进气旋流对推力喷管性影响的研究

介绍了模拟近代大涵道比发动机排气状况的旋流模型,和在喷管落压比1.2到6.5范围内,进气旋流对轴对称喷管,矩形收-扩喷管,楔形二元喷管,和单边膨胀斜板形喷管等性能和射流流态影响等的一些实验结果。实验数据指出:进气旋流可使喷管出口射流柱中的旋涡加强,射流与外界气流间的混合区扩大,中心核心流区缩小,但它对轴对称喷管出口流态的影响很小。进气旋流同时对喷管推力系数和流量系数均起不利影响,增大进气旋流角度会使喷管推力系数和流量都下降,特别是当旋流角超过某一“临界”值后二者降低很急剧,并且二元喷管降低的程度比轴对称喷管更严重,因之在具体应用情况中,保留多大发动机的旋流,要针对具体情况综合考虑各种因素来选定。

AN EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF SWIRLING FLOW ON THE PERFORMANCE OF NOZZLES

The swirl models which were designed to simulate the primary exhaust configuration of current high-bypass ratio engines and some test results of the effects of swirling flow on the performance of axisymmetric nozzle,two-dimensional convergent-divergent nozzle,two-dimensional wedge nozzle,and single expansion ramp nozzle and on the flow pattern of jet at the range of nozzle pressure ratio from 1.2 to 6.5 are presented in this paper.The test data indicate that swirling flow at the nozzle entrance can enhance the intensity of vortices existing in jet plume and hence can increase the mixing zone between plume and external stream and can decrease the central smooth-core flow,but the effect of swirl will be far much smaller for axisymmetric nozzle.Test data also show that this swirling flow may adversely affect nozzle thrust coefficient and discharge coefficient,as swirl angle is increasing both thrust coefficient and discharge coefficient will decrease for each configuration investigated,especially when the swirl angle surpasses a critical value they decrease much faster and it becomes more severe for two-dimensional nozzle than that for axisymmetric one.This critical value of swirl angle depends on nozzle types.Therefore,what degree of engine swirl is in practical application requires a careful analytic considering of all these foctors.