Study On Flow And Heat Transfer Of Primary Surface Heat Exchanger For Aeroengine

In the development of advanced aeroengine technology,high efficient and compact heat exchanger has been regarded as the key factor to improve the efficiency of thermal management.Because of the improvements of aeroengine performance and requirements,the temperature of turbine inlets is increased and the amount of cooling air is also increased.At present,applying the heat exchanger to the aeroengine is a novel design concept.The application of the heat exchanger to the areoengine can improve the efficiency and performance of the aeroengine.The air from the high pressure compressor is cooled by the cooling air from external duct firstly,and then the cooled air is used for cooling the turbine blade.In this way,the application of the heat exchanger could reduce the total usage of the cooling air and improve the efficiency of the aeroengine.A number of studies show that the performance of heat exchanger will effect the performance and efficiency of aeroengine greatly.And because of the strict limitation of space and load in aeroengine,it is impossible to use regular heat exchanger but the one with high efficiency and compact.Primary surface heat exchanger is an advanced heat transfer equipment with the characteristics of small size,light weight and high integrated.Primary surface heat exchanger is a kind of heat exchanger of plate structure with advanced manufacturing technology and design concept.There are no second-surfaces in the primary surface heat exchanger and it not only can save materials,reduce the weight and cost,but also achieve higher heat transfer efficiency.At present,primary surface heat exchanger has been successfully applied in ships,vehicles and some military equipment and the application of primary surface heat exchanger have significantly improved the thermal efficiency,reduced the energy loss of the system.Because of these advantages of primary surface heat exchanger,it has great application prospect in aviation field.This paper revolves around the design and optimization method of primary surface heat exchanger for aeroengine.And the flow and heat transfer characteristics of primary surface heat exchanger are studied.The main research contents are as follows:Firstly,the summaries of the previous studies are presented briefly,including the basic research methods and conceptions in this field of research.Based on the summaries,the thermal calculations of the primary surface heat exchanger based on the number of heat transfer unit method and the structure characteristics of the heat exchanger are carried out.And the calculations of the heat exchanger are completed through the computer program based on Visual Basic 6.0.The program can provide a better design environment for the designer.Secondly,based on the real working conditions of an aeroengine,the numerical simulations of 0 ° straight channel primary surface heat exchanger under large Reynolds number are carried out.The validation of the numerical simulations is carried out by the comparison between the results of thermal calculations and the simulations.On the basis,the simulations of the heat exchanger with different cross angles(15°,30°and 45°)are carry out.The influence of different cross angles and working states(high altitude and low altitude)on the heat transfer and flow characteristics are analyzed.The best connection mode(parallel or series)of heat exchanger under different working conditions is also given.It provides a basis for the further optimization design and application of heat exchanger.Finally,the experiment studies of four different 3D printed heat exchanger(0°heat exchanger with smaller channel,15°,30°and 45°with regular channel)are carried out in the wind tunnel with the test system.The experimental results are compared with the thermal calculation firstly.And then the CFD model of whole heat exchanger is established and the simulation of whole heat exchanger is carried out.By comparing the results,it shows that the numerical simulation method is the most efficient and reliable method to study the heat transfer and flow characteristics of the primary surface heat exchanger.The thermal calculation method proposed,the methods of numerical simulation of the whole passage and the whole heat exchanger and the results given in this paper can provide the basis for optimizing design of the primary surface heat exchanger.But because the structure,the internal flow and heat transfer process of primary surface heat exchanger are very complex,and the 3D printing technology has many uncertainties,the research on the primary surface heat exchanger may lead to further developments.