出版社：Defence Scientific Information & Documentation Centre
摘要：The hydrodynamic mechanism and parametric influences of the wedge flap and the anti-spray rail in combination is investigates. A methodology with specific guidelines for incorporating these appendages with significant drag reduction is provided. Small crafts designs frequently require interventional changes to realise the desired guaranteed speed with their installed engine power. The appendages namely, the wedge, flap and anti-spray rails are used as retrofit measures or adapted in new hull forms, in isolation or in combination, to improve the drag and bring down the power requirement. A judicious combination of different appendages can result in significantly reduced drag and therefore power saving. The methodology combines the results of numerical and experimental investigations. The systematic study identifies the parameters for control namely, wedge flap size in terms of the chord length, its orientation vide the angle of the wedge flap, and the anti-spray rail location with respect to the water surface. The choice of the size of the wedge flap is a constrained problem since excessive wedge flap can cause problems related to length and hydrodynamic loading. This study establishes a solution by combination of a minimum integrated wedge flap with properly located anti-spray rail to reduce the drag. The study shows favourable influences due to local pressure and numerical results using a RANSE solver show good comparison with experimental test results. The methodology is a new approach towards drag reduction in new designs as well as drag control by retrofit.
