Adjustable Energy Saving Devices for Transom Stern Hulls
Abstract
We propose a numerical and experimental investigation about the hydrodynamic characteristics oftransom mounted adjustable devices (e.g. interceptors or flaps) on naval vessels, in order to assesstheir potential of propulsion power reduction in a wide range of speeds. Several types of sternappendages have been introduced in the last decade to reduce the resistance of transom stern ships:some of the most interesting for application on naval ships are interceptors and flaps or trim tabs.The study will be aimed to design stern devices with optimal efficiency not only at top speed, butalso cruising/transfer speeds, by a simple (from a construction and operational standpoint)regulation of its variable geometrical characteristics. It capitalizes on the design experience thatthe proposer has acquired in the design of large fast displacement naval vessels as well as on yearsof previous research on the interceptors for high speed planing crafts, using unsteady ReynoldsAveraged Navier Stokes Equations (RANSE) solvers.High and medium fidelity numerical models will be developed and validated for the prediction ofthe longitudinal dynamic equilibrium at speed and the total resistance characteristics of the hull atdifferent interceptor settings. A potential flow panel method with viscous correction will beadapted to study the effect of the stern appendages, as a medium fidelity solver. A volume of fluidUnsteady RANSE solver, with finite volume of fluid to solve for non-linear free surface flows,will be used as high fidelity method.An innovative multi-fidelity design optimization framework, integrating both CFD methods willbe developed and used to design the optimal geometrical characteristics of the stern appendage, inorder to minimize the effective power requested by the reference hull in a wide range of speeds.The optimization procedure will be based on a set of high-fidelity dynamically-refined responsesurfaces (obtained with the multi-fidelity framework) that describe the hydrodynamic forcesdeveloped by the stern appendage with a variation of its geometrical.Numerical results obtained for the final optimal design will be validated by a set of experimentaltests in towing tank, where we will measure pressure distribution on the bottom upstream of theinterceptor at different speeds.Main products: understanding of the hydrodynamics of transom sterns and transom sternappendages for resistance reduction in high speed displacement hull forms; new high fidelity andmedium fidelity simulation models for such flows with relative uncertainty quantification; newstern device that can be potentially applied to hundreds of US Navy vessels new or existing (as aretrofit) to reduce annual fuel consumption.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2017
- Source ID
- N000141712347
Entities
People
- Stefano Brizzolara
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech