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<p>Ejectors are extensively used in various industries for their simple design, low maintenance, and cost efficiency. This study studies existing one-dimensional (1D) theoretical models and introduces a novel 1D model addressing their shortcomings. Using computational fluid dynamics (CFD), we demonstrate inaccuracies in traditional models, particularly regarding the momentum equation and over-expansion theory of the primary nozzle's flow, which blocks the secondary flow. For the ejector used in this study, we calculated the mixed flow velocity at different planes in the constant-area section using CFD and compared it with traditional 1D models. Our novel 1D model, designed for double-choked operating conditions, accurately predicts the critical back pressure, closely matching CFD results. It avoids the inaccuracies of traditional models by not using the momentum equation and ensures sonic velocity in the constant-area section, minimizing losses due to normal shocks and improving efficiency. The proposed model was validated by designing an ejector for specified boundary conditions and confirming its accuracy through CFD simulations. In CFD simulations, the measured critical back pressure of 88&#xa0;kPa was acceptably close to the predicted values from our 1D model (93&#xa0;kPa).</p>

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A novel 1D model for the analysis of double-choked ejectors validated by CFD simulations

  • 期刊论文

  • 发表日期：

    2025年4月21日

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  • Saeed Akbarnejad,
  • Masoud Ziabasharhagh

摘要

Ejectors are extensively used in various industries for their simple design, low maintenance, and cost efficiency. This study studies existing one-dimensional (1D) theoretical models and introduces a novel 1D model addressing their shortcomings. Using computational fluid dynamics (CFD), we demonstrate inaccuracies in traditional models, particularly regarding the momentum equation and over-expansion theory of the primary nozzle's flow, which blocks the secondary flow. For the ejector used in this study, we calculated the mixed flow velocity at different planes in the constant-area section using CFD and compared it with traditional 1D models. Our novel 1D model, designed for double-choked operating conditions, accurately predicts the critical back pressure, closely matching CFD results. It avoids the inaccuracies of traditional models by not using the momentum equation and ensures sonic velocity in the constant-area section, minimizing losses due to normal shocks and improving efficiency. The proposed model was validated by designing an ejector for specified boundary conditions and confirming its accuracy through CFD simulations. In CFD simulations, the measured critical back pressure of 88 kPa was acceptably close to the predicted values from our 1D model (93 kPa).