节流通道振动对流动振荡的数值模拟研究

在由于超燃冲压发动机空间狭小,经常通过测量节流结构的压差来反算燃料流量。然而,我们在实验中发现渐缩渐扩结构通道在振动环境中会引起燃料的流动振荡现象,具体体现在喉部两端压差发生周期性变化,导致流量测量出现偏差,甚至会导致传热恶化和结构的损坏。为了了解流动振荡的机制,我们建立了渐缩渐扩通道的三维模型,并通过实验数据进行了验证。本文分析了振动环境下渐缩渐扩通道中流体动力学特性,研究了不同条件下稳定流场和非稳定流场,分析了雷诺数和振动强度对流动振荡的影响。研究表明,管道振动方向和流动方向一致时,导致流动分离区域和主流区域周期性的运动,从而导致流动振荡现象。流体雷诺数、振动强度和振动频率会影响流动分离区域的运动,从而影响到流动振荡。本文解释了振动环境下的渐缩渐扩管道的流动振荡现象,为流量计的设计提够了理论指导。

Numerical Study on Flow Oscillation in a Vibrating Throttle Channel

Due to small space of the hypersonic vehicle, the pressure drop of throttle channel is often used to measure flow rate. However, we found in the experiment that the vibration of throttle channel would lead to the flow oscillation. The flow oscillation of fuel significantly affected the flow measurement of fuel and even threatened the safety of the filling process. In order to understand the mechanism of flow oscillation, a three-dimensional model of the contracting and expanding passage with hydrocarbon fuel was established. After validation of the present model with experimental results, a detailed discussion has been performed to study the hydrodynamic characteristics of flow oscillation in contracting and expanding passage subject to vibration. The behaviors of steady flow fields and unsteady flow fields under different conditions were investigated. The results show that the axial vibration leads to flow oscillation. The reason is that flow separation region and mainstream region are periodic moving under axial vibration condition. The inlet Reynolds number of fuel, the amplitude and frequency of vibration velocity have a great influence on flow dynamic behavior. The flow oscillation in a vibrating throttle channel is analyzed, which provides the theoretical guidance for the design of the flowmeter.