ANALYTICAL STUDY OF LASER-SUPPORTED COMBUSTION WAVES IN HYDROGEN

Laser-supported combustion (LSC) waves are an important ingredient in the fluid mechanics of CW laser propulsion using a hydrogen propellant and 10. 3- mu m lasers. No experimental or analytical information is available on such waves. Therefore, a computer model has been constructued to solve the one-dimensional energy equation with constant pressure and area. Physical processes considered include convection, conduction, absorption of laser energy, radiation energy loss, and accurate properties of equilibrium hydrogen. Calculations for 1, 3, 10, and 30 atm were made for intensities of 10**4 to 10**6 W/cm**2, which gave temperature profiles, wave speed, etc. To pursue the propulsion application, a second computer model was developed to describe the acceleration of the gas emerging from the LSC wave into a variable-pressure converging streamtube, still including all the aforementioned physical processes. One sample calculation was made to the throat. The results show very high temperatures in LSC waves which absorb all the laser energy, and high radiative losses. For the sample accleration case, 42% of the power had been lost by the time the gas arrived at the throat. It appears that heating pure hydrogen with a 10. 6- mu m laser leads to very high temperature ( similar 20,000 K) and large radiative losses.