Influence of spanwise pitch on local heat transfer distribution for in-line arrays of circular jets with spent air flow in two opposite directions

2008 ◽  
Vol 33 (1) ◽  
pp. 84-95 ◽  
Author(s):  
Vadiraj Katti ◽  
S.V. Prabhu
Author(s):  
Shigeki Hirasawa ◽  
Tsuyoshi Kawanami ◽  
Katsuaki Shirai

We studied the forced convection heat transfer performance and pressure drop of high permeability metal cellular porous media in air flow using a 3-dimensional thermofluid computation code. The temperature and velocity distributions in the air flow region, local heat transfer coefficient, and local heat flux on the surface of the porous media were numerically calculated for steady air flow by changing the parameters of the pore size and air velocity. The cellular porous media were modeled by pin array, cube geometry, and truncated octahedron geometry using thin wires. The diameter of the wires was 0.1 mm, and the pore per inch (PPI) was 5–50. The relations between the Nusselt number using the volumetric heat transfer coefficient and the Reynolds number were obtained from our calculation results, and we compared them with conventionally proposed experimental correlations. Also, the pressure drop calculation result was compared with conventionally proposed experimental correlations. The following results were obtained. The local heat transfer coefficient and local heat flux on the surface of porous media were small near the joint positions of the wires of the cellular porous media because of the thermal boundary layer. The volumetric heat transfer coefficient and pressure drop agreed with conventionally proposed experimental correlations within errors of twice the volumetric heat transfer coefficient and pressure drop. The relation between the heat transfer rate per unit volume and the heat transfer area per unit volume agreed with the convection heat transfer correlation for a tube bundle.


Author(s):  
Shou-Shing Hsieh ◽  
Jung-Tai Huang

An experimental study was performed in a confined circular single jet impingement. The effect of jet Reynolds number, nozzle-to-plate spacing and heat flux levels on heat transfer characteristics of the heated target surface was examined and presented. Flow visualization was made to broaden our fundamental understanding of the physical process of the type of flow. Transition and turbulent regimes are identified. The local heat transfer coefficient along the surface is measured and correlation of the stagnation point Nusselt number are presented and discussed.


Author(s):  
G. J. Hwang ◽  
C. R. Kuo ◽  
C. Y. Chang

Experimental study on the convective heat transfer of radial air flow in rotating multi-channels was performed. Three sets of test sections, one single-flow passage, one nine-flow passages and one twenty-five-flow passages with the same cross sectional area of 9π mm2, were applied to the experiments. The test section was formed by rectangular blocks of aluminum alloy with circular flow passages. Between two adjacent blocks, a Bakelite board of 1 mm thickness was placed to separate axial wall heat conduction for local heat transfer measurement. The parameters involved are the Reynolds number Re, the Rotation number Ro, the Buoyancy parameter Gr/Re2, and the ratio of the heat transfer area Ap/Ac. The heat transfer results of radially rotating circular ducts based on per-passage and per-system were obtained.


Sign in / Sign up

Export Citation Format

Share Document