Search Results

Racing engines are required to be developed quickly in order to adapt to ever-changing regulations. A CFD-based optimization would be a useful tool to discover the best solution given the restrictions of the regulations. However, a CFD approach requires repeated trials and errors until the best solution is found because the numerical goal is unknown and the specifications required for the goal are never calculated back when using CFD. Therefore, this paper proposes an Empirically Integrated CFD Method. It is a combination of a one-dimensional CFD and several empirical equations that are derived from the racing engine database with physical meanings. These empirical equations give the CFD-based optimization a proper goal and primary specifications so as to make the optimization loop converge rapidly. This method is experimentally verified for its practical application with a prototype engine.

Larger outboard motors are usually equipped with “power trim and tilt” mechanism (referred to as “FIT”). The mechanism plays an important role to attain good performance and proper function of the craft. (See Fig. 1) Basically, PTT has not been evolved out of its original configuration for 15 years or so. It consists of three hydraulic cylinders positioned in parallel; one of them is used for tilting, and other two for trimming. In recent years, however, the outboard motor market had a strong demand for PTT on mid and small size outboard motors. Such, demand necessitated a new type of PTT that is more compact and less expensive than conventional PTT, and still retains equivalent function and performance. This paper describes first-in-industry coaxial double cylinder PTT (referred to as SPTT; abbreviation of Single-cylinder Power Trim and Tilt), especially focusing on its unique design and layout.