A parametric study on unbalanced moment of piston type valve core

In this paper,the piston type valve core and the unbalanced moment on its bottom are studied.To decrease the influence of non-common geometrical factors,a simplified model of the piston type globe valve is proposed in this study.Based on the computational fluid dynamics(CFD)method,the effects of different geometrical parameters on the unbalanced moment existing on the bottom of the valve core,which include the bending radius of the inlet flow channel,the diameter of the special-shaped pipe,and the height of the valve core,are studied.Finally,the effects of geometrical parameters on the unbalanced moment on the bottom of the valve core are clarified by correction and variation classification and provide a basis for further optimizing the structure of the piston type valve.The results show that the unbalanced moment decreases with the increase of the bending radius of the inlet flow channel,but increases with the increase of the diameter of the special-shaped pipe and the height of the valve core.Moreover,the relation between the unbalanced moment and flow rate is proposed.

Solid-liquid flow characteristics and sticking-force analysis of valve-core fitting clearance

External contamination particles or wear particles corroded by a valve body are mixed into the fluid. As a result, when the fluid enters the fitting clearance of the valve core, it can cause an increase in resistance and lead to sticking failure of the valve core. This paper analyzes solid-liquid flow characteristics in fitting clearances and valve-core sticking based on the Euler-Euler model, using a typical hydraulic valve as an example. The impact of particle concentration and diameter on flow characteristics and valve-core sticking force was analyzed. The highest volume fraction of particles was in the pressureequalizing groove(PEG), with peak values increasing as the particle diameter increased. The sticking force increased with increasing particle concentration. When the particle diameter was 12 μm, the sticking force was the largest, making this the sensitive particle diameter. Particle distribution and valve-core sticking force were compared for oval, rectangular, and triangular PEGs. The fluid-deflection angles in oval and rectangular PEGs were larger, and their values were 32.83° and 39.15°, respectively. The fluid-deflection angle in the triangular PEG was relatively small, less than 50% that of the oval or rectangular PEGs. The particle-volume-fraction peaks in oval, rectangular, and triangular PEGs were 0.0317, 0.0316, and 0.0312, respectively. The sticking forces of oval, rectangular, and triangular PEGs were 4.796, 4.802, and 4.757 N, respectively when the particle diameter was 12 μm. This work provides a reference for design and research aimed at reducing valve-core sticking.