CFD Investigation into Flow Characteristics of a Special Splash Lubrication in Light Helicopters

Abstract

Lubricating oil flow characteristics are the primary concern in the main reducer of light helicopters. To improve the lubricating performance of the main reducer, a special lubrication system is innovatively constructed by adding two oil-guiding tubes to the hub of the output gear, and the influence of the oil-guiding tubes is investigated through CFD (computational fluid dynamics) techniques. A CFD model of the gearbox integrated with the VOF (volume of fluid) technique was established to explore the flow characteristics of the oil–air two-phase flow inside the gearing system. To validate the proposed CFD model, a specialized testing rig is devised and manufactured to examine the features of oil distribution. The effects of the structure parameters of the oil-guiding tubes and operating conditions on the lubrication performance are explored. Comparing experimental and numerical findings reveals that the inner diameter of the oil-guiding tube and the rotational speed of the driven gear have a significant influence on the lubrication performance. In contrast, the length of the installation end of the oil-guiding tube, its angle, and the oil-immersion depth show little impact.

Keywords

• light helicopter
• oil-guiding tube
• splash lubrication
• computational fluid dynamics