The Space Heat Flux Calculation Of Spacecraft Based On Reverse Monte Carlo Method

The spacecraft on orbit bears alternated heating and cooling of heat sink from the sun, planets and space, causing fierce change between high and low temperature. Thermal features of spacecraft must be controlled properly so that spacecraft can complete tasks assigned as well as working on space orbits for a long time. Only can we calculate the orbital and suborbital external heat flux accurately and efficiently, the purpose of temperature control can be fulfilled.In order to maintain the advantages of Monte Carlo method when used in radiation heat transfer calculations, and overcome its inefficiency disadvantage when used in getting the radiation flux from big surface to a small surface, the Reverse Monte Carlo Method model was established. The formulas for calculating absorbed earth infrared emission, earth albedo radiation and solar radiation were deduced. The model can not only be used in any kind of earth orbit and aircraft attitude but also can take surface covering and multiple reflection into account conveniently.In this paper, coordinate systems were built at first. The spacecraft coordinate value at any time in inertial frame was gotten according to the Formula Method. The aircraft attitude was determined in term of the given orbit parameters at any time by Continuous Coordinate Transformation Method. Then the absorbed earth infrared emission, earth albedo radiation and solar radiation were computed using RMC method on the constant earth radiation characteristics condition. Compare the heat flux with the results gained by commercial software on the same conditions. It showed that the relative difference of the same kind of heat flux at all test points were less than 3%. It means that the model and the calculating code are correct.In actual fact, the earth emissivity and albedo varies with earth latitude and season, but never a method can take it into consideration when get orbit external heat flux. In this paper, the orbit external heat flux on varying earth radiation characteristics condition was calculated by The RMC method. Compare these results with those gotten on constant earth radiation characteristics condition. The result displayed that earth infrared emission and earth albedo radiation vary considerably, the biggest relative difference of earth infrared emission at all check moments was -21.31%, while the biggest relative difference of the earth albedo radiation was 80.05%. It makes great sense to get the space heat flux in accordance with the actual case to get accurate temperature control.It is always a difficult problem to get the space heat flux when the orbit is transferring, but the RMC model can solve it conveniently. In this paper, the space heat flux of spacecraft orienting earth and the sun on transferring orbit were figured out. The results were correct. The biggest incident solar radiation of the surface which is perpendicular to solar ray is solar constant.