Scanned-direct absorption spectroscopy was implemented to improve sensing capabilities in the mixing volume (MV) of the 60 MW Interaction Heating Facility (IHF) at NASA Ames Research Center. The IHF MV conditions range from 5000 to 8000 K and 1 to 9 atm. The path-average line-of-sight measurements of the temperature and enthalpy were inferred using an electronic atomic oxygen transition near 777 nm. A scanned-DAS sensor was optimized to capture high-add-air and high-pressure conditions that previously had not been measurable, including an increased tuning range ($3{\mathrm{cm}}^{-1}$) that allowed for full absorbance profile resolution at maximum pressure test conditions. Enhanced sensor capabilities confirmed uniform flow and flat temperature profiles immediately upstream of the arcjet’s converging–diverging nozzle inlet. Less uniform and parabolic temperature profiles were observed immediately downstream of add-air injection. Time-resolved enthalpy measurements ranged from 16 to 27 MJ/kg and are in agreement with the IHF’s current measurement methods. Centerline measurements along the MV confirmed a reduction in achievable enthalpy after installation of the MV. The centerline measurements quantified the mixing process for various add-air conditions, indicating an opportunity for enthalpy recapture. Axial locations of sufficient mixing were identified and provide a potential for reduction of the MV length and improved facility performance.

实施扫描直接吸收光谱以提高 NASA 艾姆斯研究中心 60 MW 相互作用加热设施 (IHF) 混合体积 (MV) 的传感能力。IHF MV 条件范围为 5000 至 8000 K 和 1 至 9 个大气压。温度和焓的路径平均视线测量值是使用 777 nm 附近的电子原子氧跃迁推断出来的。扫描式 DAS 传感器经过优化，可捕获以前无法测量的高附加空气和高压条件，包括增加的调谐范围（$3{\mathrm{厘米}}^{-1}$) 允许在最大压力测试条件下实现全吸光度分布分辨率。增强的传感器功能证实了电弧喷射会聚-发散喷嘴入口上游的均匀流动和平坦的温度分布。在添加空气注入的下游立即观察到不太均匀和抛物线温度分布。时间分辨焓测量值范围为 16 到 27 MJ/kg，与 IHF 当前的测量方法一致。沿 MV 的中心线测量证实安装 MV 后可实现的焓降低。中心线测量量化了各种添加空气条件下的混合过程，表明有机会重新捕获焓。