Mist cooling of very hot tubules with reference to through-hole cooling of gas turbine blades

To develop high temperature gas turbines an advanced cooling method for turbine blades is required. This paper reports an experimental study of mist cooling of very hot tubules using air-water mist flows with particular reference to the through-hole cooling of blades. The experiments were carried out in straight and coiled tubules of 1.8 mm I.D. and local wall temperatures were measured. Firstly, it is ascertained that the heat transfer performance along the tubule axis is divided into three typical regions, namely, liquid film region, dryout region and gas-phase forced convection region. Secondly, it is found that in the liquid film region the heat transfer coefficient is almost ten times higher than that without mist and no instability is observed. Thirdly, the body force gives much different heat transfer performances for the outer and inner sides of the coiled tubule.