Effect of Solidity and Camber Angle on Performance in Contra-rotating Open Rotor Design

In this paper, an aerodynamic design method for a contra-rotating open rotor based on lifting line theory is presented. By changing the number of blades, the solidity and camber angle are changed, and several different aerodynamic designs are completed. The effect of solidity and camber angle on the aerodynamic performance is studied. The results show that when the number of blades increases, the solidity linearly increases while the camber angle nonlinearly decreases. There exists an optimal number of blades for aerodynamic design. The highest propulsion efficiency improved by 2.41% compared to the lowest value. The highest propulsion efficiency of 0.81 occurred with 10 blades. Increased solidity leads to increased viscous and wake losses. The change in solidity also changes the shock wave structure in the channel and the static pressure distribution on the blade surface. When the number of blades is reduced, decreased solidity results in greater circumferential differential pressure. The increased camber angle brings a larger inverse pressure gradient in the flow direction. This resulted in a significant flow reversal region in the channel, increasing the rear rotor root losses.