Heat transfer of confined impinging jet onto spherically concave surface with piston cooling application

Heat transfer for confined impinging jet onto spherically concave surface with piston cooling application is investigated. It involves nominal Reynolds number with five different reciprocating frequencies, that resulted in pulsating number which represents the ratio of reciprocating force to inertial force effect, varying from 0 to 1.85E-4. Along the spherically concave heating surface the evolution of flow structure from separation point into laminar and then turbulent annular flows is demonstrated. As the reciprocating force modified the heat transfer from non-reciprocating situation, it needed to account for the effect of reciprocating motion on the heat transfer within the coolant channels of piston to achieve the optimum design of cooling systems.