non-newtonian cfd modelling of a valve for mud pumps

Abstract

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.

Research on rheological behavior of fresh concrete single-cylinder pumping based on SPH-DEM

“…Subsequent studies have improved the linear relationship of the Bingham model, making the model retain the original yield stress with the addition of a nonlinear fit 15 , i.e., , which adds a power-law index that allows the model to characterize shear thinning or shear thickening phenomena. The classical computational fluid dynamics (CFD) approach treats concrete as a single fluid phase, ignoring the coarse aggregates, reinforcing fibers and other large scale particles in it, and calculates the concrete mesh flux to obtain the velocity variation and shear deformation region of the concrete flow process 16 . Robin De Schryver et al 17 used OpenFOAM (OpenFOAM Fundation Ltd, incorporated in England) single-phase flow to calculate the pressure of the concrete pumping process, the results are one pressure value higher than the experimental values, which is explained by the fact that concrete undergoes compositional changes during transport in the pumping pipeline, which results in much smaller rheological parameters near the walls than the actual concrete.Secrieru et al 18 and others, using the commercial software Fluent (Ansys Ltd), divided the concrete into two phases, using the rheological parameters of the lubrication layer near the wall and the internal plunger flow using the rheological parameters of the concrete itself for pumping pressure analysis, and the simulation results were very close to the experimental numerical results.…”

Research on Rheological Behavior of Fresh Concrete Single-cylinder Pumping Based on SPH-DEM

“…Subsequent studies have improved the linear relationship of the Bingham model, making the model retain the original yield stress with the addition of a nonlinear fit 15 , i.e., 𝜏 = 𝜏 𝑦 + 𝐾(𝛾)𝛾̇𝑛, which adds a power-law index 𝑛 that allows the model to characterize shear thinning or shear thickening phenomena. The classical computational fluid dynamics (CFD) approach treats concrete as a single fluid phase, ignoring the coarse aggregates, reinforcing fibers and other large scale particles in it, and calculates the concrete mesh flux to obtain the velocity variation and shear deformation region of the concrete flow process 16 .Robin De Schryver et al 17 used OpenFOAM (OpenFOAM Fundation Ltd, incorporated in England) single-phase flow to calculate the pressure of the concrete pumping process, the results are one pressure value higher than the experimental values, which is explained by the fact that concrete undergoes compositional changes during transport in the pumping pipeline, which results in much smaller rheological parameters near the walls than the actual concrete.Secrieru et al 18 and others, using the commercial software Fluent (Ansys Ltd), divided the concrete into two phases, using the rheological parameters of the lubrication layer near the wall and the internal plunger flow using the rheological parameters of the concrete itself for pumping pressure analysis, and the simulation results were very close to the experimental numerical results.…”