Theoretical And Experimental Study On Heat Exchanger Of Laser-Powered Rocket Engine

The Heat exchanger for Laser Propulsion is currently a form of Laser rocket engine,which absorbed laser irradiation energy by the heat exchanger and converted to heat of exhaust propellant.Heat exchanger design had two core issues:First,how to make the shell heat exchanger surface efficiently absorb laser energy;Second,how to strengthen the quality of the heat exchanger between the flow in the microchannel and exhaust propellant.This paper,basesd on the two issues,launched a heat exchanger structural design,heat transfer and fluid flow modeling and analysis of the heat exchanger principle experimental study.First,the paper introduced the concept Laser-Powered Heat exchanger Rocket propulsion and aircraft systems modular.Laser source systems placed in the ground,and used laser beam module array way to achieve high power output;aircraft used the semicircle Columnar,flat bottom fuselage,and the flat bottom surface was heat exchanger Light-heat conversion shell. Advanced laser propulsion system concept aircraft for the output power 10MW of the laser to launch payloads into orbit,estimated the component quality of aircraft,calculated launch trajectory,attained the engine and the heat exchanger performance parameterswith a single output power 1MW,optical Aperture 20m²,the beam-control point precision 10^-6rad.Based on infrared laser absorption theory,a novel Light-heat conversion efficiency of plate heat exchanger shell structure was designed with laser absorption rate of over 85%;established a heat exchanger shell export two-dimensional cross-section temperature field model to analyze the impact for the different propellant,different sizes of micro-channel to heat exchanger surface temperature and the engine exhaust velocity.The results showed,the hydrogen propellant can get higher temperature than nitrogen in the same micro-channel,the smaller size of the micro-channel made difference in temperature smaller,and internal fluid reached a higher temperature.The temperature of using hydrogen propellant,0.2 mm Width of the micro-channel exit can gain higher temperature than using nitrogen propellant,0.4 mm Width,and specific impulse can be reached 620s's.Established one-dimensional flow model of a micro-channel heat exchanger flow and heat transfer,and analyzed the connection of the single micro-channel temperature and velocity of fluid within the laser flux,fluid inlet velocity distribution law.The results show that:with increasing fluid speed of micro-channel,the length of basic micro-channel will shorten and the total heat exchanger area also decrease slightly,but increasing pressure drop with the twice growth rate for velocity of flow.In order to test engine heat exchanger model the feasibility,developing a heat exchanger experimental pieces and experimental systems,made nickel alloy use of heat exchanger shell, with nitrogen propellant,testing the heat exchanger's absorption rate and the 1.06μm and 10.6μm wavelength laser,and analyzed survey data.The results show that metal heat exchanger was higher absorption rate to laser with the short-wavelength laser than long-wavelength,the oxidation of the surface also increases the absorption of laser improve utilization,and the survey data achieved 49%.