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为深入了解超声速连续风洞喷管启动过程中流场结构变化情况,采用数值计算与风洞试验相结合的方法,对连续风洞Ma=4.35喷管进行了研究。分析表明,喷管非定常启动过程可分为“初始蓄气”、“激波串推进”、“核心流推出”、“准稳定增压”四个阶段。其中,“初始蓄气”阶段,气体总压在收缩段不断增加,马赫数在喉道附近逐渐增大;“激波串推进”阶段,激波串结构形成并逐渐向下游推进;“核心流推出”阶段,核心流部分推出边界,但流场结构变化缓慢;“准稳定增压”阶段耗时占整个启动过程耗时的60%以上,且流场结构与稳定阶段流场结构趋于一致,但喷管内各点压力仍不断上升。同时与定常流场对比分析,进一步说明了各阶段流场特点,并指出对“核心流推出”和“准稳定增压”阶段采用定常分析方法的必要性。
In order to gain a better understanding of the structural changes of the flow field during the start-up of a supersonic continuous-flow tunnel nozzle, a numerical simulation and a wind tunnel test were used to study the continuous-flow tunnel Ma = 4.35 nozzle. The analysis shows that the unsteady start-up process of the nozzle can be divided into four stages of “initial gas accumulation”, “shock train propulsion”, “core flow launch” and “quasi-steady pressurization”. Among them, the “initial gas accumulation” stage, the total gas pressure in the shrinking section continues to increase, Mach number gradually increased near the throat; “shock wave string propulsion ” stage, the shock wave structure formed and gradually pushed down ; “Core flow launch” stage, the core flow part of the introduction of the border, but the flow field structure changes slowly; “quasi-steady pressure” phase of the entire start-up process takes more than 60% of the time, and the flow field structure and The structure of the flow field tends to be consistent during the stabilization phase, but the pressure at each point in the nozzle is still rising. At the same time, compared with the steady flow field, the characteristics of the flow field in each stage are further explained, and the necessity of applying the steady analysis method to the “core flow launch” and the “quasi-steady pressurization” stage is pointed out.