The specific heat ratio of steam in superheat transition zone for critical mass flux calculation

摘要

The traditional method of taking the specific heat ratio of steam as 1.3 in superheat transition zone (0~40K) makes the critical mass flux calculated by the ideal gas method produce an error of up to ±5%. Based on the calculation results of real gas method, this research puts forward a specific heat ratio correction method for steam critical mass flux calculation with ideal gas method. Specific heat ratio in the superheat transition zone is revised with the method and then a regression equation is fitted. By introducing the regression equation to calculation of steam critical mass flux, the error of the result with ideal gas method reduce to ±0.9%, achieving higher accuracy in flow rate calculation of supersonic steam nozzle.