Transient Flow Characteristics of a Pressure Differential Valve with Different Valve Spool Damping Orifice Structures

Abstract

Lubrication system failure is a significant cause of in-flight shutdown incidents in aviation engines. The pressure differential valve, an essential component of a certain type of aviation engine lubrication system, is responsible for controlling the flow rate and pressure of the lubricating oil. Comprehending the transient flow characteristics of the pressure differential valve is of paramount importance for the secure operation of lubrication systems. This paper establishes a transient flow model of a pressure differential valve based on a transient computational fluid dynamics (CFD) method, and the experimental validation demonstrates the effectiveness of the computational model. The internal flow characteristics of the differential pressure valve at different stages during the opening process were studied. Additionally, four transient lubricating oil flow models with different valve spool damping orifice were established to analyse the impact of damping orifice structure on valve spool movement characteristics, pressure control characteristics, and flow field distribution. The results indicate that when the diameter of the valve spool damping orifice increases from 0.3 mm to 1.0 mm, the valve spool displacement and fluid force increase by 88 % and 20 %, respectively. Meanwhile, the peak valve spool velocity, peak oil supply pressure, and steady-state value decreased by 15 %, 29 %, and 34 %, respectively. As the length of the valve spool damping orifice increases from 0.894 mm to 4.0 mm, the growth rate of valve spool displacement and fluid force gradually decreases, with the peak valve spool velocity decreasing by 7 %. This study has potential significance for the structural optimization and application of pressure differential valve in lubrication systems.