Flow structure and mixing properties by the baffle shape are numerically studied for a baffled micro combustor. The baffle shape is changed by various fuel and hole sizes. The numerical simulations based on different ...Flow structure and mixing properties by the baffle shape are numerically studied for a baffled micro combustor. The baffle shape is changed by various fuel and hole sizes. The numerical simulations based on different geometric conditions are performed by using the Reynolds Stress Model. The fuel-air mixing is greatly affected by flow recirculations. The centrally located flow recirculation has an important role for the entire mixing performance. The results show that this feature depends on the baffle configurations, and the baffle with small air holes represents efficient characters.展开更多
Turbulent jet flows with noncircular nozzle inlet are investigated by using a Reynolds Stress Model. In order to analyze the effects of noncircular inlet, the cross section of inlet are selected as circular, square, a...Turbulent jet flows with noncircular nozzle inlet are investigated by using a Reynolds Stress Model. In order to analyze the effects of noncircular inlet, the cross section of inlet are selected as circular, square, and equilateral triangular shape. The jet half-width, vorticity thickness, and developments of the secondary flow are presented. From the result, it is confirmed that the secondary flows of square and equilateral triangular nozzle are more vigorous than that of the circular jet. This development of secondary flows is closely related to the variations of vortical motions in axial and azimuthal directions.展开更多
Flow and heat transfer characteristics of a channel with oblique plates which are mounted periodically on the channel wall have been numerically investigated in a laminar range. The main objective of the present study...Flow and heat transfer characteristics of a channel with oblique plates which are mounted periodically on the channel wall have been numerically investigated in a laminar range. The main objective of the present study is to find the effect of the tilt angle of oblique plate on pressure drop and heat transfer characteristics in unsteady states. To get the different conditions of the heat transfer and flow evolution, two key parameters of the Reynolds number and the tilt angle of oblique plate are considered. At Re=200,600 , the tilt angles are changed for the range of 50°- 130°. The computational results show that the heat transfer and pressure drop are strongly dependent on the tile angle and Reynolds number. When the flows are unsteady, the tilt angle has an important role in the heat transfer enhancement. Oscillatory structures induce the better mixing of the thermal field and promote the wall heat transfer. For a constant plate length, the wall heat trans- fer is maximized near the 90°- 100°. This is strongly coupled with the variations of flow mixing induced by the oblique plate.展开更多
Unsteady flows in a channel with oblique plates have been numerically investigated. The oblique plates as disturbance promoters are installed at the upper wall. Unsteady characteristics are examined for Re = 350 and t...Unsteady flows in a channel with oblique plates have been numerically investigated. The oblique plates as disturbance promoters are installed at the upper wall. Unsteady characteristics are examined for Re = 350 and the plate angles of a = 60。- 120。. The flow fields represent three-dimensional features variously as the plate angle varies. From frequency analysis, it is noted that the disturbed flow by the oblique plates has peculiar unsteady modes. As the flow is more unstable, multiple frequencies are appeared.展开更多
文摘Flow structure and mixing properties by the baffle shape are numerically studied for a baffled micro combustor. The baffle shape is changed by various fuel and hole sizes. The numerical simulations based on different geometric conditions are performed by using the Reynolds Stress Model. The fuel-air mixing is greatly affected by flow recirculations. The centrally located flow recirculation has an important role for the entire mixing performance. The results show that this feature depends on the baffle configurations, and the baffle with small air holes represents efficient characters.
文摘Turbulent jet flows with noncircular nozzle inlet are investigated by using a Reynolds Stress Model. In order to analyze the effects of noncircular inlet, the cross section of inlet are selected as circular, square, and equilateral triangular shape. The jet half-width, vorticity thickness, and developments of the secondary flow are presented. From the result, it is confirmed that the secondary flows of square and equilateral triangular nozzle are more vigorous than that of the circular jet. This development of secondary flows is closely related to the variations of vortical motions in axial and azimuthal directions.
文摘Flow and heat transfer characteristics of a channel with oblique plates which are mounted periodically on the channel wall have been numerically investigated in a laminar range. The main objective of the present study is to find the effect of the tilt angle of oblique plate on pressure drop and heat transfer characteristics in unsteady states. To get the different conditions of the heat transfer and flow evolution, two key parameters of the Reynolds number and the tilt angle of oblique plate are considered. At Re=200,600 , the tilt angles are changed for the range of 50°- 130°. The computational results show that the heat transfer and pressure drop are strongly dependent on the tile angle and Reynolds number. When the flows are unsteady, the tilt angle has an important role in the heat transfer enhancement. Oscillatory structures induce the better mixing of the thermal field and promote the wall heat transfer. For a constant plate length, the wall heat trans- fer is maximized near the 90°- 100°. This is strongly coupled with the variations of flow mixing induced by the oblique plate.
文摘Unsteady flows in a channel with oblique plates have been numerically investigated. The oblique plates as disturbance promoters are installed at the upper wall. Unsteady characteristics are examined for Re = 350 and the plate angles of a = 60。- 120。. The flow fields represent three-dimensional features variously as the plate angle varies. From frequency analysis, it is noted that the disturbed flow by the oblique plates has peculiar unsteady modes. As the flow is more unstable, multiple frequencies are appeared.
