In this paper, the dual underexpanded impinging jets are experimentally and numerically studied. The experiments were performed by measuring the unsteady and averaged wall static pressures and by visnalizing density f...In this paper, the dual underexpanded impinging jets are experimentally and numerically studied. The experiments were performed by measuring the unsteady and averaged wall static pressures and by visnalizing density fields using schlieren method. Numerical calculations were also conducted by solving unsteady three dimensional compressible Navier-Stokes equations with Baldwin-Lomax turbulence model. The main parametm''s for the dual jets are the non-dimensional distance between the two nozzle centers H/D covering 1.5, 2.0, the nozzle to plate separation L/D 2.0, 3.0,4.0 and 5.0 and the pressure ratio defined by Po/Pb 1.0-6.0, where D is the diameter of each nozzle exit, Po the stagnation pressure and Pb the back pressure. It is found that the agreement between the experiments and the calculations is good. The fountain flow at the middle of the two jets is observed both in the experiments and the calculation. According to FFT analysis of the experiments for the twin jets,relatively low frequgncy (up to 5 kHz) is dominant for H/D =1.5, L/D =2.0 and pressure rafio po/Pb =3.0 and 5.0,which is confLrmed by the experiments.展开更多
文摘在这份报纸，侵犯喷气的 underexpanded 的流动地从方面比率 1， 3 和 5 的矩形的嘴发出了数字地并且试验性地被学习。二维的温度和压力分布被使用红外线的照相机和分别地扫描设备和一台步进马达的一个压力的联合测量。侵犯的板上的停滞压力的变化表明 hysteretic 现象在为 3.0 和 5.0 的方面比率增加并且减少压力比率期间存在。方面比率 1.0 的嘴引起了最大的全部的压力损失 p c / p 0 =，这也被发现 0.27 在 p 的压力比率 0 / p b = 6.5 在 p c 是墙上的停滞中心压力的地方， p 0 在上游的停滞压力， p b 周围的压力。另外的二张嘴证明压力损失 p c / p 0 =0.52 并且 0.55 被方面比率的嘴完成 3,0 和 5.0 分别地。在计算和实验之间的比较相当好，出现三维在喷气冲击波优化并且组织。然而，在在 3.5 和 4.5 的压力比率之间的实验观察的压力变化的磁滞现象不能在计算被证实。关键词可压缩的流动 - 冲击波 - 下面膨胀的矩形的侵犯喷气 - CFD CLC 数字
文摘In this paper, the dual underexpanded impinging jets are experimentally and numerically studied. The experiments were performed by measuring the unsteady and averaged wall static pressures and by visnalizing density fields using schlieren method. Numerical calculations were also conducted by solving unsteady three dimensional compressible Navier-Stokes equations with Baldwin-Lomax turbulence model. The main parametm''s for the dual jets are the non-dimensional distance between the two nozzle centers H/D covering 1.5, 2.0, the nozzle to plate separation L/D 2.0, 3.0,4.0 and 5.0 and the pressure ratio defined by Po/Pb 1.0-6.0, where D is the diameter of each nozzle exit, Po the stagnation pressure and Pb the back pressure. It is found that the agreement between the experiments and the calculations is good. The fountain flow at the middle of the two jets is observed both in the experiments and the calculation. According to FFT analysis of the experiments for the twin jets,relatively low frequgncy (up to 5 kHz) is dominant for H/D =1.5, L/D =2.0 and pressure rafio po/Pb =3.0 and 5.0,which is confLrmed by the experiments.
