On‐Design and Off‐Design Performance of Variable Area Ejectors: A Comparative Study of Constant Rate of Momentum Change and Constant Rate of Kinetic Energy Change Methods

ABSTRACT The design of the ejector is crucial, as the overall performance and efficiency of the system depend on its internal geometry, dimensions, and flow characteristics. The present experimental study compares the performance of variable area ejectors developed based on the “constant rate of momentum change (CRMC)” and “constant rate of kinetic energy change (CRKEC).” The pressure recovery ratio (PRR) and entrainment ratio ( ω ) at on‐design operating conditions were computed based on experimental results. The study also optimizes both the ejector's entrainment ratio at off‐design conditions and the impact of nozzle exit positions. CRMC ejectors provide higher entrainment ratios (0.512) and lower PRRs (0.178), while CRKEC ejectors provide slightly higher PRRs (0.18) and lower entrainment ratios (0.5) at on‐design conditions. The results indicate that both variable‐area ejectors based on CRMC and CRKEC have their own advantages and limitations regarding performance and suitability for specific applications.