论文部分内容阅读
为了深入分析淹没水射流流动特征,综合采用数值模拟和流场测量进行研究.数值模拟应用基于S-A模型的DES方法,并通过圆柱绕流验证数值方法的有效性;流场测量采用粒子图像测速技术.研究表明:采用的数值模拟方案可以准确预测圆柱的升力系数、阻力系数和尾流中旋涡脱落的斯特劳哈数;模拟和实验获得的射流速度沿轴向和径向的衰减规律吻合;模拟获得的射流半值宽度线的斜率小于实验结果,主要是由于对剪切层厚度的预测不足所致;在垂直于射流束横截面上,涡量呈现双峰分布;射流的涡量随着射流发展呈总体衰减趋势.“,”Numerical simulation and flow measurement are performed to explore the flow characteristics of submerged waterjet.The numerical simulation is based on the DES method and S-A model,and the validity of the numerical scheme is substantiated with flows around a circular cylinder.Particle image velocimetry is utilized to obtain flow velocity distribution.The results show that the lift and drag coefficients of the cylinder and the Strouhal number of the vortex shedding in the wake are accurately predicted with the numerical technique.Regarding the waterjet,numerically obtained jet velocity attenuation in streamwise and lateral directions agrees well with the experimental results.The approximate slope of the semi-width curve numerically obtained is smaller than its counterpart associated with experiment,as is mainly ascribed to the underestimation of the shear layer thickness with numerical approach.Dual-peak distribution of vorticity arises on the cross section of the waterjet stream.Vorticity magnitude decreases with the jet progression.