航空发动机1 次表面换热器流动换热性能分析

为了研究航空发动机1次表面换热器流动换热性能,基于传热单元数法并结合其结构特性,建立了换热器热力学设计方法并对经典热力学公式进行了对比分析。同时针对适用于航空发动机的4种不同结构形式1次表面换热器(直通道逆流型和1 5°,30°及45°叉流型),在真实工况下的流动换热特性开展了数值模拟研究。通过对比不同结构换热器在不同工况下的流动换热特点,可以为一次表面换热器芯体核心部件的优化设计提供设计依据和方法。基于数值计算结果,对比分析了不同交错角度θ对换热器的换热性能与流动特性的影响。结果表明:对于直通道逆流换热器,整个换热器内部温度有规律均匀分布;对于叉流换热器,由于波纹板片呈一定角度交替放置,内部流动复杂,局部存在明显的涡流强化换热,气体流动通道内的速度、温度分布极不均匀。随着交错角度的不断增大,叉流换热器的换热性能不断增强,但其冷热两侧压降也大幅增大。

Analysis of Flow and Heat Transfer Performance of Primary Surface Heat Exchanger for Aeroengine

In order to investigate the performance of Primary Surface Heat Exchanger(PSHE)for aeroengine, the thermal calculations of PSHE based on the number of heat transfer unit method and the structure characteristics of the heat exchanger were carried out. This paper focused on four different structural models of the PSHE (straight channel heat exchanger and cross flow heat exchanger of 15°, 30° and 45°). Numerical simulations were carried out in the real condition of an aeroengine to analysis the flow and heat transfer characteristics of the PSHE. The design and calculation method of the PSHE core can be optimized by comparing the flow and heat transfer characteristics of heat exchangers with different structures under different working conditions. The contrastive analysis of the influence of different interleaving angle θ on the heat transfer performance and fluid characteristics of heat exchanger were carried out based on numerical calculation results. The results show that the temperature distribution in the whole heat exchanger is uniform for the straight channel heat exchanger. For the cross flow heat exchanger, due to the corrugated plates are placed with cross angle alternately, the internal flow patterns are complex. There were obvious eddies in some areas, the internal velocity and temperature distribution of the PSHE is extremely uneven. With the increasing of cross angle, the heat transfer performance of the heat exchanger is continuously enhanced, but the pressure drop on both sides increases greatly.