The objective of this article is a numerical analysis of the temperature distributions around the notches of a spool valve, because of the viscous heating effect caused by high-speed flow of the large-viscosity hydraulic oil. Two valve spools fabricated with different shapes of notches are investigated, of which spool A is an earlier one, being reported to cause a jam fault under specific working conditions. Spool B is an improved one, which has shown no evidence of damage from jamming in applications up to the present. However, except for practical application, no experimental or numerical tests have been carried out to support it. The deformation of the spool caused by viscous heating is very small, so it is difficult to be observed by conventional experimental methods. In this article, a numerical method is employed to uncover the flow field inside the valve as well as the temperature distributions on the valve spool. The results show important differences between spool A and spool B, including local temperature distributions and peak temperatures around the notches. In conclusion, spool B is evaluated to be more reliable from jam faults than spool A. However, present studies are limited to computational fluid dynamics analysis, which restricts studies on flow and heat transfer. More reliable predictions will be made in the future. [PUBLICATION ABSTRACT]
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