横流注入形式对发动机尾喷流红外辐射特性影响的数值研究

Numerical research on infrared radiation characteristics of plume of engine influenced by cross-flow injecting forms

针对轴对称收敛喷管,在其出口设计了横向射流装置,在保持横流总流量相同且进口总温为840K的情况下,数值模拟研究了横流不同注入形式对发动机尾喷流红外辐射的抑制效果.横流的注入能够增强尾喷流与外界气流的掺混,减小高温区长度.结果表明:周向4股注入时的掺混效果要明显弱于横流单股、双股相对注入,故其红外抑制效果也较差;在侧方探测面上,方位角大于20°时,横流单股注入与双股相对注入时的抑制效果非常接近,但后者效果稍好,其最大降幅达到71.6%;在下方探测面,两者的辐射强度均要比其在侧方探测面时大,且双股相对注入时的辐射强度与周向4股注入形式相当;在上方探测面上,相对于其他注入形式,横流单股注入时的辐射强度相对较小,最大降幅达到78.4%.

Numerical study was done under the circumstances of the same total mass flow rate and the total temperature of inlet at 840 K to research the suppression effect of infrared radiation of plume of the engine in different kinds of cross-flow injecting forms. The cross-flow device was designed at the orifice of axisymmetric convergent nozzle. The injection of cross-flow intensified the mixing of plume and outer air flow and thus decreased the length of high-temperature region. It is found that the mixing effect is distinctly worse than single or double oppositely injected when cross-flow is circumferentially injected. At side detection plane, the suppression effect of infrared radiation of single and double opposite injecting comes very close when azimuthal angle is bigger than 20°, but the latter one is slightly better and has a maximum drop of 71.6%. At underneath detection plane, the infrared radiation intensity of single and double opposite injecting is stronger than that at side detection plane, and the latter has a close value when cross-flow is circumferentially injected. At above detection plane, compared with other injecting forms, the infrared radiation intensity of sin gle injecting is relatively weak and reaches a maximum drop of 78.4 %.