The Analysis of Reserve Circulation in Air Drilling through Using CFD Techniques

The Analysis of Reserve Circulation in Air Drilling through Using CFD Techniques

The periodically fully developed laminar heat transfer and fluid flow characteristics inside a three dimensional wavy channel in a compact heat exchanger have been numerically investigated. Calculations were performed for various Reynolds number ranging from 100 to 1200 using commercial CFD code CFX 11. Effects of wavy heights, lengths, wavy pitches and channel widths on fluid flow and heat transfer were studied. The results show that overall Nusselt numbers and friction factors increase with the increase of Reynolds numbers. According to the local Nusselt number distribution along channel wall, the heat transfer may be greatly enhanced due to the wavy characteristics. In the geometries parameters considered, friction factors and overall Nusselt number always increase with the increase of wavy heights or channel widths, and with the decrease of wavy lengths or wavy pitches. Especially the overall Nusselt number significantly increase with the increase of wavy heights or channel widths, where the flow may become into transition regime with a penalty of strongly increasing in pressure drop.