摘要
高速稀薄等离子体流场在航空航天领域有重要的应用.等离子体射流不同于常规的气体或液体的流动,其内部的电离状态、丰富的反应活性、多样的特征尺度、热平衡与非平衡共存等特点导致传统测速方法难以应用.特征信号图像测速法(SSIV)通过将羽流光强波动作为示踪信号来测量流体速度,从而拥有更好的流体跟随性和测量精度.利用低气压(约为100 Pa)直流电弧等离子体实验平台,文章基于特征信号图像测速方法,通过跟踪发生器输入功率周期变化引起的光强波动来测量纯氩以及氩-氦多组分两种工况下的羽流轴向平均速度分布.将中心波长为696.5 nm的窄带滤光片安装到光学镜头上,进一步获取两种工况下氩原子(ArI)单一谱线所对应的射流速度.结果分析表明,相同工况(电功率、气体质量流量及背景气压)下,氩-氦多组分等离子体的射流平均速度显著高于纯氩等离子体射流的平均速度.并且在氩-氦多组分等离子体的射流中,基于整体光强波动得到的射流速度要明显高于基于Ar I特征谱线获得的速度,表明SSIV方法不仅能够测量可压缩等离子体射流的平均速度,还具有分辨不同组分速度场的能力.研究结果展示了特征信号图像测速方法在复杂流场测量中的适用性和优势.
High-velocity and rarefied plasma flow plays a crucial role in aerospace,especially in thermal protection of high-speed vehicles,optimisation of aerodynamic properties,and plasma control on spacecraft surfaces.Plasma jets are different from conventional gas or liquid flows,and their internal ionisation state,rich reactivity,diverse characteristic scales,and coexistence of thermal equilibrium and nonequilibrium lead to difficulties in applying conventional velocimetry methods.Specific signal image velocimetry(SSIV)measures the fluid velocity by using the plume light intensity fluctuation as a tracer signal,thus possessing better fluid-following and measurement accuracy.Utilizing a lowpressure(~100 Pa)DC arc plasma experimental platform,the article is based on the specific signal image velocimetry method to measure the axial mean velocity distribution of the plume in two working conditions,pure argon as well as argon-helium multicomponent,by tracking the fluctuation of the light intensity caused by the cyclic change of the generator input power.A narrow-band filter with a center wavelength of 696.5 nm was mounted on the optical lens to further obtain the jet velocity corresponding to a single spectral line of argon atoms(Ar I)under the two working conditions.The analysis of the results shows that the average velocity of the jet of the argon-helium multicomponent plasma is significantly higher than that of the pure argon plasma jet under the same working conditions(electric power,gas mass flow rate,and background air pressure).Moreover,in the jet of argon-helium multicomponent plasma,the jet velocity obtained based on the overall light intensity fluctuation is significantly higher than that obtained based on the Ar I eigen-spectra,indicating that the SSIV method is not only capable of measuring the average velocity of compressible plasma jets,but also has the ability to discriminate the velocity fields of different components.The results of the article demonstrate the applicability and superiority of the specific signal image velocimetry method in the measurement of complex flow fields.
作者
张奇志
张晖
曹进文
黄河激
孟显
李腾
耿金越
Zhang Qizhi;Zhang Hui;Cao Jinwen;Huang Heji;Meng Xian;Li Teng;Geng Jinyue(Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China;Guangdong Aerospace Research Academy,Guangzhou 511458,China)
出处
《力学学报》
EI
CAS
CSCD
北大核心
2024年第8期2436-2447,共12页
Chinese Journal of Theoretical and Applied Mechanics
基金
中国科学院A类先导项目(XDA0380600)
国家自然科学基金(12275019)资助。
