Effect of Freestream Motion on Heat Transfer Characteristics of Turbulent Offset Jet

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Sushil Kumar Rathore ◽  
Manab Kumar Das
Keyword(s):  
Heat Transfer ◽  
Surrounding Medium ◽  
Local Maximum ◽  
Streamwise Velocity ◽  
Jet Flow ◽  
Heat Transfer Characteristics ◽  
Freestream Velocity ◽  
Transfer Characteristics ◽  
Nusselt Number Distribution ◽  
Offset Jet

The numerical simulation of turbulent offset jet flow has been carried out using k–ω shear stress transport (SST) model. The simulations have been done for the offset jet flow in the quiescent medium and also in the presence of an external stream. The effect of freestream velocity on the flow and heat transfer characteristics of turbulent offset jet has been reported. The offset ratio and Reynolds number of flow considered are 5.7 and 16,000, respectively. The presence of coflow stream has been found to reduce the entrainment of surrounding fluid into the jet which in turn reduces the heat transfer from the jet to the surrounding medium. The effect of freestream velocity on the important parameters like decay of the local maximum streamwise velocity, jet spread, reattachment length, velocity logarithmic profile, velocity defect law profile, decay of the local maximum streamwise temperature, variation of wall temperature, temperature similarity profile, and Nusselt number distribution has been discussed.

Local and Instantaneous Heat Transfer Characteristics of Arrays of Pulsating Jets

1999 ◽  
Vol 121 (2) ◽  
pp. 341-348 ◽  
Author(s):  
H. S. Sheriff ◽  
D. A. Zumbrunnen
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Jet Flow ◽  
Impinging Jets ◽  
Industrial Applications ◽  
Heat Transfer Characteristics ◽  
Ensemble Averaging ◽  
Transfer Characteristics ◽  
Pulsating Jets

Recent investigations have revealed that pulsations in an incident jet flow can be an effective technique for modifying convective heat transfer characteristics. While these studies focused on single impinging jets, industrial applications of impinging jets usually involve arrays of jets. To explore the effects of flow pulsations on the heat transfer performance of jet arrays, an experimental investigation has been performed of instantaneous and time-averaged convective heat transfer to a square, in-line array of circular air jets within an unit cell of the array. Hot-film anemometry was used to document the jet flow field. Instantaneous and time-averaged convective heat transfer rates were measured using a heat flux microsensor. An ensemble averaging technique was used to separate the pulsating component of flow velocity and heat transfer from the turbulent components and thereby assess the effect of flow pulsation on turbulence intensity and heat transfer. For the ranges of parameters considered, results indicate convective heat transfer distributions become more uniform in response to pulsations but heat transfer is not enhanced. Improved uniformity can be a useful aspect in many jet applications.

Analysis of Conjugate Heat Transfer for a Combined Turbulent Wall Jet and Offset Jet

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Tanmoy Mondal ◽  
Abhijit Guha ◽  
Manab Kumar Das
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Conjugate Heat Transfer ◽  
Wall Jet ◽  
Fluid Interface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
The Mean ◽  
Turbulent Wall ◽  
Offset Jet

This paper presents a study of the conjugate heat transfer, involving conduction through a solid slab and turbulent convection in fluid, for a combined turbulent wall jet and offset jet flow using unsteady Reynolds averaged Navier–Stokes (URANS) equations. The conduction equation for the solid slab and convection equation for the fluid region are solved simultaneously satisfying the equality of temperature and heat flux at the solid–fluid interface. The fluid flow is complex because of the existence of periodically unsteady interaction between the two jets for the chosen ratio of jets separation distance to the jet width (i.e., d/w = 1). The heat transfer characteristics at the solid–fluid interface have been investigated by varying various important parameters within a feasible range: Reynolds number (Re = 10,000–20,000), Prandtl number (Pr = 1–4), solid-to-fluid thermal conductivity ratio (ks/kf = 1000–4000), and nondimensional solid slab thickness (s/w = 1–10). The bottom surface of the solid slab has been maintained at a constant temperature. The mean conjugate heat transfer characteristics indicate that the mean local Nusselt number along the interface is a function of flow (Re) as well as fluid (Pr) properties but is independent of solid properties (ks and s). However, the mean interface temperature and mean local heat flux along the interface always depend on all the aforementioned properties.

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