Simulation study on characteristic of helicopter nacelle ventilation system in forward flight

Outflow field of helicopter has great effect on air flow of the inlet, the inside of nacelle and exhaust mixer as well as the Characteristics of nacelle cooling system in forward flight. Under the assumption that the size of the exhaust ejector is fixed, a simulation model of the Characteristics of helicopter nacelle cooling system in forward flight is established by considering the combination of the outflow field and exhaust ej ector. To obtain precise calculation results, finite volume method and fully implicit method with coupling multi-grid solving technology are adopted in CFD software simulatioa By the comparison and analysis of calculation results, it is showed that augmenting the size of inlet or putting inlet in the upper front of the nacelle could improve the performance of nacelle cooling system. And by setting the deflector cone in exhaust mixer, not only the velocity of air flow increases, but also the uniformity of exhaust mixer's cross section is improved, which results in the decrease of temperature in the exhaust mixer and the improvement of the efficiency of the cooling system. The conclusions could be used as a reference for designing of nacelle cooling system.