Prediction of Torque Variations in a Pipe Inspection Robot through Computational Fluid Dynamics

Abstract

Several designs of In-pipe inspection robots (IPIR) have been proposed in the literature to solve the problems related with inspection of these complicated internal geometries. Designing of an in-pipe inspection robot (IPIR) is a difficult task and hence the designer must take care of the design issues. Authors have already proposed a new design for in pipe inspection robot. This research work presents investigations into driving torque variation during its use in a full running pipe to overcome the drag caused by the flowing viscous fluid. This proposed model is a screw driver type wall press adaptable wheeled In-pipe inspection robot. It is able to move through vertical, inclined and horizontal pipes and it can easily pass through elbow of a pipe line. This model comprises of three modules- rotor, stator and control unit. The Rotor module has three wheels mounted on the outer periphery with a helix angle of 18°. Wheels of rotor follow the helical path on the internal surface of pipe line and move in the longitudinal direction inside the pipe. A mathematical model is proposed to estimate the driving torque required by the proposed robot. Driving torque is a function of forces coming on the robot due its motion inside the pipe and drag force generated due to flowing media. The torque on motor varies with change in viscosity of flowing fluid inside the pipe, speed of fluid and pipe inclination. The form and skin drag forces are predicted using computational fluid dynamic approach through ANSYS fluent software and robot driving torque variation is studied under full running pipe.