PERFORMANCE EVALUATION OF SUBMERGENCE RATIO OF A RECTANGULAR SUBMERGED VANE WITH A COLLAR

The vane induced strength of secondary flow in terms of dimensionless moment of momentum is maximum in the case of a rectangular vane with a collar at angle of attack 400 at different degrees of submergence (T/d) such as 0.60, 0.67 and 0.75. The same value of optimal angle of attack was found by Marelius and Sinha (1998) in the case of a rectangular vane without a collar. The vane induced strength of a vortex is insensitive to the submergence ratio (T/d). The vane induced strength of a vortex in terms of moment of momentum (MOM) depends on a wide range of variables, such as angle of attack, vane height, vane length, vane thickness flow depth, water density, median sediment size, velocity vector, acceleration due to gravity, water dynamic viscosity,vane shape, taper angle, etc. The optimal angle of attack is very close to 40°. A dimensionless moment of momentum parameter has also been identified. Vane induced secondary flow is also related to linear momentum. The graphical plot of moment of momentum vs. different angle of attack shows a similar trend as that of the plot of dimensionless MOM such as MOM made nondimensional by flow depth or by vane height vs. angle of attack.