Flow Distribution Characteristics of Supercritical Hydrocarbon Fuel in Parallel Channels with Pyrolysis

超临界裂解煤油的并联通道流量分配特性研究

School of Astronautics, Northwestern Polytechnical University, Xi’an 710072, China

Received: 8 January 2018

Abstract

Due to the asymmetric geometry of flowpath and combustion organization, the heat flux distribution on RBCC's walls are extremely non-uniform. With a validated numerical model considering the changes of thermophysical properties and chemical components, the present study analyzed the effects of heat flux intensity, non-uniformity of heat flux distribution and inlet manifold on the mass flow distribution of parallel regenerative cooling channels. Results show that the intensity of heat flux enlarges the non-uniformity of parallel channels, however, the non-uniformity is reduced when the outlet temperature is above the completely pyrolysis value; and the non-uniformity heat flux distribution increases the mal-distribution of parallel channels dramatically, the difference of mass flow rate reaches to 33.2% when the heat flux difference is only 0.25 MW/m²; increasing the flow area of inlet manifold would improve the flow distribution of parallel channels with decrease of heat transfer efficiency and increases of pressure drop.

摘要

以周向热流分布极为不均匀的RBCC发动机为应用背景，采用经过校验的高精度数值仿真方法，基于超临界裂解煤油开展了并联再生冷却通道流量分配特性的三维数值模拟研究，分析了壁面热流强度、非均匀热流以及入口集液腔对并联再生冷却通道流量分配特性的影响规律。结果表明，当均匀热流条件下的热流强度增大时，分支管不均匀分配特性增强，但是当壁面加热量使得给定质量流率的煤油出口温度大于完全裂解温度时，非均匀分配特性有所缓和；壁面非均匀加热时，会造成分支管流量不均匀度急剧增大，且热流越大的分支管对应的质量流量越小，进而增大了该位置发生壁面超温的可能性，在热流相差仅0.25 MW/m²时，分支管热流相差最大为33.2%；通过增大入口集液腔流通面积可以改善并联分支管的流量分配特性，但是同时也会带来换热效率降低和压降增大的影响，在所研究工况中，入口集液腔为分支管总流通面积的4倍时，可以得到一个较好的流量分配特性。