Oil jet lubrication performance directly influences the operation, reliability and fatigue life of meshing gears working under high-speed and heavy-load conditions in the main reducer of rotorcraft. An oil-air two-phase mixture flow numerical simulation model for jet lubrication on the surface of a pair of meshing gears was established by the computational fluid dynamics (CFD) simulation code ANSYS/FLUENT. The effects of the spin flow caused by a high-speed rotating gear pair on the jet flow trajectory deviation were considered in the numerical simulation. The oil volume and oil pressure distribution characteristics of the meshing area were obtained and compared according to different nozzle position layouts, and the optimal nozzle position layout was determined to obtain a maximum oil volume and oil pressure. A gear-jet-lubrication experimental system was built in which the meshing surface temperatures were measured by an infrared thermometer; meanwhile, the jet flow trajectories were photographed by a high-speed camera. The experimental and numerical simulation results were mutually validated and proved the proposed optimal design scheme for the nozzle position layout.

The intermittent pumping technique is often used in the low-permeability reservoir with poor deliverability. In this case, bottom-hole pressure fluctuates periodically and welltest theory in the situation of continuous pumping production is not suitable for intermittent pumping case, due to neglecting pressure buildup per cycle. So it is now necessary to study bottom hole pressure variation regularity of an intermittent pumping well and its welltest interpretation method. First, considering threshold pressure gradient and effects of wellbore storage and skin, mathematical models of intermittent pumping wells for non-Darcy flow at low velocity are established, and mathematical models are solved by using finite element method. Then corresponding type curves are drawn and effects of wellbore storage and skin, mobility ratios and threshold pressure gradients are analyzed.

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