Simulation And Characteristics Of Pumping Ring Flow Field For Mechanical Seals

In order to improve the sealing performance and service life of the mechanical seals and prevent seal failure,it is usually equipped with an auxiliary system.The key component in the system for circulating the sealing liquid is the pumping ring.This paper takes a spiral pumping ring of Sichuan Nikki Seal Co.,Ltd.as the research object,the geometric model and physical model of the spiral pump ring are established,and the internal flow field of the spiral pump ring is numerically simulated by Fluent.The pressure distribution of the pumping ring and the distribution law of the fluid velocity are studied.The influence of the structural parameters and working parameters of the pumping ring on its pumping performance is also studied,the working mechanism and related pumping rules of the spiral pumping ring are revealed,which provides theoretical guidance and basis for the design and research of the spiral pumping ring.The main conclusions drawn are as follows:(1)The pressure distribution of the fluid film in the pumping ring gradually increases along the spiral direction of the spiral groove,and the pressure gradient of the spiral pumping ring is evenly distributed.(2)The fluid flow rate gradually decreases from the spiral groove wall toward the center of the spiral groove,and the fluid has a distinct vortex flow in the center of the spiral groove,and the speed reaches the minimum.(3)The rotational speed of pump ring and the viscosity of sealing fluid have a significant effect on the pumping performance of the pumping ring.Too low a speed will result in a weak pumping capacity of the pumping ring.The general speed should be higher than 2000r/min,and the lift will increase significantly with the increase of the speed of pump ring and the viscosity of sealing fluid.(4)The number of thread heads,groove depth and spiral length of the spiral pumping ring have a certain influence on the pumping performance.Increase the number of thread heads,and the pumping ring lift is first increased and then decreased,reaching the maximum within 10-12 heads,therefore,the number of thread heads is the best in 10-12 heads,with a priority of 12 heads;.Increasing the depth of the pumping ring and the length of the spiral,the lift is increased,but too shallow groove depth and too short spiral length will cause the pumping capacity of the screw pumping ring to be weak.Generally,the pumping ring groove depth should be greater than 2mm.The length of the pumping ring helix should be greater than 20 mm,but as the length of the pumping ring spiral increases,the area with the lowest pressure increases significantly.Therefore,the groove depth is in the range of 3.5-5mm,and the spiral length is optimal in the range of 40-50 mm.(5)The groove width of the pumping ring,the gap between the outer diameter of the pumping ring and the inner diameter of the transition seat has a significant influence on the pumping performance.The groove width of the pumping ring is increased,the lift is obviously increased first and then decreased,and the lift is highest when the groove width is 3.5mm,therefore,the slot width is optimal within 3-4 mm,and the priority value is 3.5mm;.Increase the pumping ring gap,the lift significantly reduced,excessive space can cause the pumping ring to lose pumping capacity.Usually the gap should be less than 1mm,but as the gap decreases,the minimum pressure is significantly reduced.Therefore,the gap is optimal in the range of 0.1-0.3mm.(6)Under different parameters,the change trend of the lift head of the pumping ring decreases with the increase of the flow rate,but with the increase of the speed of pump ring and the viscosity of the sealing liquid,the head changes with the flow is rise,the head has little change with the flow rate as the length of the spiral changes;with the number of threads,the groove width and the groove depth the increase of the head with the change of the flow tends to be gentle;as the gap decreases,the head increases with the change of the flow.