Investigating the Coupling Effect of High Pressure and Hot Air on External Friction Angle Based on Resistance Reduction Tests on Subsoiling Tillage Tools for Sandy Clay Loam

Abstract

Sandy clay loam has the characteristics of both sand and clay. Because of these characteristics, both frictional resistance and adhesive resistance occur between the soil and tillage tool. The combined effect of the two frictional forces increases the external friction angle between the soil and tillage tool, thus increasing the working resistance. To address this issue, this study investigated the coupling effect of high pressure and hot air on the external friction angle by using a self-developed device to measure the external friction angle. Test results showed that high-pressure air between the soil and tillage tool formed a high-pressure air curtain layer which acted as a lubricant, thereby reducing the external friction angle. The external friction angle decreased as the airflow pressure increased. The reduction in the moisture content of the subsoil to less than 30% by the high-pressure hot air reduced the resistance between the soil and tillage tool. The approach with the high-pressure hot air curtain was verified in tests on a subsoiling shovel; the working resistance of the shovel under high-pressure hot air was reduced by 14.8%, demonstrating that this approach was effective in reducing the working resistance of the shovel.