基于防失速装置的垫升风机气动性能改善

Aerodynamic Performance Improvement of Axial Flow Lift Fan Based on Anti-Stall Device

针对某气垫船采用的轴流式垫升风机存在马鞍形不稳定区,而风机工作点距离该不稳定区过近,无法满足气垫船在波浪中航行时的垫升流量和压力需求问题,开展防失速装置设计并研究其改善该型风机气动性能的有效性。基于数值仿真和模型试验方法预报该型风机的气动性能,掌握其马鞍形不稳定区产生的内在原因;分析马鞍形不稳定区对气垫船在波浪中的航行性能和垫升风机运行的影响,明确该型风机气动性能的改进方向;根据该型风机内部流体的流动特性开展防失速装置设计,验证其在改善该型风机气动性能方面的有效性,并揭示其抑制马鞍形不稳定区的物理机理。研究表明:叶片上的气流分离是导致该型风机产生马鞍形不稳定区的主要原因;防失速装置能有效抑制动叶和可调前导叶上的气流分离,改善该型风机的内部气流品质,抑制和弱化其马鞍形不稳定区,扩大其稳定工作范围,使其能更好地匹配气垫船在波浪中航行时的垫升流量和压力波动。

Aiming at the problem that the axial flow lift fan applied on a hovercraft has a saddle-shaped unstable region and its working point is too close to this unstable region,causing it unable to meet the lift flow and pressure demands when the hovercraft sails in the waves,the design of anti-stall device and its effectiveness to improve the aerodynamic performance of the lift fan were studied.Firstly,based on the numerical simulation and model test methods,the aerodynamic performance of the lift fan is predicted,and the internal cause of its saddle-shaped unstable region is obtained.Secondly,the influence of saddle-shaped unstable region on the navigation performance of the hovercraft and the operating of the lift fan is analyzed,and the optimization direction of the fan is clarified.Finally,the design of anti-stall device is carried out according to the internal flow characteristics of the fan,and its effectiveness in suppressing the saddle-shaped unstable region of the fan is verified,also its physical mechanism on suppressing the saddle-shaped unstable region of the fan is revealed.The results show that the flow separation of the blades is the main reason for the saddle-shaped unstable region of the lift fan.The anti-stall device can effectively suppress the flow separation of the blades and improve the internal flow quality of the lift fan,hence the saddle-shaped unstable region can be suppressed and weakened.As a result,the stable working region of the lift fan is expanded and it can better match the lift flow and pressure fluctuation when the hovercraft sails in the waves.