Characterization of turbulent jets from high-aspect-ratio rectangular nozzles

Mi, Jianchun; Deo, Ravinesh C.; Nathan, Graham J.

doi:10.1063/1.1928667

Cited by 53 publications

(24 citation statements)

References 13 publications

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“…Importantly, this is associated with no obvious Re-dependent differences in the various statistical properties being observed for Re h Ն 10 000. 54 Next we seek an explanation for why the trends in the influence of Re h in the near-field and far-field rates of spread and decay are opposite. The investigation of Antonia et al 51 ͑and others͒ reveals that the far-field coherent structures are established at a location well downstream from the nominal merging point of the mixing layers but upstream from the onset of self-preservation.…”

Section: -13mentioning

confidence: 99%

The influence of Reynolds number on a plane jet

2008

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The present study systematically investigates through experiments the influence of Reynolds number on a plane jet issuing from a radially contoured, rectangular slot nozzle of large aspect ratio. Detailed velocity measurements were performed for a jet exit Reynolds number spanning the range 1500≤Reh≤16 500, where Reh≡Ubh/υ with Ub as the momentum-averaged exit mean velocity, h as the slot height, and υ as the kinematic viscosity. Additional centerline measurements were also performed for jets from two different nozzles in the same facility to achieve Reh=57 500. All measurements were conducted using single hot-wire anemometry to an axial distance (x) of x≤160h. These measurements revealed a significant dependence of the exit and the downstream flows on Reh despite all exit velocity profiles closely approximating a “top-hat” shape. The effect of Reh on both the mean and turbulent fields is substantial for Reh<10 000 but becomes weaker with increasing Reh. The length of the jet’s potential core, initial primary-vortex shedding frequency, and far-field rates of decay and spread all depend on Reh. The local Reynolds number, Rey0.5≡2Ucy0.5/υ, where Uc and y0.5 are the local centerline velocity and half-width, respectively, are found to scale as Rey0.5∼x1/2. It is also shown that, for Reh≥1500, self-preserving relations of both the turbulence dissipation rate (ε) and smallest scale (η), i.e., ε∼Reh3(x/h)−5/2 and η∼Reh−3/4(x/h)5/8, become valid for x/h≥20.

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Section: -13mentioning

confidence: 99%

The influence of Reynolds number on a plane jet

2008

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“…For a round jet, Haworth and Pope (1987) agreed with the value of 0.086 reported by Wygnanski and Fiedler (1969) and Rodi (1975). Mi et al (2005) showed that, for the plane jet, the centreline decay of the mean velocity is proportional to the streamwise distance to the power minus one-half ( 2 1 − x ), while the half-width varies linearly with the streamwise distance in a region not far downstream from the potential core. For the round jet, on the other hand, the centreline decay of the mean velocity is proportional to the inverse of the streamwise distance ( 1 − x ).…”

Section: Resultsmentioning

confidence: 99%

Comparison of flow and dispersion properties of free and wall turbulent jets for source dynamics characterisation

Aloysius

Wrobel

2009

Environmental Modelling & Software

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The objective of this paper is to provide an investigation, using large eddy simulations, into the dispersion of aircraft jets in co-flowing take-off conditions. Before carrying out such study, simple turbulent plane free and wall jet simulations are carried out to validate the computational models and to assess the impact of the presence of the solid boundary on the flow and dispersion properties.The current study represents a step towards a better understanding of the source dynamics behind an airplane jet engine during the take-off and landing phases. The information provided from these simulations can be used for future improvements of existing dispersion models. Software availabilitySoftware name: FLUENT 6.

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“…The jet centerline defined by the maximum velocity [26,27] is used for a quantification of the intake jet orientation and its velocity profile in direction of flow.…”

Section: Methodology Of Intake Jet Investigationmentioning

confidence: 99%

Investigation of an IC Engine Intake Flow Based on Highly Resolved LES and PIV

Buhl

Hartmann

Kaiser

et al. 2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-To reduce emissions and fuel consumption, the current generation of gasoline engines uses technologies such as direct injection, downsizing and supercharging. All of them require a strong vortical in-cylinder charge motion, usually described as "tumble", to improve fuel-air mixing and enhance flame propagation. The tumble development strongly depends on the flow field during the intake stroke. This flow field is dominated by the intake jet, which has to be captured well in the simulation. This work investigates the intake jet on a steady-state flow bench, especially in the vicinity of the intake valve. At first, the general flow dynamics of the intake jet for three different valve lifts and three different mass flows were investigated experimentally. For the smallest valve lift (3 mm), flow-field measurements using Particle Image Velocimetry (PIV) show that the orientation of the intake jet significantly depends on the air flow rate, attaching to the pent roof for low flow rates. This phenomenon is less pronounced for higher valve lifts. An intermediate valve lift and flow rate were chosen for further investigations by scale-resolving simulations. Three different meshes (coarse, medium and fine) and two turbulence models (Sigma and Detached Eddy Simulation-Shear Stress Transport (DES-SST)) are applied to consider their effect on the numerical results. An ad-hoc postprocessing methodology based on the ensemble-averaged velocity field is presented capturing the jet centerline's mean velocity and velocity fluctuations as well as its orientation, curvature and penetration depth. The simulation results are compared to each other as well as to measurements by PIV.

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Characterization of turbulent jets from high-aspect-ratio rectangular nozzles

Cited by 53 publications

References 13 publications

The influence of Reynolds number on a plane jet

The influence of Reynolds number on a plane jet

Comparison of flow and dispersion properties of free and wall turbulent jets for source dynamics characterisation

Investigation of an IC Engine Intake Flow Based on Highly Resolved LES and PIV

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