A wing-body junction flow of a navigating underwater vehicle is considered to be a crucial source of the flow radiating acoustic noise, which attracts much research interest. In this paper, wing-plate junction flows a...A wing-body junction flow of a navigating underwater vehicle is considered to be a crucial source of the flow radiating acoustic noise, which attracts much research interest. In this paper, wing-plate junction flows are experimentally investigated in a low-speed wind tunnel by smoke-wire flow visualizations and time-resolved PIV measurements. To reveal the physical behavior of such flows, smoke-wire flow visualizations are conducted for a laminar wing-plate junction. A novel control strategy is proposed, to accurately locate the suction openings where the streamline is about to roll up to form a vortex in the turbulent junction flows. The control effect is discussed in perspectives of both the time-averaged and instantaneous flow fields.展开更多
Combining flows often occur in open channel networks of drainage systems and river engineering. Open-channel junction flows were analyzed by solving the depth-averaged two-dimensional, elliptic Reynolds-averaged Navie...Combining flows often occur in open channel networks of drainage systems and river engineering. Open-channel junction flows were analyzed by solving the depth-averaged two-dimensional, elliptic Reynolds-averaged Navier-Stokes equations with the Hanjalic-Launder (H-L) modification to the k-ε turbulence model without the free surface “rigid lid” approximation with an efficient finite-volume procedure. The model can also analyze flows with separation. The model was used to analyze the relative importance of various factors and was compared with laboratory measurements. The H-L modification produced much better simulations of the separation zone size with 20% better accuracy than the standard k-ε model. The H-L modification was then used to study the characteristic of junction flows and the separation zones with different discharge ratios. The simulational results show that separation zone size decreases as the discharge ratio of the upstream main channel to the downstream channel increases.展开更多
The possibility of using a fillet form to control the horseshoe vortex flow caused by the turbulent shear flow around wing-body junction has been investigated numerically. A numerical method for the solution of three ...The possibility of using a fillet form to control the horseshoe vortex flow caused by the turbulent shear flow around wing-body junction has been investigated numerically. A numerical method for the solution of three dimensional incompressible, Reynolds-averaged Navier-Stokes equations with the two-equation (k, ε) turbulence model has been developed to evaluate the effect of fillet forms on appendage-body junction vortex flow. The wing investigated is NACA0020. The Reynolds number based on a chordlength is 1. 0 ×105. Three configurations including a baseline, a triangle fillet form, and a constant radius convex arc fillet form along the entire wing/flat-plate junction are presented. It is shown that a suitable convex filet form can significantly improve the stability of junction horseshoe vortex and reduce the strength of vortex and the non-uniformity in the wake velocity profile. It is also demonstrated the capability of the numerical approach in the design of vortex flow control devices.展开更多
基金Project supported by the National Natural Science Foun-dation of China(Grant No.11102188)the National Key Labo-ratory of Science and Technology on Hydrodynamics
文摘A wing-body junction flow of a navigating underwater vehicle is considered to be a crucial source of the flow radiating acoustic noise, which attracts much research interest. In this paper, wing-plate junction flows are experimentally investigated in a low-speed wind tunnel by smoke-wire flow visualizations and time-resolved PIV measurements. To reveal the physical behavior of such flows, smoke-wire flow visualizations are conducted for a laminar wing-plate junction. A novel control strategy is proposed, to accurately locate the suction openings where the streamline is about to roll up to form a vortex in the turbulent junction flows. The control effect is discussed in perspectives of both the time-averaged and instantaneous flow fields.
文摘Combining flows often occur in open channel networks of drainage systems and river engineering. Open-channel junction flows were analyzed by solving the depth-averaged two-dimensional, elliptic Reynolds-averaged Navier-Stokes equations with the Hanjalic-Launder (H-L) modification to the k-ε turbulence model without the free surface “rigid lid” approximation with an efficient finite-volume procedure. The model can also analyze flows with separation. The model was used to analyze the relative importance of various factors and was compared with laboratory measurements. The H-L modification produced much better simulations of the separation zone size with 20% better accuracy than the standard k-ε model. The H-L modification was then used to study the characteristic of junction flows and the separation zones with different discharge ratios. The simulational results show that separation zone size decreases as the discharge ratio of the upstream main channel to the downstream channel increases.
文摘The possibility of using a fillet form to control the horseshoe vortex flow caused by the turbulent shear flow around wing-body junction has been investigated numerically. A numerical method for the solution of three dimensional incompressible, Reynolds-averaged Navier-Stokes equations with the two-equation (k, ε) turbulence model has been developed to evaluate the effect of fillet forms on appendage-body junction vortex flow. The wing investigated is NACA0020. The Reynolds number based on a chordlength is 1. 0 ×105. Three configurations including a baseline, a triangle fillet form, and a constant radius convex arc fillet form along the entire wing/flat-plate junction are presented. It is shown that a suitable convex filet form can significantly improve the stability of junction horseshoe vortex and reduce the strength of vortex and the non-uniformity in the wake velocity profile. It is also demonstrated the capability of the numerical approach in the design of vortex flow control devices.
