Measurement of local entrainment rate in the initial region of axisymmetric turbulent air jets

Hill, Barry

doi:10.1017/s0022112072001351

Cited by 141 publications

(84 citation statements)

References 1 publication

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“…1 obtained in [23,24] for the turbulent isothermal gas jet is not completely applicable to the highly non-isothermal thermal plasma jet under study, Eq. 1 is still useful for understanding the entrainment of ambient gas into the thermal plasma jet.…”

Section: Resultsmentioning

confidence: 99%

“…The main difference between the turbulent thermal plasma jet encountered in this study and the turbulent isothermal gas jet studied in [23,24] is that the plasma jet has much lower jet-inlet gas density and is not isothermal and thus with temperature-or position-dependent gas properties (density, viscosity, etc.). In comparison with the room-temperature jets studied in [23,24], a flame jet more approximates to the plasma jet.…”

Section: Introductionmentioning

confidence: 88%

“…1) and gas is supplied through the porous-wall and flowing inward into the jet region to act as the entrained gas of the turbulent plasma jet, a pressure difference DP will appear generally between the porous-wall chamber interior and the atmospheric air surroundings outside the cylindrical chamber, depending on the mass flow rate of the supplied gas. If the supplied gas flow rate is larger than that could be entrained by the plasma jet, DP will be[0, while DP\0 will appear when the supplied gas flow rate is less than that required by the jet entrainment [23,24]. Hence, the measured mass flow rate of the gas supplied through the porous-wall when DP = 0 will be equal to the jet entrainment rate.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…1 was found to be 0.32 [23] for the isothermal fully-developed turbulent gas jets with dimensionless axial-length x/d 0 larger than about 13. Using a short porous-wall chamber movable along the axial direction of the turbulent gas jet, Hill measured the local entrainment rate in the initial region of the isothermal turbulent gas jet with dimensionless length x/d 0 smaller than 13 [24]. His experimental results showed that the entrainment coefficient C in Eq.…”

Section: Introductionmentioning

confidence: 99%

“…In comparison with the room-temperature jets studied in [23,24], a flame jet more approximates to the plasma jet. Ref.…”

Section: Introductionmentioning

confidence: 99%

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Direct Measurement of the Gas Entrainment Into a Turbulent Thermal Plasma Jet

Wang

Wei

Meng

et al. 2010

Plasma Chem Plasma Process

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An experimental study is conducted to investigate the entrainment characteristics of a turbulent thermal plasma jet issuing from a DC arc plasma torch operating at atmospheric pressure. The mass flow rate of the ambient gas entrained into the turbulent plasma jet is directly measured by use of the so-called ''porous-wall chamber'' technique. It is shown that a large amount of ambient gas is entrained into the turbulent plasma jet. With the increase of the gas mass flow rate at the plasma jet inlet or the plasma torch exit, the mass flow rate of entrained ambient gas almost linearly increases but its ratio to the jetinlet mass flow rate decreases. The mass flow rate of the entrained gas increases with the increase of the arc current or jet length. It is also found that using different ways to inject the plasma-forming gas into the plasma torch affects the entrainment rate of the turbulent plasma jet. The entrainment rate expression established previously by Ricou and Spalding (J. Fluid Mech. 11: 21, 1961) for the turbulent isothermal jets has been used to correlate the experimental data of the entrainment rates of the turbulent thermal plasma jet, and the entrainment coefficient in the entrainment rate expression is found to be in range from 0.40 to 0.47 for the turbulent thermal plasma jet under study.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In comparison with the room-temperature jets studied in [23,24], a flame jet more approximates to the plasma jet. Ref.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Direct Measurement of the Gas Entrainment Into a Turbulent Thermal Plasma Jet

Wang

Wei

Meng

et al. 2010

Plasma Chem Plasma Process

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Behavior of liquid surface impinged by turbulent jets

Biń

1985

AIChE Journal

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Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient Air

Rabadi

Friedel

Surma³

2007

Chem Eng & Technol

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Two-dimensional phase Doppler anemometer measurements of droplet size and velocity conducted under several nozzle conditions and a systematic variation of the air mass flow quality and liquid phase viscosity show that the air entrainment process is enhanced when keeping all test conditions constant except for increasing the Newtonian liquid viscosity above of that of water. A two-zone entrainment model based on a variable two-phase entrainment coefficient is proposed with the normalized axial distance allowing for a change in the jet angle. Thus, the jet perimeter is lower and the breakup length is longer in the case of air/relatively higher viscosity liquid phase. It provides the most accurate reproduction of the experimental droplet velocity in comparison with that of other models in the literature and, hence, is recommended for the prediction of the droplet velocity in the case of two-phase air/liquid phase free jet flow in stagnant ambient air. A model for predicting the droplet rain out, considering the droplet trajectories in the free jet flow, allows also for an adequate reproduction of the experimental data.

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Measurement of local entrainment rate in the initial region of axisymmetric turbulent air jets

Cited by 141 publications

References 1 publication

Direct Measurement of the Gas Entrainment Into a Turbulent Thermal Plasma Jet

Direct Measurement of the Gas Entrainment Into a Turbulent Thermal Plasma Jet

Behavior of liquid surface impinged by turbulent jets

Prediction of Droplet Velocities and Rain Out in Horizontal Isothermal Free Jet Flows of Air and Viscous Liquid in Stagnant Ambient Air

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