COOLING OF RAM JETS AND TALL-PIPE BURNERS – ANALYTICAL METHOD FOR DETERMINING TEMPERATURES OF COMBUSTION CHAMBER HAVING ANNULAR COOLING PASSAGE

摘要

An analytical method is given for calculating the maximum wall temperature of a tail-pipe burner or a ram-jet combustion chamber cooled by air or gas flowing through a surrounding annular passage. Data from step-by-step integrations of the heat flow from the com¬bustion gas to the cooling gas, which take into consideration the longitudinal temperature distribution of the combustion gases, the variation of heat-transfer coefficients along the burner length, and radiation from combustion gases to the combustion-chamber wall, are used to develop an empirical equation expressing the outlet temperature of the cooling gas in terms of known conditions of flow and geometry. When the outlet cooling-gas temperature is known, two parameters can be- evaluated that make possible the determina¬tion of the maximum temperature of the inside wall from a working chart, which is a solution of the heat balance across the inside wall at the outlet„nExtensive combinations and ranges of the independent variables (mass velocity of combustion gas, mass velocity of cooling gas, inlet cooling-air temperature, final combustion-gas temperature, burner diameter, cooling-passage height, burner length, and fins) have been generalized by the empirical equation, which greatly reduces the labor of calculating the inside-wall temperature.