The impact of a variable-camber inlet guide vane on the performance of a highly loaded counter-rotating fan under variable working conditions

In this research, a variable-camber inlet guide vane (VIGV) is applied to a highly loaded counter-rotating fan for the first time at variable working conditions. Additionally, internal flow analysis of the highly loaded counter-rotating fan is performed to reveal the essential flow mechanism and determine its impact on overall performance. It is found that the through-flow capacity is improved with a decrease in the camber angle. At −10°VIGV, the through-flow capacity increases by 3.1% at the design speed, while the through-flow capacity is only increased by 0.7% at the low corrected speed. The main reason for this is that the through-flow capacity along the blade span of the high-pressure rotor can be increased at the design speed, while only part of the blade span can be increased at the low corrected speed. At the low corrected speed, with the increase in the camber angle, the isentropic efficiency can be effectively improved by the counter-rotating fan, and the isentropic efficiency increases by 1.43% at +20°VIGV. This is mainly due to the decrease in the camber angle reducing the low-pressure rotor's incidence angle along the blade span, which suppresses the flow separation of the low-pressure rotor's suction surface.