节流通道振动对碳氢燃料不稳定流动的影响研究

Effects of Vibrating Throttle Channel on Flow Instability of Hydrocarbon Fuel

关键词:  节流结构  振动  流动振荡  流动分离  振动方向

Key words:  Throttle structure  Vibration  Flow oscillation  Flow separation  Vibration direction

摘要:

通过实验发现振动的节流通道会引起碳氢燃料的不稳定流动现象。为了探究节流通道振动引发碳氢燃料不稳定流动的机理，采用数值求解三维Reynold-Averaged Navier-Stokes（RANS）方程和k-ω湍流模型的方法研究了节流通道振动对流场动态特性的影响，重点关注节流通道振动对扩张结构附近流动分离的动态特性的影响。数值模拟节流结构两端压差与实验数据对比，验证了所采用的数值方法和湍流模型的有效性。结果表明，当燃油流动方向和节流通道振动方向一致时，会发生不稳定流动现象。当燃油流动方向和节流通道振动方向垂直时，不会发生不稳定流动现象。通过流场的动态分析，发现振动方向与流动方向一致时扩张结构附近非定常涡会发生轴向的周期性运动，从而导致了不稳定流动的现象。振动速度越大，不稳定流动程度越大。

Abstract:

The phenomenon of flow instability of hydrocarbon fuel caused by vibrating throttle channel was observed in experiment. In order to investigate the mechanism of flow instability， the effects of vibrating throttle channel on dynamic characteristics of flow field were numerically investigated using the three-dimensional Reynolds-Averaged Navier-Stokes （RANS） solution and k-ω turbulence model. The effects of the throttle channel vibration on the dynamic characteristics of flow separation near the expanding section were particularly studied. The numerical prediction of the pressure difference of throttle section was well agreement with the experimental data. The accuracy of the numerical method and turbulence model was validated. The obtained results show that the flow instability occurs when the fuel flow direction and the throttle channel vibration direction are the same. The flow instability will not occur when the fuel flow direction is perpendicular to the throttle channel vibration direction. The unsteady vortex near the expanding section moves periodically when fuel flow direction and the throttle channel vibration direction is the same， which leads to the flow instability. The greater the vibration velocity， the greater the flow instability is .