High altitude low Reynolds number effect on the matching performance of a turbofan engine

Under the condition of high altitude and low Mach number, the low Reynolds number greatly affects the performance and aerodynamic stability of aero-engines for high altitude endurance uninhabited aerial vehicles. In order to quantitatively analyze this effect, an iteration simulation method has been employed, in which the aero-engine zero-dimensional simulation is communicated and iterated with the components three-dimensional simulation several turns, until the result is satisfactory. The result shows, under the condition of low Reynolds number, not only the efficiency and the mass flow capacity of the rotational components decline, but also the surge lines of the fan and the compressor move downward. Furthermore, to meet the constraints of different engine components operating together, the matching operation lines of the fan and the compressor move toward the surge line, which leads to the decrease of the surge margin. These simulation results agree well with high altitude experimental results.