Experimental and numerical studies on the performance of a precooled supersonic ejector

• Published in: Applied thermal engineering Vol. 253; p. 123823
• Main Authors: Liang, Tao, Li, Zhiyan, Xu, Wanwu, Zhang, Saiqiang, Ye, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.09.2024
• Subjects: Experiment; Mixing layer; Numerical calculation; Precooler; Supersonic ejector; Supersonic ejector; Numerical calculation; Experiment; Precooler; Mixing layer
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2024.123823

•The performance of the novel precooled supersonic ejector is investigated.•The static pressure profile in the flow channel varies with operating conditions.•Precooling the secondary flow increases compression ratio by at least 29%.•The drop in the secondary flow temperature contributes to the mixing process. Precooling the secondary flow enhances the performance of the supersonic ejector. However, reducing the temperature of the secondary flow without experiencing significant pressure loss presents a challenge, particularly when the secondary flow is at high temperature and negative pressure. In response to this challenge, an original design for a two-strut supersonic ejector incorporating a plate-fin precooler is developed. Experimental and numerical calculation methods are employed to analyze the system’s performance under various secondary flow conditions, including ambient air, precooled gas, and non-precooled gas. Moreover, the impact of the secondary flow, including total temperature and mass flow rate on the flow structure and mixing process of the supersonic ejector is analyzed. The results show that the shock waves, reflected shock waves and shock trains exist in the flow channel of supersonic ejector simultaneously. The shock waves intensity decreases with the rise of the total temperature and mass flow rate of the secondary flow. Moreover, this leads to the static pressure behind the nozzle changing from a ω−shape to a U-shape along the flow direction. Meanwhile, the precooler has minimal impact on the pressure loss of the secondary flow while achieving a remarkable pressure recovery coefficient of over 97% and a temperature drops of above 40%. Thus, precooling the secondary flow helps decrease the static pressure in the suction chamber, which results in a minimum 29% increase in compression ratio, enhancing the pumping capacity of supersonic ejector. The study also observed that the drop of secondary flow temperature leads to a lower velocity ratio between the secondary and primary flows, which is beneficial for their mixing process.