简介:AsimilarityequationforheattransferonheatsourceelementssituatedintheentranceregioninelectronicequipmentisdevelopedbasedontheexperimentaldataobtainedbySparrowetal.^[4].ThecharacteristicofthesimilarityequationisthattheratiooftheheattransfercoefficientattheentranceregiontothatatthefullydevelopedregionisindependentoftheReynoldsnumber.Itdependsonlyontherownumberoftheelementssituatedintheentranceregion.Anexampleoftheusefulnessofthesimilarityequationispresentedthatdeterminestheheattransferonheatsourceelementsinapowerunitthatcontainsonlyasmallnumberoftheheatsourceelements.