Ultrasonic-based measurement of oil film thickness in the valve plate pair of an aviation fuel piston pump

•A method for identifying target echoes on grooved textured surfaces is proposed.•Temperature compensation methods for spring models are investigated.•The oil film thickness distribution of the valve plate pair in AFPP is revealed. The valve plate pairs as a critical component in the Aviation Fuel Piston Pump (AFPP) and often works under heavy loads and high temperatures. It is highly susceptible to oil film rupture, yet its thickness remains imperceptible in an actual pump. This study addresses this issue using an ultrasonic method, overcoming two main challenges: the complicated echo from grooved surfaces and the thermal compensation of the measurement model. Experiments are performed in an AFPP under variable working conditions. The results show that the oil film thickness of about 1–3 μm in the oil intake zone and 2–10 μm in the oil discharge zone is measured, together with the non-planar oil film distribution, indicating that an elastic deformation occurred on the valve plate pair. Furthermore, the oil film thickness in the two zones has different trends with working conditions. These discoveries offer new insights for the design of the AFPP.