Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time

Supersonic vacuum generators, or ejectors, operate pneumatically to extract air from tanks in industrial applications. A key performance metric for ejectors is the Total Evacuation Time (TET), which measures the time required to reach minimum pressure. This research predicts TET using empirical mode...

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Main Authors: Llorenç Macia, Robert Castilla, Gustavo Raush, Pedro Javier Gamez-Montero
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/3/1598
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author Llorenç Macia
Robert Castilla
Gustavo Raush
Pedro Javier Gamez-Montero
author_facet Llorenç Macia
Robert Castilla
Gustavo Raush
Pedro Javier Gamez-Montero
author_sort Llorenç Macia
collection DOAJ
description Supersonic vacuum generators, or ejectors, operate pneumatically to extract air from tanks in industrial applications. A key performance metric for ejectors is the Total Evacuation Time (TET), which measures the time required to reach minimum pressure. This research predicts TET using empirical models that rely on two key metrics: the characteristic curve, which relates absorbed flow rate to the working pressure, and the polytropic curve, which describes the evolution of the polytropic coefficient across working pressures. Accurately capturing both curves for subsequent fitting to polynomial curves is crucial for forecasting TET. Several experimental setups were employed to capture the curves, each of which refined the data and improved the quality of the polynomial fits and coefficients. Multiple setups were necessary to pinpoint the breakpoint, from supersonic to subsonic operation mode, which is a critical factor that affects the characteristic curve and the TET. Furthermore, the research shows an improvement in the TET forecasts for each setup, with deviations between experimental and predicted TET ranging from 7.6% (14.5 s) to a 1.4% (2.6 s) in the most precise setup. Once the models were validated, an optimized ejector design, extracted from an author’s previous article, was tested. It revealed a 4% improvement (8 s) in the TET. These results highlight the importance of the mathematical models developed, which can be used in the future to compare ejectors and reduce the need for experimental data.
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spelling doaj-art-d50b4287b85e4a35a4ec13294e19b16c2025-08-20T02:48:06ZengMDPI AGApplied Sciences2076-34172025-02-01153159810.3390/app15031598Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation TimeLlorenç Macia0Robert Castilla1Gustavo Raush2Pedro Javier Gamez-Montero3CATMech—Centre for Advanced Technologies in Mechanics, Campus Terrassa, Universitat Politecnica de Catalunya, 08222 Terrassa, SpainCATMech—Centre for Advanced Technologies in Mechanics, Campus Terrassa, Universitat Politecnica de Catalunya, 08222 Terrassa, SpainCATMech—Centre for Advanced Technologies in Mechanics, Campus Terrassa, Universitat Politecnica de Catalunya, 08222 Terrassa, SpainDepartment of Fluid Mechanics, Universitat Politecnica de Catalunya, Colom 1, 08222 Terrassa, SpainSupersonic vacuum generators, or ejectors, operate pneumatically to extract air from tanks in industrial applications. A key performance metric for ejectors is the Total Evacuation Time (TET), which measures the time required to reach minimum pressure. This research predicts TET using empirical models that rely on two key metrics: the characteristic curve, which relates absorbed flow rate to the working pressure, and the polytropic curve, which describes the evolution of the polytropic coefficient across working pressures. Accurately capturing both curves for subsequent fitting to polynomial curves is crucial for forecasting TET. Several experimental setups were employed to capture the curves, each of which refined the data and improved the quality of the polynomial fits and coefficients. Multiple setups were necessary to pinpoint the breakpoint, from supersonic to subsonic operation mode, which is a critical factor that affects the characteristic curve and the TET. Furthermore, the research shows an improvement in the TET forecasts for each setup, with deviations between experimental and predicted TET ranging from 7.6% (14.5 s) to a 1.4% (2.6 s) in the most precise setup. Once the models were validated, an optimized ejector design, extracted from an author’s previous article, was tested. It revealed a 4% improvement (8 s) in the TET. These results highlight the importance of the mathematical models developed, which can be used in the future to compare ejectors and reduce the need for experimental data.https://www.mdpi.com/2076-3417/15/3/1598experimental studyvacuum generatorone-stage supersonic ejectorcharacteristic curvepolytropic curveevacuation time
spellingShingle Llorenç Macia
Robert Castilla
Gustavo Raush
Pedro Javier Gamez-Montero
Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
Applied Sciences
experimental study
vacuum generator
one-stage supersonic ejector
characteristic curve
polytropic curve
evacuation time
title Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
title_full Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
title_fullStr Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
title_full_unstemmed Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
title_short Experimental Identification of Characteristic Curves of Supersonic Vacuum Ejector and Empirical Prediction of Total Evacuation Time
title_sort experimental identification of characteristic curves of supersonic vacuum ejector and empirical prediction of total evacuation time
topic experimental study
vacuum generator
one-stage supersonic ejector
characteristic curve
polytropic curve
evacuation time
url https://www.mdpi.com/2076-3417/15/3/1598
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AT gustavoraush experimentalidentificationofcharacteristiccurvesofsupersonicvacuumejectorandempiricalpredictionoftotalevacuationtime
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