The Optimization Of Laminar Flow Field Of Channel Flow Based On Entransy Extreme Principle

For a long time, the optimization of heat transfer process is mainly based on experience and test, and the lack of theoretical guidance. In recent years, the development of enhanced heat transfer technology is developing rapidly, in the study of heat transfer enhancement mechanisms, progress has also been made many breakthrough, the main theory are entropy maximum principle, the field synergy principle and entransy dissipation theory. At present mainly in circular tube and elliptical tube application of entransy dissipation extremum principle for solving convection heat transfer optimization flow, has certain limitations, so it is necessary to explore the characteristics of optimal flow field and other shapes in the channel. In this paper, simulation and optimization of various types of pipe channel and a square channel using numerical, can meet the optimal flow entransy dissipation extremum principle, and to analyze its characteristics.Based on the energy equation derived heat transfer process of the minimum fire can be applied to the heat transfer process of the entransy dissipation principle and numerical calculation of the entransy dissipation extremum principle derived from the convective heat flow equations based on the optimization of flow field optimization, circular tube, oval tube and rectangular pipe laminar flow and heat transfer in a square channel was obtained. Through the analysis, the optimization flow outside the pipe laminar convective heat and a variety of laminar flow in a square channel heat exchanger are manifested as multiple longitudinal vortex structure. Compared with the original flow, optimization of flow field can increase the minor premise in resistance to greatly improve the heat convection effect, that flow pattern of longitudinal vortex is a general flow pattern of laminar flow and heat transfer enhancement.Casing pipe flow in longitudinal vortex structure inside the channel can be achieved by adding the spoiler. In this paper, adding forward, radial and reverse spoiler on the casing pipe. The results show that the spoiler can longitudinal vortex formation channel in the casing pipe, longitudinal vortex flow changes the temperature field of the original, promote regional mainstream fluid and near wall fluid mixing, thinning of the thermal boundary layer heat transfer near the wall, increasing the temperature gradient, enhanced the effect of heat transfer. The tilt direction spoiler can not only strength, size of longitudinal vortex generated by the impact, will affect the direction of the vortex, so the spoiler different tilt direction has the effect of heat transfer enhancement is different. In this paper we study the Re range, reverse spoiler integrated heat transfer enhancement effect is best. Study on effect of heat transfer enhancement of reverse spoiler on diflerent angle, results show that reverse spoiler different angle has the effect of heat transfer enhancement is different, dip spoiler is large, the resistance is greater, reverse spoiler angle30°and45°of the integrated heat transfer enhancement effect is best.For laminar staggered scaling trapezoidal channel heat transfer numerical simulation, results show that due to the change of section shape staggered scaling trapezoidal channel, the fluid is formed in the channel two flow, two flow in the channel into multiple longitudinal vortex, the vortex is facilitated by the presence of mixed fluid near the wall and regional mainstream fluid, thinning of the thermal boundary layer near the wall surface of heat transfer, increase the temperature gradient, so the alternating scaling trapezoidal channel has the effect of heat transfer enhancement is excellent. Numerical simulation of the three structural parameters for laminar flow10-7,10-5,10-3staggered scaling trapezoidal channel heat transfer, numerical calculation results show that in the range of Re,10-3staggered scaling trapezoidal channel heat effect is best, explain cross-sectional variation of fault scaling trapezoidal channel rate is higher, the better effect of heat transfer. Laminar flow of different scaling cycle staggered scaling trapezoidal channel heat transfer numerical simulation, results show that the numerical scale cycle range, staggered scaling trapezoidal channel scaling cycle is small, strengthening the better effect of heat transfer channel.