non-newtonian cfd modelling of a valve for mud pumps

Mud pumps, like those used in the field of oil well drilling, are typically of the reciprocating type and are designed to circulate drilling fluid under high pressure down the drill string and back up the annulus. automatic valves must be applied to the fluid end in order to grant the desired pumping effect. from the engineering point of view, the design of the valve geometry must ensure that the phenomenon of cavitation does not occur and that, during the pumping action, the stiffness of the reaction coil spring is able to avoid reaching the condition of end stroke of the valve. Cavitation consists in the development of vapour cavities in the liquid phase. Inside the cavities, the pressure is relatively low. When subjected to higher pressure, the voids implode and generate an intense shock waves that promote the wear for the components (i.e. valve, valve seat, etc.). a deep understanding of the fluid behaviour is crucial for an effective design. Transient CfD simulations of the valve opening have been performed using a non-Newtonian fluid model able to describe the drilling muds. after a deep literature review, the Herschel-Bulkley model was selected as the most suitable for emulating the drilling mud. With the abovementioned approach, the reaction spring and design the valve seat to avoid premature wear phenomena were properly designed. The simulations have been also done considering a Newtonian fluid behaviour, in order to better understand the importance of considering the non-Newton behaviour for an effective design.