New approach to estimate total jet loads with different Knudsen numbers

This short note presents a new approach to estimate coefficients for gaseous jet loads at an inclined flat plate. These load coefficients are derived at the collisionless flow limit. The plate surface can be diffusive or specularly reflective and can have any irregular shapes, but for convenience a rectangular shape was used to demonstrate the work. The coefficients include total pressure, friction, heat flux, moment, and the distances from the pressure force to the plate centers. Direct simulation Monte Carlo simulations are performed to obtain the numerical coefficient results. When the Knudsen (Kn) number is large, those coefficients are close to the exact solutions; when the Kn number is small there are minor deviations. These coefficient formulas can provide quick references for the loads within a wide range of Kn number, and they can significantly reduce or even completely eliminate simulations and measurements.