 and ml/ms = 1.5%.