Thermal characteristics of liquid film in a film regenerative cooling system

Computation method on film regenerative cooling in liquid rocket was studied in this paper.To integrate the factors such as chemistry,evaporation,entrainment,convection,thermal conductivity and radiation,the liquid film was divided into three areas-temperature increase area,evaporation area and steam area to be calculated.Length and thickness of the film were computed,and effects of these factors on film were analyzed.The results show that: (1) Length of liquid film and cooling effectiveness is obviously enhanced with the increase of the film coolant mass flow,and the associated cooling effectiveness is up to 0.57 .(2) Length of liquid film is short in hot combustor,but the cooling effectiveness is up to 0.9 in this area .(3) The film in the head of combustor protects the whole wall even if the liquid has disappeared.Low temperature border area covers the whole combustor .(4) Sensible heat absorbed by the liquid film,evaporation heat of the film and convection heat from hot gas to liquid film are most important elements in liquid film area.However,mass loss and heat transfer caused by entrainment should not be ignored.