Abstract: An experimental research was conducted on orthogonally rotating rectangular ducts with staggered pin fin array and radial outward throughflow,to determine the effects of the duct tip end ejection area ratio and installation angle on the heat transfer of the duct.In order to study the effect of ejection area ratio (the ratio of the tip end ejection area A 0 to the area of the cross section of the duct A) three models were used with A 0/A equal to 0.067,0.38 and 1.0 respectively.For the investigation of the effect of installation angle α,two models with α equal to 0 and 20 degree were tested.The effects of Reynolds number Re,rotation number Ro and other relevant parameters on heat transfer were also investigated.