EFFECT OF HEATED WALL POSITION ON MIXED CONVECTION IN A CHANNEL WITH AN OPEN CAVITY

In this paper mixed convection in an open cavity with a heated wall bounded by a horizontal unheated plate is investigated experimentally. The cavity has the heated wall on the opposite side of the forced inflow. The results are reported in terms of wall temperature profiles of the heated wall and flow visualization for Reynolds number (Re) from 100 to 2000 and Richardson number (Ri) in the range 4.3–6400; the ratio between the length and the height of cavity (L/D) is in the range 0.5–2.0 and the ratio between the channel and cavity height (H/D) is equal to 1.0. The present results show that at the lowest investigated Reynolds number the surface temperatures are lower than the corresponding surface temperature for Re = 2000, at same the ohmic heat flux. The flow visualization points out that for Re = 1000 there are two nearly distinct fluid motions: a parallel forced flow in the channel and a recirculation flow inside the cavity. For Re = 100 the effect of a stronger buoyancy determines a penetration of thermal plume from the heated plate wall into the upper channel. Moreover, the flow visualization points out that for lower Reynolds numbers the forced motion penetrates inside the cavity and a vortex structure is adjacent to the unheated vertical plate. At higher Reynolds number the vortex structure has a larger extension at same L/D value.

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Numerical Study on Mixed Convection in Porous Media in a Channel With an Open Cavity Below

Volume 7: Fluid Flow, Heat Transfer and Thermal Systems, Parts A and B ◽

10.1115/imece2010-40574 ◽

2010 ◽

Author(s):

Bernardo Buonomo ◽

Oronzio Manca ◽

Paolo Mesolella ◽

Sergio Nardini

Keyword(s):

Mixed Convection ◽

Numerical Study ◽

Fluid Dynamic ◽

Vertical Wall ◽

Open Cavity ◽

Temperature Fields ◽

Forced Flow ◽

Heated Wall ◽

Local Thermal Equilibrium ◽

Uniform Heat Flux

A numerical analysis of mixed convection in gas saturated metal foam in a horizontal channel with an open cavity heated at uniform heat flux on a vertical wall is studied numerically. Non-local thermal equilibrium and Brinkman-Forchheimer-extended Darcy model are assumed. Boussinesq approximation with constant thermophysical proprieties are considered. Results are carried out for an aluminium foam with 10 PPI and ε = 0.909, the fluid is air and for the assisting case. Results, for different Peclet and Rayleigh numbers, are given in terms of solid and fluid wall temperatures and local Nusselt numbers and stream function and temperature fields. Results show that diffusive effect determined lower temperature values inside the solid and the fluid temperatures are higher in all considered cases. The interaction between the forced flow in the channel and the buoyancy due to the heated wall determines different thermal and fluid dynamic behaviors.

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Experimental Investigation on Mixed Convection in a Channel With an Open Cavity Below

Heat Transfer: Volume 1 ◽

10.1115/ht2003-47132 ◽

2003 ◽

Author(s):

Oronzio Manca ◽

Sergio Nardini ◽

Ruggero Pitzolu ◽

Kambiz Vafai

Keyword(s):

Mixed Convection ◽

Flow Visualization ◽

Open Cavity ◽

Forced Flow ◽

Heated Wall ◽

Heated Plate ◽

Thermal Plume ◽

Recirculation Flow ◽

Nusselt Numbers ◽

Flow And Heat Transfer

Mixed convection in an open cavity with a heated wall bounded by a horizontal unheated plate is investigated experimentally. The cavity has the heated wall on the inflow side. Mixed convection fluid flow and heat transfer within the cavity is governed by the buoyancy parameter, Richardson number (Ri), and the Reynolds number (Re). The results are reported in terms of wall temperature profiles of the heated wall and flow visualization for Re = 100 and 1000, Ri in the range 30–110 (for Re = 1000) and 2800–8700 (for Re = 100), the ratio between the length and the height of cavity (L/D) is in the range 0.5–1.5 and the ratio between the channel and cavity heights (H/D) equal to 0.5 and 1.0. The present results show that the maximum dimensional temperature rise values decrease as the Reynolds and the Richardson numbers decrease. The flow visualization points out that for Re = 1000 there are two nearly distinct fluid motions: a parallel forced flow in the channel and a recirculation flow inside the cavity. For Re = 100 the effect of a stronger buoyancy determines a penetration of thermal plume from the heated plate wall into the upper channel. The dimensionless maximum wall temperatures in terms of L/D had values in ± 5% respect to an average function. Nusselt numbers increase when L/D increase in the investigated range of Richardson numbers.

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