The control of energy in various industrial applications passes by the comprehension of the phenomena of transfers especially in complex flows. The structure of the turbulent flow in the cavities in rotation depends o...The control of energy in various industrial applications passes by the comprehension of the phenomena of transfers especially in complex flows. The structure of the turbulent flow in the cavities in rotation depends on several parameters like the Reynolds number of rotation Ra and the aspect ratio of the cavity. The purpose of this work is to simulate numerically the effect of the aspect ratio on the level of turbulence in the annular steady flow with an incompressible fluid for three different configurations. In the first, the interior cylinder is fixed and the external is moving. The second configuration is the reverse. The third is the contra-rotating cylinders. For all these configurations, we varied the aspect ratio from 0.5 to 2.5. The numerical tool is based on a statistical model in a point using the closing of the second order of the transport equations of the Reynolds stresses （Reynolds Stress Model： RSM）. The results of our numerical simulation show that this geometrical parameter can be an interesting factor to increase the level of turbulence that is often required in several industrial applications where the economy and the control of energy are always required.展开更多
In many engineering practices, frequently an impulsive wave is a consequence of discharge of a shockwave from the exit of a tube, leading to an annoying noise like a sonic boom. The impulsive noisehas often been a maj...In many engineering practices, frequently an impulsive wave is a consequence of discharge of a shockwave from the exit of a tube, leading to an annoying noise like a sonic boom. The impulsive noisehas often been a major factor to limit the performance of flow devices as well as to affect hazardousinfluences on human being. The current paper describes a new control method for the reduction ofimpulsive wave. An experiment using a simple shock tube was carried out to examine the effect of acavity/helical vane system on the impulsive wave strength. The resulting impulsive wave was influencedby the detailed configuration of the belieal vane inside the cavity which is located at the vicinity ofthe exit of a tube. The effect of the belieal vane was compared with no belieal vane tests to ensurevalidation of this kind of control strategy. The results showed that the strength of the impulsive wavecould be significantly reduced by the current passive control using the cavity/helical vane system.展开更多
文摘The control of energy in various industrial applications passes by the comprehension of the phenomena of transfers especially in complex flows. The structure of the turbulent flow in the cavities in rotation depends on several parameters like the Reynolds number of rotation Ra and the aspect ratio of the cavity. The purpose of this work is to simulate numerically the effect of the aspect ratio on the level of turbulence in the annular steady flow with an incompressible fluid for three different configurations. In the first, the interior cylinder is fixed and the external is moving. The second configuration is the reverse. The third is the contra-rotating cylinders. For all these configurations, we varied the aspect ratio from 0.5 to 2.5. The numerical tool is based on a statistical model in a point using the closing of the second order of the transport equations of the Reynolds stresses （Reynolds Stress Model： RSM）. The results of our numerical simulation show that this geometrical parameter can be an interesting factor to increase the level of turbulence that is often required in several industrial applications where the economy and the control of energy are always required.
文摘In many engineering practices, frequently an impulsive wave is a consequence of discharge of a shockwave from the exit of a tube, leading to an annoying noise like a sonic boom. The impulsive noisehas often been a major factor to limit the performance of flow devices as well as to affect hazardousinfluences on human being. The current paper describes a new control method for the reduction ofimpulsive wave. An experiment using a simple shock tube was carried out to examine the effect of acavity/helical vane system on the impulsive wave strength. The resulting impulsive wave was influencedby the detailed configuration of the belieal vane inside the cavity which is located at the vicinity ofthe exit of a tube. The effect of the belieal vane was compared with no belieal vane tests to ensurevalidation of this kind of control strategy. The results showed that the strength of the impulsive wavecould be significantly reduced by the current passive control using the cavity/helical vane system.
