Friction factor analysis for a nanofluid circulating in a microchannel filled with a homogeneous porous medium

This work presents the numerical solution for different velocity profiles and friction factors on a rectangular porous microchannel fully saturated by the flow of a nanofluid introducing different viscosity models, including one nanofluid density model. The Darcy-Brinkman-Forchheimer equation was used to solve the momentum equation in the porous medium. The results show that the relative density of the fluid, the nanoparticle diameters and their volumetric concentration have a direct influence on the velocity profiles only when the inertial effects caused by the presence of the porous matrix are important. Finally, it was found that only viscosity models that depend on temperature and nanoparticle diameter reduce the friction factor by seventy percent compared to a base fluid without nanoparticles; furthermore, these models show a velocity reduction of even ten percent along the symmetry axis of the microchannel.

A Special Extrusion-shear Manufacturing Method for Magnesium Alloy Rods Based on Finite Element Numerical Simulation and Experimental Verification

To research the influences of process parameters on a special extrusion-shearmanufacture method for magnesium alloy rods, deform-3d software with finite elementsimulations has been used to analyze the material flows of deformed magnesium alloysAZ31B during the extrusion-shear (ES) process, as well as the grain sizes anddistribution of extrusion loads, stresses and strains, and blank temperatures. Temperaturefields, stress fields, strain fields and temperature fields varying with different blankpreheating temperatures, extrusion speed and extrusion ratios were simulated. Influences ofdifferent extrusion conditions and different die structures on microstructures of rods prepared by ES process has been researched. Extrusion forces decrease with the increasing extrusion temperatures, decreasing extrusion ratios, increasing die channel angles and decreasing friction coefficients. The flow velocities of metal in the ES die increase with development of ES process. Increasing the channel angles and reducing the friction factors would increase the outflow velocities of metal, but it has little effect on the uniformity of metal flow. The increase in friction and extrusion speed would increase the temperatures of the ES die. The ES process can prepare finer and more uniform microstructures than those prepared by direct extrusion under the same conditions.

COOLING PERFORMANCE OF ADDITIVELY MANUFACTURED PIN FINS IN STACKED MICROCHANNELS FOR THE INSIDE-OUT CERAMIC TURBINE SHROUD-COOLING RING

The Inside-out ceramic turbine (ICT), a novel microturbine rotor architecture, has an air-cooled ring which keeps its composite rotating structural shroud within operating temperature. The cooling ring must achieve a significant radial temperature gradient with a minimal amount of cooling. The cooling ring is made through additive manufacturing, which opens the design space to tailored cooling geometries. Additively manufactured pin fin heat transfer enhancers are explored in this work to assess whether they hold any significant performance benefit over current rectangular cross-section open channels. Experimental friction factors and Nusselt numbers were determined for small, densely-packed pin fins over an asymmetrical thermal load. Results indicate that pressure loss is similar to what can be expected for additively manufactured pin fins, whereas heat transfer is lower due to the extremely tight streamwise pin spacing, in both in-line and staggered pin configurations. A design study presented in this paper suggests that pin fins are beneficial to an ICT for reducing cooling mass flow rate up to 40 %, against an increase in cooling ring mass of roughly 50%.

Drilling Automation – Benefits of the New Drilling Model

A pilot program for automated directional drilling was implemented as a part of the roll out plan in Norway to drill three dimensional wells in an automated mode, where steering commands were carried out automatically by the automation platform. The rollout plan also targeted the use of remote operations to allow personnel to be relocated from the rig location into remote drilling centers. The goal of the program was to optimize the directional drilling performance by assessing the benefits of automation using the latest rotary steerable system technologies and machine learning smart algorithms to predict and manipulated the BHA performance, as well as the ability to predict the best drilling parameters for hole cleaning. The automation was implemented on three different rigs and the data was compared with the drilling performance from the last two years, with three dimensional wells drilled in the conventional method. The main benefits between drilling wells in the conventional method versus drilling wells with the new drilling automation model include the following. Reduce the overall cost per meter – Improve the rate of penetration – Improve running casings Consistence process adherence – Reduce human errors – Reduce POB without sacrificing lost of technical experience Optimize workforce resources – Allows continuity of service (COVID-19 restrictions) Drilling automation can drill smoother wells by reducing the friction factors and tortuosity. This is translated in direct cost savings per meter and reduction in the overall well delivery time, with the advantage of performing the execution and monitoring of the well performance remotely. This new drilling model open the door of new opportunities, especially for the challenges where the work force resources, and drilling performance is a priority for the operations.

Modelling turbulent heat transfer in rough channels using phenomenological theory

Rough walls are often encountered in industrial heat transfer equipment. Even though it is well known that a rough wall affects velocity fields and thermal fields differently (and therefore also skin friction factors and Stanton or Nusselt numbers), predicting the effect of rough walls on turbulent heat transfer remains difficult. A relation between the scalar spectrum and the Stanton number is derived for channels with both smooth and rough walls. It is shown that the new relation agrees reasonably well with recent DNS experiments for wall roughness sizes of k + < 150 and when Pr = 0.7 − 1.0. Under these conditions, a thermal analogue of Moody’s diagram can be created using the newly developed relation.

Drilling Performance and Data Quality Control with Live Digital Twin

The paper presents a solution to the problem of qualitative determination of actual downhole loads and drilling parameters optimization performed employing a dynamic digital well model. The problem of the surface and downhole sensors data quality is disclosed, a solution for an aggregated data QAQC and achieved results are presented. The implementation of the digital platform and the functionality of the dynamic digital twin allowed us to improve the compliance with desired regimes, enabled ensuring the safety of technological operations, allowed us to speed up decision-making while drilling and well completion and commissioning into production. The digital ecosystem allows to timely respond and control operational parameters, to improve and accurately control ROP while minimizing drilling hazards risks and premature drill bit bits wear. The incorporated dynamic digital twin in real-time allows assuring data quality, analyzing activities efficiency, and defining the optimal drilling parameters. The selection of optimal drilling parameters and an increase in ROP are carried out in real-time, based on the analysis of specific mechanical energy. Quality control of sensors plays a key role in the process of evaluating effective weight to bit and associated loads, and in identifying the current friction factor values exhibited downhole. Further on performed trend analysis of the friction factors and respective changes in key drilling parameters allows to track and prevent critical overloads of the drill string, permits to determine the risks of downhole hazards, enables evaluation of well circulation and conditioning activities efficiency in a given interval – allows reducing invisible NPT and the risks of downhole complications. The introduction of a digital ecosystem and a dynamic digital twin allowed us to bring the well construction management process to the next level. Operational response and the decision-making process has been drastically accelerated and improved. Uncertainties associated with an expert's interpretation of drilling states, and subjectivity in the opinions on the effectiveness of processes were eliminated. The negative effect of the human factor and the resulting invisible nonproductive time was minimized. In a short period, the drilling contractor was able to integrate a single digital platform, improve key performance indicators, and involve the field personnel in the full cycle of the technological process of well construction. Field and office personnel, including the driller, can work in a single digital platform, and regardless of the current operation, do always know the true downhole loads, do see the allowable operating envelope and optimal values of the hook load, surface torque, SPP, flow rate, RPM, weight, and torque on the bit, ROP and tripping speeds. The presented method of assessing the quality of the readings of measuring devices and determining the true WOB allows us to optimize the technological parameters during actual drilling. The calculation of the specific mechanical energy is performed based on effective downhole loads transferred to the drill bit. An abnormal increase in the specific mechanical energy notifies the driller to promptly correct the parameters and restore the efficient drilling process. The friction factors are automatically determined during rotation off bottom and tripping operations. Safe corridors and the operational roadmap are re-evaluated every second and are dynamically updated according to the current state of the wellbore and depths.

Single-Phase and Two-Phase Flow Pressure Drop in a Long Double Helicoidally-Coiled Tube

Single-phase and two-phase frictional pressure drop in horizontally-oriented double helically coiled tubes confined in a cylindrical shell is experimentally studied using an instrumented test loop that represents a prototypical liquified natural gas (LNG) fuel delivery system for internal combustion (IC) engines. Adiabatic experimental data addressing liquid (water) and gas (nitrogen) single-phase flows, as well as two-phase flows (air-water) in the helicoidally coiled tubes are presented. The range of Reynolds numbers for single-phase flow experiments is 2600 to 4800. In two-phase flow experiments the liquid-only and gas-only Reynolds numbers varied in 1030 to 6600 and 1700 to 17700 ranges, respectively. In laminar single-phase flow regime the measured friction factors are in relatively good agreement with well-established correlations. In the turbulent flow regime the measured friction factors are moderately higher than the prediction of well-established published correlations. Two-phase flow frictional pressure drops are compared with some relevant correlations, with poor agreement. The generated experimental data are empirically correlated based on the two-phase flow multiplier concept.

CONVECTION IN SCALED TURBINE INTERNAL COOLING PASSAGES WITH ADDITIVE MANUFACTURING ROUGHNESS

Additive manufacturing processes, such as direct metal laser sintering (DMLS), enable creation of novel turbine cooling internal passages and systems. However, the DMLS method produces a significant and unique surface roughness. Previous work in scaled passages analyzed pressure losses and friction factors associated with the rough surfaces, as well as investigated the velocity profiles and turbulent flow characteristics within the passage. In this study, the heat transfer characteristics of scaled additively manufactured surfaces were measured using infrared (IR) thermography. Roughness panels were CNC machined from plates of aluminum 6061 to create near isothermal roughness elements when heated. Fluid resistance differences between the aluminum roughness panels and roughness panels constructed from ABS plastic using the same roughness patterns from McClain et al. (2020) were investigated. Finally, the overall thermal performance enhancements and friction losses were assessed through calculation of surface averaged &#x93;global thermal performance&#x94; ratios. The global thermal performance characterizations indicate results in-line with those found for traditional commercial roughness and slightly below traditional internal passage convection enhancement methods such as swirl chambers, dimples, and ribs. The passages investigated in this study do not include compressibility effects or the long-wavelength artifacts and channel geometric deviations observed by Wildgoose et al. (2020). However, the results of this study indicate that, based on the roughness augmentation alone, artificial convective cooling enhancers such as turbulators or dimples may still be required for additively manufactured turbine component cooling.