Research on the flow characteristics and regulation techniques of ducted fan lip in crosswind conditions
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摘要:
以涵道风扇为动力的飞行器在低速领域中优秀的效率、安全以及噪声特性使其得到重视，如何减小横风条件下唇口的推力损失与进气畸变有待进一步探索。本文采用减小逆压梯度的优化方法对唇口几何进行了优化设计，研究了原始唇口与优化唇口在横风条件下的气动特性及流动规律。为进一步提高唇口的抗横风能力，在优化几何的基础上提出了双唇口结构，并对双唇口结构的流动控制机理进行了分析。结果表明：减小逆压梯度的优化方法可以使唇口在0～0.07的前进比范围内，无量纲推力与总压畸变系数的变化量在3%以内；双唇口结构可以进一步将唇口无量纲推力降低的前进比由0.07提高到0.44；当前进比由0增加到0.55时，采用双唇口结构可以使涵道风扇的总推力降低量由18.5%减小到6.6%。
Abstract:Ducted fan powered aircrafts are valued for their excellent efficiency, safety and noise characteristics in the low-speed field. How to reduce the thrust loss and intake distortion at the lip in crosswind conditions needs to be further explored. In this paper, an optimization method for reducing the adverse pressure gradient was used to optimize the lip geometry. The aerodynamic characteristics and flow laws of the original and optimized lips under crosswind conditions were investigated. In order to further improve the ability of the lip to resist crosswind, a double-lip structure was proposed based on the optimized geometry, and the flow control mechanism of the double-lip structure was analyzed. The results showed that the optimization method of reducing the adverse pressure gradient allowed the lip to vary within 3% of the dimensionless thrust and total pressure distortion coefficient over the advance ratio range of 0 to 0.07. The double-lip configuration allowed a further increase in the advance ratio reduced by the lip dimensionless thrust from 0.07 to 0.44. The total thrust reduction of the ducted fan can be reduced from 18.5% to 6.6% by using the double-mouth structure when the advance ratio increased from 0 to 0.55.
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Key words:
- lip /
- ducted fan /
- crosswind /
- double-lip structure /
- flow control
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图 5 唇口几何参数化及优化后的曲率分布
Figure 5. Geometric parameterization of lip and curvature distribution after optimization
图 7 唇口表面相对压力分布沿周向分布
Figure 7. Relative pressure distribution on lip surface is distributed along the circumference
图 10 唇口出口截面速度分布云图
Figure 10. Velocity distribution cloud diagram of lip outlet section
图 12 唇口表面压力分布随前进比变化
Figure 12. Pressure distribution on lip surface varies with advance ratio
图 14 3种唇口的无量纲推力随前进比变化规律
Figure 14. Non-dimension thrust of three kinds of lips varies with advance ratio
图 15 双唇口结构中截面速度云图
Figure 15. Velocity cloud diagram of cross section in double-lip structure
图 16 3种唇口的总压畸变系数随前进比变化规律
Figure 16. Total pressure distortion coefficient of three kinds of lips varies with advance ratio
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