单边膨胀矢量喷管气动和红外特性研究

在实验数据验证的基础上,通过计算流体力学/红外辐射(CFD/IR)综合的方法,对不同落压比、不同几何矢量角下的单边膨胀喷管(SERN)进行分析。研究结果表明:喷管无几何矢量动作下,低落压比下的单膨胀边上过度膨胀是造成喷管推力性能急剧下降的原因;喷管在负矢量角下,过度膨胀加剧,推力性能降低;随着喷管几何矢量角绝对值的增加,矢量推力增加,但推力系数减小,喷管几何矢量角在±25°、喷管落压比在3~6的研究范围内,喷管推力系数最低为0.88左右,最高达0.98;喷管几何矢量角为5°时,喷流红外辐射强度最大,喷管矢量角偏离5°的程度越大,尾焰红外辐射强度越低,但是空间分布规律不变。随着喷管几何矢量角的改变,喷管整体红外辐射强度的空间分布规律发生改变,几何矢量角为负时,辐射强度值大的探测角度向下方移动,几何矢量角为正时,喷管整体红外辐射较强的位置分布在上方,由单膨胀边高温壁面以及喷管内腔的可视面积决定。

Research on the Aerodynamic and Infrared Radiation Characteristics of Single Expansion Ramp Vector Nozzle

Based on computational fluid dynamics/infrared radiation(CFD/IR) numerical calculations and validated by experiment,the effect of nozzle pressure ratio and geometry-vector angles of a single expansion ramp nozzle(SERN) on its aerodynamic and infrared radiation characteristics is studied.The results show that when the geometry-vector angle is 0°and the nozzle pressure ratio is low,the aerodynamic characteristic of the nozzle decreases significantly,largely because of over expansion.When the geometry-vector angle is negative,over expansion is more serious and aerodynamic characteristic decreases.With the increase of the absolute value of the geometry-angle,the vector thrust increases,but the thrust coefficient decreases.When the geometry-vector angle is changed from-25° to 25°and the nozzle pressure ratio is changed from 3 to 6,the smallest thrust coefficient is about 0.88 and the biggest thrust coefficient is about 0.98.When the geometry-vector angle is 5°,the infrared radiation of the plume is biggest.When the geometry-vector angle moves away from 5°,the infrared radiation of the plume becomes smaller,but its distribution is not changed.With the variation of the geometry-vector angle,the total infrared radiation of the nozzle presents a different distribution.When the geometry-vector angle is negative,the detecting angle with large infrared radiation is at the underside.When the geometry-vector angle is positive,the upside of the nozzle has large infrared radiation.These are determined by the visible area of the inner wall of the ramp and nozzle lumen.