Investigation On The Influence Of Flow Control On Flow And Heat Transfer In Rectangular Channel

In the face of increasingly high-speed flight requirements and flight controllability and adjustment,higher requirements are placed on the reliability and efficiency of engine thermal protection,not only to meet the needs of thermal protection,but also to meet the needs of dynamic heat exchange and energy saving and high efficiency.Facing the extremely complex dynamic and extreme thermal environment,the existing traditional heat exchange methods restrict the efficiency of the engine.Taking the engine thermal protection as the background,this thesis studies the influence mechanism of the inner surface structure and channel configuration of the rectangular channel on the flow state and the enhanced heat transfer effect under the condition of single-sided heating,and analyzes the enhanced heat transfer efficiency,and cooling capacity under flow control.And through numerical calculation,the law of enhanced heat transfer in flow-controlled vortex state is well revealed,and the formation and generation mechanism of dynamic vortex,as well as its influence on flow and heat transfer characteristics,are studied and analyzed.From the simple and single stationary vortex generator to the composite enhanced heat transfer means,from the passive flow control technology to the active flow control technology,the comprehensive heat transfer efficiency can be improved by dynamic adjustment control,and the heat transfer enhancement problem of the single-side heated channel can be weakened and solved.The main investigation contents are as following:(1)Based on the cooling model of the liquid fuel engine thrust chamber wall and the cooling environment of high temperature and high pressure,the numerical simulation of the cooling and the heat transfer process is carried out.A three-dimensional regenerative cooling model is established,and the traditional smooth regenerative cooling channel is improved by the wall turbulent structure.The turbulent heat transfer is enhanced by a single stationary flow control structure(including ribs,spherical surfaces and other rough structures on the inner wall),through theoretical and numerical simulations,the turbulence-enhanced heat transfer efficiency and cooling performance under the stationary vortex generator are analyzed.At the same time,considering the possible pressure drop in flow,a parametric study of vortex generators such as ribs and spherical surfaces was carried out.The different structures and arrangements were designed,and the comprehensive heat transfer performance evaluation was carried out.The numerical investigation provides theoretical and numerical support for the practical application of turbulent enhanced heat transfer structure.(2)In view of the fact that a single stationary vortex generator cannot solve the problem of cross-section thermal stratification,a spherical fin composite flow control structure is established to realize the comprehensive performance optimization.Aiming at the dramatic changes in the hydrogen physical parameters in the regenerative cooling channel and the crosssection temperature stratification caused by single-side heating,the heat transfer models of different spherical composite structures are designed.The research shows that the new composite structure weakens the cross-sectional thermal delamination phenomenon and the negative influence of non-uniform distribution on the flow heat transfer effect.Through the detailed parametric study and the analysis of the non-uniform distribution characteristics under various structures,it can be concluded that new composite structure provides a technical reference for weakening the thermal delamination problems.(3)Considering the cooling and thermal protection requirements under extremely dynamic heat flux,a novel heat transfer enhancement method for dynamic control flow boundary layer disturbance was proposed.From the perspective of theoretical and numerical calculation,the enhancement convection heat transfer mechanism by boundary vibration was analyzed and discussed in detail.Using CFD dynamic grid technology from 2-D to 3-D structure,the influence of different vibration frequencies and amplitudes on flow and heat transfer were studied.The enhancement heat transfer mechanism was analyzed based on the Field Synergy Principle,and the effect of turbulence enhancement heat transfer under vibration boundary control was studied.Combined with the distribution of turbulent kinetic energy and Synergy Angle,the flow and heat transfer effect under dynamic control boundary was studied.The flowinduced enhancement heat transfer device and scheme were realized by active flow control.The effectiveness of the enhancement heat transfer method of dynamic control flow boundary was verified by numerical calculation.The results show that the dynamic control flow vortex can solve the local heat transfer deterioration problem and meet the demand of efficient dynamic heat transfer.(4)Aiming at the limitation that the boundary vibration vortex generator is easy to increase the flow resistance in the tube,and it is difficult to achieve in some places where the wall itself is very thin,an active vibration turbulence device inside flow channel is proposed.The influence of periodic horizontal disturbances and expansion-contraction disturbances on flow heat transfer are investigated.The dynamic flow control and boundary disturbances are realized by actively controlling the interpolated turbulence element,which not only realizes the enhancement of heat transfer by flow disturbance,but also better solves the problem of local heat transfer deterioration.At the same time,the active flow control technology can better realize high-efficiency and energy-saving heat exchange design,and dynamically change the vibration control parameters in time according to the needs of flow and heat transfer.Which realizes the optimization of flow heat transfer,and can better meet the needs of high-efficiency heat exchange under dynamic heat flux density.The contradiction between high efficiency heat transfer demand and flow resistance under dynamic heat flux density can be solved well.Through the study of different vibration parameters and vibration positions,it provides a technical reference for the development of new dynamic control technology to enhance heat transfer and thermal protection technology,and provides an effective cooling scheme for high speed aircraft engine in extremely dynamic thermal environment and high-efficiency cooling requirements.