Abstract: Aiming at the speed control problem of the detector in oil pipelines, a new type of discharge speed regulation device is proposed, which consists of a relief valve seat, relief valve core, spring, guide rod, and so on. The mathematical model of the discharge speed regulation device is established by analyzing the force of the detector discharge speed regulation device in the horizontal pipeline. The influence of the radians of the relief valve seat, the distance between the relief valve core and the back end of the detector, and the inlet fluid velocity on the motion state of the detector in the pipeline is studied using numerical simulation methods. The research results show that under the same boundary conditions, when the fluid medium passes through the detector, the pressure difference between the front and back ends of the discharge speed control device, the total head loss coefficient, and the turbulent kinetic energy value of the flow field are inversely proportional to the left radian of the relief valve seat and directly proportional to the right radian. When the left radian of the relief valve seat is 60° and the right radian is 15°, all parameters are at their minimum values. An increase in the inlet fluid velocity will lead to an increase in the pressure difference between the front and back ends of the discharge speed regulation device, as well as an increase in the turbulent kinetic energy value of the flow field. When the radians of the relief valve seat is the same and the inlet fluid velocity increases from 0.6 m/s to 2 m/s, the pressure difference increases by 106290 Pa and the turbulent kinetic energy increases by 1.831 m2 /s2 . The distance between the relief valve core and the back end of the detector is inversely proportional to the pressure difference between the front and back ends of the discharge speed regulation device and the speed of the detector. When the distance between the valve core and the back end of the detector increases from 15 mm to 35 mm, the pressure difference between the front and back ends of the discharge speed regulation device decreases by 240 Pa. This study provides an important theoretical basis and practical guidance for optimizing the operational performance of the detector in oil pipelines and improving detection efficiency.

Key words: oil pipeline, internal detector, discharge speed regulation device, differential pressure, speed control