Influence of nozzle wall temperature on plate test in arc-heated wind tunnel
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摘要: 为研究电弧风洞喷管壁面温度对平板试验的影响,研制了隔热半椭圆喷管,采用电弧风洞半椭圆喷管平板试验的方法,将喷管长轴边与平板试验模型连接,使气流延伸到模型表面进行试验。喷管扩张段水冷壁面在试验初始时期(冷壁)和壁温上升(热壁)条件下,试验研究了平板测试模型表面冷壁热流和平衡温度的变化。结果表明:在喷管来流焓值1.00~2.55 MJ/kg范围内,相对于冷壁,热壁模型表面冷壁热流增加4.7%~15.0%,平衡温度最大升高4.24%。因此,热防护试验时应考虑喷管壁面温度对平板试验结果带来的影响,需要提高来流焓值。Abstract: In order to study the influence of the nozzle’s wall temperature on the plate test in the arc-heated wind tunnel, a thermal insulation semi-elliptical nozzle was designed. A plate test was adopted in the arc-heated wind tunnel with the semi-elliptical nozzle. The bottom of the nozzle wall was connected with the plate model. The flow extended to the surface of the model during the test. The surface heat flux and equilibrium temperature of the model under the conditions of the hot nozzle wall and the cold nozzle wall were measured and analyzed, respectively. The results show that the enthalpy of the nozzle ranged from 1.00 MJ/kg to 2.55 MJ/kg. Compared with the condition of the cold nozzle wall, the surface heat flux of the hot nozzle wall increased by 4.7% to 15.0%, and the equilibrium temperature increased by up to 4.24%. In the thermal protection test, the influence of the nozzle wall temperature on the results of the plate test should be considered, and it is necessary to increase the enthalpy of the flow.
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Key words:
- arc-heated wind tunnel /
- heat flux /
- enthalpy /
- boundary layer
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表 1 电弧风洞试验状态参数
Table 1. Average values of test parameters in arc-heated wind tunnel
状态 总压/MPa 总焓/(MJ·kg−1) 驻点压力/kPa 驻点热流/(MW·m−2) 气体流量/(kg·s−1) 总功率/MW 1 2.57 1.04 360.76 1.32 6.79 14.53 2 1.98 2.12 277.40 2.86 3.43 15.84 3 1.66 2.55 236.70 3.75 2.45 15.43 表 2 不同总焓及防热板温度下的表面冷壁热流
Table 2. Heat flux on cold wall with different total enthalpies and plate temperatures
状态 时间/s 特征点背温T6/K 测点1热流/(kW·m−2) 测点2热流/(kW·m−2) 测点3热流/(kW·m−2) 10 309.0 182.0 197.0 180.0 1 300 443.0 204.0 224.0 207.0 增量/% 43.4 12.1 13.7 15.0 10 293.0 390.0 370.0 380.0 2 300 1096.0 420.0 420.0 430.0 增量/% 274.1 7.7 13.5 10.5 10 303.0 405.0 418.0 414.0 3 100 1046.0 424.0 456.0 447.0 增量/% 245.2 4.7 9.1 8.0 表 3 近壁面气流总温变化
Table 3. Variation of total air temperature near wall
状态 测点高度/mm 0 5 10 15 1 冷壁温度/K 641 757 873 978 140 s温度/K 714 789 929 985 增量/% 11.4 4.2 6.4 0.7 2 冷壁温度/K 901 1022 1272 1408 140 s温度/K 1058 1214 1359 1459 增量/% 17.4 18.8 6.8 3.6 表 4 隔热平板测温模型平均温度对比
Table 4. Comparison of average temperature on stainless-steel plate
状态 T1/K T2/K Tb1/K Tb2/K 表面温差率/% 背面温差率/% 1 735 723 648 643 0.67 0.78 2 1127 1084 1034 1004 3.89 2.94 3 1249 1201 1109 1063 3.92 4.23 表 5 焓值降低量
Table 5. Decrease of enthalpy
状态 总焓/(MJ·kg−1) 计算恢复焓/(MJ·kg−1) 隔热模型恢复焓/(MJ·kg−1) 近壁气流恢复焓/(MJ·kg−1) 隔热模型焓降/% 近壁气流焓降/% 1 1.04 0.763 0.726 0.76 4.85 0.39 2 2.12 1.216 1.164 1.16 4.28 4.61 3 2.55 1.373 1.306 1.32 4.88 3.86 -
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