The flow field characteristics and heat transfer characteristics of a spiral channel with different relative jet tube insertion depths(δ =0-0.625)have been analyzed by numerical simulation.The results show that with an increase in δ,the distance from the jet core region to the outer wall becomes shorter,and the range of secondary vortexes on both sides of the jet tube at the jet incident position also increases,thus enhancing the impact of the flu-id on the top and bottom walls.The local Nusselt numbers Nuc on the top and bottom heat transfer walls show the same variation as δ,and the optimal heat transfer position(the location of the largest Nuc)becomes closer to the outside wall with increasing δ.The Nuc of the inner wall surface decreases with increasing δ in the inner range of the jet pipe wall,whilst Nuc increases with increasing δ in the outer range.Increasing the insertion depth of the jet tube results in the most significant improvement in the heat transfer performance of the outer wall of the spiral chan-nel.The cross-section Nusselt number Nuθ shows three distinct regions with increasing spiral angle γ,namely the inlet region,the jet influence region and the outlet region.The Nuθ of the inlet and outlet regions remains stable with the variation in γ,but the Nuθ of the outlet region is about 19％higher than that of the inlet region.The maxi-mum value of Nuθ is located at about 5° downstream of the jet incident point.In the range of spiral angle from-15° to 45°,the jet has the greatest influence on heat transfer.The influence range of heat transfer is essentially independent of the insertion depth of the jet tube.The comprehensive heat transfer evaluation index(PEC)initially increases and then decreases with increasing δ,and a spiral channel with δ =0.250 shows the best comprehensive heat transfer performance.
关键词
数值模拟/螺旋通道/射流管/传热性能
Key words
numerical simulation/spiral channel/jet tube/heat transfer performance
维普
万方数据