Vladimir Zhigarev

On laminar-turbulent transition in nanofluid flows

The paper presents experimental data on the laminar-turbulent transition in the nanofluid flow in the pipe. The transition in the flows of such fluids is shown to have lower Reynolds numbers than in the base fluid. The degree of the flow destabilization increases with an increase in concentration of nanoparticles and a decrease in their size. On the other hand, in the turbulent flow regime, the presence of particles in the flow leads to the suppression of smallscale turbulent fluctuations. The correlation of the measured viscosity coefficient of considered nanofluids is presented.

An Experimental Study of the Influence of Added Nanoparticles on the Filtration of Microsuspensions via Porous Media

We have experimentally studied the filtration of microsuspensions with added silica (Aerosil) nanoparticles via porous media of variable permeability. The concentration of added nanoparticles in solution was changed from 0.25 to 4 mass % and their average size was varied from 5 to 100 nm. Dependences of the filtration losses of microsuspension on the concentration and size of nanoparticles and the permeability of porous medium variable have been determined.

A Study of the Influence of Nanoparticles on the Properties of Drilling Fluids

The effect of nanoparticles with different compositions and sizes on the rheological properties, filtration losses, and lubricating ability of drilling fluids has been experimentally studied. Nanoparticles of silicon, aluminum, and titanium oxides have been examined, while an aqueous bentonite suspension with a solid phase mass fraction of 5% has been used as a basic model of a drilling fluid. The concentrations and sizes of nanoparticles in the drilling fluids have been varied from 0.25 to 2 wt % and from 5 to 100 nm, respectively. It has been shown that the addition of nanoparticles substantially changes the properties of the drilling fluids. In contrast to suspensions of particles with macro- and microscopic sizes, the rheological parameters, filtration losses, and lubricating and sticking abilities of the suspensions containing nanoparticles depend on the size and nature of the latter and vary markedly already at low nanoparticle concentrations.

Investigation of the additive effect of nanoparticles on the hydrodynamic characteristics of drilling fluids

Investigations of the rheological properties of drilling fluids based on nanoparticles are carried out. The dependences of the effective viscosity and rheological parameters of fluids on the concentration, size and material of nanoparticles, and the physico-chemical properties of the model fluid are obtained. The study results of the filtration of drilling fluids with nanoparticles are obtained. Dependences of filtration characteristics of drilling fluids on concentration, size and material of nanoparticles are obtained.

Investigation of forced convection ZrO2 nanofluid in a channel with artificial roughness

The paper presents the results of experimental study of turbulent forced convection of water-based nanofluid with ZrO2 nanoparticles. Volumetric concentration of the nanoparticles in the experiments was equal to 4%. The average particle size was 105nm. The study was carried out for a smooth round tube and round tube with knurling ring. The effect of additives of ZrO2 nanoparticles on the average heat transfer coefficient and the pressure drop in the channel was investigated. Has been shown that the intensification of heat transfer by using nanofluid weakly dependent on the shape of the channel, and determined only by the properties nanofluid.

Enhancement of long hole drilling efficiency with drilling units with replaceable core tubes

The article presents a procedure to calculate fluid pressure losses in hole drilling with units equipped with replaceable core tubes and using non-Newtonian mud fluids. It is found that main hydraulic loss takes place when mud fluid flows in clearing between a drill string and drill hole walls. Numerical modeling has shown that it is possible to reduce hydraulic pressure loss by 76.5–89.0% by increasing drill string diameter by 2 mm. Based on the analytical research results, diamond drill bits and underreamers with the outer diameters of 78.0 and 78.4 mm, respectively, are manufactured for drilling operations in Talnakh ore field.