超声速连续风洞喷管启动过程分析

Studies on Starting Process of a Continuous Supersonic Wind

关键词:  连续风洞  喷管  启动过程  非定常

Key words:  Continuous wind tunnel  Nozzle  Starting process  Unsteady

摘要:

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。

Abstract:

To further explore the structural changes of flow field during the starting process of a continuous supersonic wind tunnel nozzle，a wind tunnel nozzle with the exit Mach number of 4.35 was investigated numerically and experimentally. The analysis shows that it was not difficult to divide the unsteady starting process of wind tunnel nozzle into four stages，which were named initial accumulation，development of shock train，extrusion of flow，pseudo-stabilization in turn. Thereinto，at the first stage，the pressure in the contraction increased，and the Mach number near the throat rose gradually. At the second stage，a shock train structure was formed and developed. At the third stage，the main flow was beyond the outlet boundary partly. The final stage accounted for more than 60% of the nozzle starting time，and the pressure in the nozzle went up continually，while the flow structure was stable. At the same time，compared with the steady results，this paper further emphasized the characters of each stage，and demonstrated that it is necessary to use the steady result to analyse the starting process at the stage of extrusion of flow，pseudo-stabilization.