边界条件对变循环发动机多维度仿真模型的影响研究

Effects of Boundary Conditions on Multi-Level Variable Cycle Engine Simulation Model

关键词:  变循环发动机  核心机驱动风扇级  维度缩放  迭代耦合方法  边界条件

Key words:  Variable cycle engine  Core driven fan stage  Zooming  Iterative coupled approach  Boundary condition

摘要:

为了研究变循环发动机（Variable Cycle Engine，VCE）多维度仿真模型中整机零维仿真模型与核心机驱动风扇级（Core Driven Fan Stage，CDFS）三维仿真模型之间边界参数传递处理方式对计算结果的影响，建立了CDFS和前可变面积涵道引射器（Forward Variable Area Bypass Injector，FVABI）耦合三维仿真模型及CDFS单部件三维仿真模型，对比了CDFS工作特性及出口区域静压分布的差异，并采用迭代耦合方法将CDFS工作特性耦合于循环参数分析，研究了CDFS出口静压分布差异对VCE多维度仿真模型计算结果的影响。结果表明，耦合仿真模型中CDFS稳定工作范围随着内涵出口静压变化而变化，其数值喘振点的换算流量与CDFS单部件仿真模型存在明显的差异。FVABI部件的存在降低了内涵出口及FVABI出口的平均静压边界条件对CDFS出口区域静压分布的影响，而且CDFS内、外涵流量分配会显著影响CDFS出口区域的静压分布。因此，由耦合仿真模型得到的CDFS出口区域静压分布更为真实、合理。超声速巡航工况下，相较于在CDFS出口使用平均静压边界条件，VCE多维度仿真模型在使用真实静压分布之后，CDFS内涵压比和等熵效率基本不变，CDFS外涵压比和等熵效率分别降低了0.86%和2.27%，导致VCE推力升高了0.41%，且迭代次数大幅降低。

Abstract:

In order to study the effects of the processing method of boundary parameters transfer between the zero-dimensional engine simulation model and the three-dimensional core driven fan stage（CDFS） simulation model in the multi-level variable cycle engine（VCE） simulation model on the simulation result， the three-dimensional coupled simulation model for CDFS and forward variable area bypass injector（FVABI） is established in this paper， as well as three-dimensional single CDFS simulation model. The differences in CDFS working characteristics and static pressure distribution around CDFS outlet obtained from the two three-dimensional simulation models are compared. Then both the CDFS working characteristics are integrated into cycle parameter analysis with iterative coupled approach to investigate the effect of the difference in static pressure distribution at CDFS outlet on the simulation result of multi-level VCE simulation model. The results indicate that the stable working range of CDFS in the three-dimensional coupled simulation model is affected by the static pressure at core outlet and the corrected mass flow rate of numerical surge point is different from that of three-dimensional single CDFS simulation model. The existence of FVABI reduces the influence of boundary conditions of averaged static pressure at core outlet and FVABI outlet on the static pressure distribution around CDFS outlet， and the mass flow rate distribution between CDFS core and bypass can significantly affect the static pressure distribution around CDFS outlet. Therefore， the static pressure distribution around CDFS outlet obtained from three-dimensional coupled simulation model is more realistic and reasonable. Compared with the results obtained from boundary condition of averaged static pressure， the pressure ratio and isentropic efficiency of CDFS core is not changed significantly， and the pressure ratio and isentropic efficiency of CDFS bypass are reduced by 0.86% and 2.27%，respectively， when the realistic static pressure distribution are employed at CDFS outlet in multi-level VCE simulation model under supersonic cruise condition， resulting in a 0.41 % increase in VCE thrust and a significant reduction in number of iterations.