Simultaneous measurements of temperature and velocity fluctuations in a slightly heated jet combining a cold wire and Laser Doppler Anemometry

Piétri, Laurence; Amielh, Muriel; Anselmet, Fabien

doi:10.1016/s0142-727x(99)00071-5

Cited by 42 publications

(17 citation statements)

References 26 publications

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“…One traditionnal method consists in setting up velocity measurement and temperature measurement, independantly of each other, e.g. fast cold wires combined with either Laser-Doppler-Anemometry [21], or Particle-Image-Velocimetry [22]. However, achieving accurate synchronisation and ensuring that the measurement points precisely match is not straightforward.…”

Section: Turbulent Scalar Dynamicsmentioning

confidence: 99%

A local sensor for joint temperature and velocity measurements in turbulent flows

Salort

Rusaouen

Robert

et al. 2018

Review of Scientific Instruments

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We present the principle for a micro-sensor aimed at measuring local correlations of turbulent velocity and temperature. The operating principle is versatile and can be adapted for various types of flow. It is based on a micro-machined cantilever, on the tip of which a platinum resistor is patterned. The deflection of the cantilever yields an estimate for the local velocity, and the impedance of the platinum yields an estimate for the local temperature. The velocity measurement is tested in two turbulent jets: one with air at room temperature which allows us to compare with well-known calibrated reference anemometers, and another one in the GReC jet at CERN with cryogenic gaseous helium which allows a much larger range of resolved turbulent scales. The recording of temperature fluctuations is tested in the Barrel of Ilmenau which provides a controlled turbulent thermal flow in air. Measurements in the wake of a heated or cooled cylinder demonstrate the capability of the sensor to display the cross correlation between temperature and velocity correctly.

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Section: Turbulent Scalar Dynamicsmentioning

confidence: 99%

A local sensor for joint temperature and velocity measurements in turbulent flows

Salort

Rusaouen

Robert

et al. 2018

Review of Scientific Instruments

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“…Experiments and direct simulations indicate that the turbulent Schmidt number Sc T and the turbulent Prandtl number Pr T in jets and plumes, respectively, are less than one (see e.g. Chen & Rodi 1980;Pietri et al 2000;Wang & Law 2002;Ezzamel et al 2015;van Reeuwijk et al 2016, and the experimental data in table 1). For jets it is well established that the observation Sc T < 1 is consistent with the ratio ϕ of the width of the scalar profile to the width of the velocity profile being greater than one (Chen & Rodi 1980;van Reeuwijk et al 2016).…”

Section: The Entrainment Coefficientmentioning

confidence: 99%

The turbulent Prandtl number in a pure plume is 3/5

2017

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We derive a new expression for the entrainment coefficient in a turbulent plume using an equation for the squared mean buoyancy. Consistency of the resulting expression with previous relations for the entrainment coefficient implies that the turbulent Prandtl number in a pure plume is equal to 3/5 when the mean profiles of velocity and buoyancy have a Gaussian form of equal width. Entrainment can be understood in terms of the volume flux, the production of turbulence kinetic energy or the production of scalar variance for either active or passive variables. The equivalence of these points of view indicates how the entrainment coefficient and the turbulent Prandtl and Schmidt numbers depend on the Richardson number of the flow, the ambient stratification and the relative widths of the velocity and scalar profiles. The general framework is valid for self-similar plumes, which are characterised by a power-law scaling. For jets and pure plumes it is shown that the derived relations are in reasonably good agreement with results from direct numerical simulations and experiments.

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“…In fact, they were interested in the turbulent diffusion flames. The axisymmetric turbulent jets with strongly variable density were studied by several researchers like So and Zhu [34], Gouldin et al [11], Fulachier et al [9], Panchapakesan and Lumley [23], Purwanto [27], Pietri et al [26] and Gazzah et al [10]. These studies showed that the light jets generate an entrainment of the ambient air definitely more effective than heavy jets such as the carbon dioxide (CO 2 ).…”

Section: Introductionmentioning

confidence: 99%

Study of non-reactive isothermal turbulent asymmetric jet with variable density

Imine¹,

Imine²,

Abidat³

et al. 2005

Comput Mech

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In the present study, the effects of inlet isothermal jet geometry on the mixing process with variable density have been investigated numerically. Four density ratios were considered, namely R ρ =7.2, 1.8,1 and 0.66 for He-air, CH4-air, Air-air and CO2-air mixtures respectively. The jets are produced through rectangular and elliptic nozzles with aspect ratio Ar = 2:1. The elliptic and rectangular nozzles have approximately the same exit area as the circular nozzle. A second-order Reynolds stress model (RSM) is used to investigate variable density effects in asymmetric turbulent jets. Comparative studies are presented for the calculations of the variables such as the longitudinal velocity, the longitudinal fluctuating velocity and the turbulent kinetic energy.The results indicate that the asymmetric geometry noticeably enhances mixing in comparison with the axisymmetric case. Typical phenomenon of 3D jets is observed.

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Simultaneous measurements of temperature and velocity fluctuations in a slightly heated jet combining a cold wire and Laser Doppler Anemometry

Cited by 42 publications

References 26 publications

A local sensor for joint temperature and velocity measurements in turbulent flows

A local sensor for joint temperature and velocity measurements in turbulent flows

The turbulent Prandtl number in a pure plume is 3/5

Study of non-reactive isothermal turbulent asymmetric jet with variable density

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