The end-face pressure distribution of screw machinery is the premise of calculating the leakage and dynamic characteristics of shaft seals. Unlike other types of machinery

the pressure distribution on the suction end face of screw machinery is related to the operating parameters and the rotor design parameters. To study the leakage characteristics of the screw mechanical shaft seal

a nonuniform pressure distribution model of the end face and a shaft-seal leakage model were established. The accuracy of the model was verified through comparison with existing experimental data. The pressure distribution on the end face

leakage of the shaft seal under different working pressures

built-in volume ratios

and shaft-seal outlet pressures were studied. The results showed that the pressure on the screw-expander end face was nonuniformly distributed

and the average pressure was far less than the working pressure. The average pressure at the end face and the leakage increased approximately linearly to the working pressure. The average pressure of the end face and leakage decreased with an increase in the built-in volume ratio. When the working pressure was increased from 500 kPa to 800 kPa

the average pressure of the end face increased by 12%

and the leakage increased to 3.8 times that of the original value. When the built-in volume ratio increased from 3 to 5

the average pressure on the end face and the leakage decreased by 7.4% and 50%

respectively. The leakage decreased with increasing labyrinth-seal outlet pressure and reduced more distinctly at higher pressures. When the outlet pressure increased from 100 kPa to 300 kPa

the leakage decreased by 37%.