Research on the Pressure Drop Signal Characterizations in Aero-Engine Scavenge Pipe

The pressure drop signal is a key parameter in the study of scavenge pipes. This work systematically investigates the characteristics of a vertical downward scavenge pipe with a 14 mm diameter, using an experimental setup covering oil flow rates of 0.58–9.24 L/min and air flow rates of 0.92–282.08 L/min. A total of 135 pressure drop data sets were collected. The analysis focuses on temporal stationarity, time-averaged values, and frequency-domain characteristics. Results indicate that all pressure drop signals achieved stationarity within 5 s. The time-averaged pressure drop exhibited different trends: at low oil flow rates, it increased slowly at first and then rapidly as air flow rose; at high oil flow rates, the increase was rapid initially, then slowed down. A potential logarithmic relationship between average pressure drop and air flow rate was identified. For most conditions, the fluctuation energy of the pressure drop signal was concentrated below 20 Hz. Although the power spectral density curves showed similar trends under various conditions, their peak values varied significantly, reflecting differences in signal energy. These findings provide important reference value for signal processing and pressure drop prediction in scavenge pipes.