火箭发动机喷管非定常侧向力和流固耦合研究进展

为了提高现代火箭的运载性能,发动机趋于采用大面积比喷管。然而,大面积比喷管由于低空高背压会产生过膨胀现象,导致喷管内部流动分离的非定常和非对称特性,并且发生显著的侧向载荷问题,巨大的侧向载荷又引起喷管的流固耦合现象。总结了喷管流动分离的研究现状,阐述了不同时期喷管侧向载荷的研究目标及成果,并分析了引起喷管侧向载荷的因素。在侧向载荷分析基础上,进一步分析了喷管流固耦合问题的研究进展及方法,最后指出了所存在的科学问题,剖析了喷管侧向载荷设计的关键力学问题,并对今后喷管侧向力问题的研究方向提出了设想。

ADVANCES IN THE STUDY OF UNSTEADY SIDE-LOADS AND FLUID/STRUCTURE INNTERACTION OF ROCKET NOZZLES

In order to improve the performance of modern rockets, large area-ratio nozzle s are adopted. Over-expansion occurs in large area-ratio nozzles due to high back pressure at low altitudes, leading to unsteady and asymmetrical flow separation inside the nozzle, as well as severe side-loads phenomena. As a result, the large side-loads may lead to remarkable problem of fluid/structure interaction. In this paper, the situation and progress on nozzle flow separation is reviewed. Research object and product of different period were described. Several factors that induce side loads are enumerated, including transition of shock pattern, declining separation line, pressure pulsation, buffeting, fluid/structure coupling, etc. On this basis, progress and research methods on fluid/structure interaction are further analyzed, including experimental and numerical methods. Besides, new research objects that are probably related to side loads are pointed out. Finally,several corresponding critical mechanical problems which need to be considered and settled during large area-ratio nozzle design are discussed, and the suggestion about critical aspects of side-loads needing to be further studied is put forward.