Axial Temperature Research Articles

Connective and magnetic effects in a curved wavy channel with nanoparticles under different waveforms

Abstract The present study describes the peristaltic flow of Jeffrey fluid with nanomaterial bounded under peristaltic waves in a curved channel. Silver (Ag) is the nanomaterial used for this purpose, and base fluid is water. The diversity of peristaltic waves is captured under four different wave profiles traveling along the curved channel. The consequences of heat generation and mass concentration are also taken. The problem is modeled under physical laws and then simplified using the lubrication technique. The obtained system is sketched in graphs directly using a numerical scheme. The physical outcomes of involved parameters on axial velocity, temperature variation, concentration profile, and streamline patterns are discussed in the last section.

Effect of Rayleigh number on transport of solute in a hydromagnetic natural convective flow through a vertical channel with chemical reaction

In the present research, the transport of solute in a hydromagnetic natural convective flow through a vertical channel under the impact of bulk chemical reaction is investigated for the first time using Mei's multi-scale homogenization method. The purpose of this research is to obtain an analytical solution of a physical model for a vertical flow. A uniformly variable axial temperature is considered at both walls. Analytical expressions of Taylor dispersivity, multi-dimensional concentration distributions i.e. horizontal concentration, vertical mean and real concentration distributions are obtained together in the present article. One of the major fact of the present study is to highlight the influence of Rayleigh number (Ra) on mass transfer phenomena in the above mentioned flow. It is observed that both the velocity and Taylor dispersivity reduce due to the increment of the Hartmann and Rayleigh numbers. The Rayleigh number imposes the horizontal uniformity throughout the vertical channel and with the increment of Ra, the variation of horizontal distribution of concentration reduces but it remains tri-modal. It is important to note that, when the Rayleigh number reaches to 275, the non-uniform variation of horizontal concentration distribution becomes bimodal. It is significant to note that a critical value of the Rayleigh number is suggested where the horizontal variation curve becomes bimodal from tri-modal. The outcomes of this study may have a wide range of industrial applications, including metal casting, crystal growth and liquid metal cooling blankets for fusion reactors.

Electro-osmotic transport of a Williamson fluid within a ciliated microchannel with heat transfer analysis

A novel theoretical model is devised for electro osmotic flow of Williamson fluid model by incorporating heat transfer phenomena in a micro ciliated channel. The physical fluid model is designed by exploiting the renowned Debye–Huckel, long wavelength small Reynolds number approximation. The exact expression for Poisson–Boltzmann equation is obtained to find the analytical solution for axial velocity, pressure gradient, temperature and stream functions comprehensively by using perturbation technique. Whereas, transverse velocity and pressure rise profile are explored numerically through the MATHEMATICA software infrastructure. The variations of paramount significant parameters on the velocity distribution, temperature, pressure gradient and pressure rise per wavelength are demonstrated graphically. It has been investigated that axial velocity profiles escalates with enhancing Weissenberg, electro-osmotic, mobility of medium parameter, while dual behavior is recorded for the case of traverse component of velocity. Cilia plays a crucial role in ductus efferentes and assumed to transfer sperm through the rete testis to the epididymis. Besides above mentioned application cilia like actuators serve in micro-mixers to regulate the flow in bio-sensors and in various drug-delivery mechanism.

Thermo-fluid dynamics and synergistic enhancement of heat transfer by interaction between Taylor-Couette flow and heat convection.

This study experimentally and numerically investigated the thermo-fluid dynamics of Taylor-Couette flow with an axial temperature gradient from the chemical engineering perspective. A Taylor-Couette apparatus with a jacket vertically divided into two parts was used in the experiments. Based on the flow visualization and temperature measurement for glycerol aqueous solutions with various concentrations, the flow pattern was classified into six modes: heat convection dominant mode (Case I), heat convection-Taylor vortex flow alternate mode (Case II), Taylor vortex flow dominant mode (Case III), fluctuation maintaining Taylor cell structure mode (Case IV), segregation between Couette flow and Taylor vortex flow mode (Case V) and upward motion mode (Case VI). These flow modes weremapped in terms of the Reynolds and Grashof numbers. Cases II, IV, V and VI are regarded as transition flow patterns between Case I and Case III, depending on the concentration. In addition, numerical simulations showed that in Case II, heat transfer was enhanced when the Taylor-Couette flow was altered by heat convection. Moreover, the average Nusselt number with the alternate flow was higher than that with the stable Taylor vortex flow. Thus, the interaction between heat convection and Taylor-Couette flow is an effective tool to enhance heat transfer. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (Part 2)'.

Mechanical behaviors of coal surrounding horizontal wellbore during drilling process considering the effects of loading rate, pore pressure and temperature

Coal is a kind of rock with the characteristics of soft structure, developed joints, cleats, cracks, and pores, resulting in that its mechanical behaviors are highly sensitive to stress, pore coalbed methane (CBM, gas) pressure and temperature. Thus, due to the variations in stress, pore pressure and temperature caused by the drilling operation, the coal surrounding wellbore can be easily damaged, which would cause serious wellbore instability problems. In this presented work, a stress path of loading axial stress and unloading confining pressure (LAS-UCP) was first determined based on the stress redistribution of the coal surrounding horizontal wellbore in CBM reservoir during drilling process. A series of triaxial compression tests with the LAS-UCP stress path was then conducted to study the effects of axial loading rate, pore pressure and temperature on the mechanical behaviors of coal. The results show that: (1) Under the LAS-UCP stress path, the deformation of coal can be divided into elastic deformation stage, plastic deformation stage, and stress reduction stage. With the decrease in axial loading rate and the increases in pore pressure and temperature, the elastic deformation stage becomes shorter, the plastic deformation stage becomes more significant, stress reduction rate in the stress reduction stage becomes slower, and the coal shows more features of plasticity and ductility. (2) With the increasing axial loading rate, the compressive strength and apparent elastic modulus increase linearly, the absolute values of axial strain, radial strain and volumetric strain at peak stress grow gradually, but the apparent Poisson’s ratio changes irregular. (3) With the increase in pore pressure, the compressive strength, axial strain at peak stress and apparent elastic modulus decrease linearly, the radial strain and volumetric strain at peak stress have no change rule, and the apparent Poisson’s ratio increases gradually. (4) With the increasing temperature, the compressive strength, axial strain at peak stress and apparent elastic modulus reduce gradually, but the absolute values of radial strain and volumetric strain at peak stress, and the apparent Poisson’s ratio increase linearly. The results can not only provide a guidance for safety drilling operation of the horizontal wellbore in CBM reservoir, but also have important significance for other engineering constructions related to coal seam.

Study on the downhole measurement method of weight on bit with a near-bit measurement tool

The downhole weight on bit (DWOB) measurement method using a near-bit measurement tool can directly measure the force between the well bottom and drilling bit, which is crucial for safe and efficient drilling. However, its accuracy is highly influenced by the downhole drilling fluid pressure and temperature difference between the inner and outer walls. Previous studies have proposed compensatory methods. However, these methods are either extremely complex or not sufficiently accurate. In this study, we proposed a DWOB measurement method based on the force-strain principle. We theoretically and quantitatively studied the impact of various factors, including fluid pressure and temperature difference, on strain measurements. The results showed that the strain output is linear with respect to axial force, fluid pressure, and temperature difference. Using this linear relationship, we determined the downhole axial force. Subsequently, we combined the linear relationship with that between the DWOB and obtained axial force and derived a final DWOB measurement equation that incorporated the nozzle jet force, flow friction force, and lift force. Finally, we quantified the three forces using drilling-fluid mechanics and applied the proposed method to both a finite-element simulation and a real-field drilling experiment. The calculated DWOB measurement error in the simulation and field experiment was less than ±1000 N and ±5000 N, respectively. In short, the proposed method may be used to achieve improved WOB measurements and can significantly improve the bit life and increase the rate of penetration (ROP).

Study on the Hierarchical Predictive Control of Semiconductor Silicon Single Crystal Quality Based on the Soft Sensor Model

Silicon single crystal (SSC) quality monitoring and control has been a hot research topic in the field of the Czochralski crystal growth process. Considering that the traditional SSC control method ignores the crystal quality factor, this paper proposes a hierarchical predictive control strategy based on a soft sensor model for online control of SSC diameter and crystal quality. First, the proposed control strategy considers the V/G variable (V is the crystal pulling rate, and G is the axial temperature gradient at the solid-liquid interface), a factor related to crystal quality. Aiming at the problem that the V/G variable is difficult to measure directly, a soft sensor model based on SAE-RF is established to realize the online monitoring of the V/G variable and then complete hierarchical prediction control of SSC quality. Second, in the hierarchical control process, PID control of the inner layer is used to quickly stabilize the system. Model predictive control (MPC) of the outer layer is used to handle system constraints and enhance the control performance of the inner layer. In addition, the SAE-RF-based soft sensor model is used to monitor the crystal quality V/G variable online, thereby ensuring that the output of the controlled system meets the desired crystal diameter and V/G requirements. Finally, based on the industrial data of the actual Czochralski SSC growth process, the effectiveness of the proposed crystal quality hierarchical predictive control method is verified.

Numerical Simulation of Wall Condensation from a Superheated Steam and Air Mixture in a Vertical Pipe

The objective of this study was to evaluate the effects of superheat on wall condensation from a steam and air mixture. We previously measured the radial and axial temperature profiles of a superheated steam-air mixture in a vertical pipe with a diameter of 49.5 mm and a cooling height of 610 mm. In this study, we carried out a numerical simulation for the previous measurements by using the computational fluid dynamics (CFD) code FLUENT, and evaluated the profiles of the mixture temperature Tg and steam mass fraction Xs. The profiles of Tg and the saturated temperature Ts obtained from Xs agreed well with those measured with superheated and saturated conditions, respectively. The validity of the correlation to evaluate a condensation heat flux qc (which was based on the gradient of Xs) was confirmed. Profiles of the dimensionless velocity u+, temperature T+, and steam mass fraction Ys + were obtained, and they were compared with wall functions (i.e., the linear function for a viscous sublayer and the logarithmic law for a turbulent layer). The computed profile agreed with the wall function for u+, agreed relatively well with the wall function for T+, and agreed well with the correlation for Ys + obtained from data measured with saturated steam-air conditions in the region of the turbulent layer.

Impact of Inclined Magnetic Force on Bio-Fluid in Permeable Bifurcated Arteries: Analytical Approach

The present article aims at presenting analytical solutions of the effects of chemical reaction and inclined magnetic force on blood flow through bifurcated arteries placed in a porous medium in association with heat source. The equations of the blood flow model are solved analytically by means of infinite series solution of convergent scheme with appropriate initial and boundary conditions. The important characteristics of the electromagnetohydrodynamic flow of bio-fluid through bifurcated arteries are distinctly highlighted by virtue of the dual solutions that are obtained for Axial velocity, Normal velocity, fluid Temperature, molar species, Skin-friction, Nusselt Number and Sherwood Number. The behaviour of the biofluid variables with individual parameters like Prandtl Number (Pr), Magnetic drag force (Md), Porosity (Kp), Heat source (Hs), Schmidt Number (Sc), Thermal Radiation (R), Chemical reaction rate (Cr), decay (ξ) are discussed in detail through graphs using MATLAB Software. Validation of this work is presented and found suitable. It is disclosed that the flow of bio-fluid is noticeably influenced by the adequate strength of externally applied inclined magnetic force and porosity. This study is essentially important in simple flow, peristaltic flow, pulsatile flow and drug delivery.

Use of electrocautery devices for suture passage through the greater tuberosity: a biomechanical study.

The use of electrocautery to facilitate passage of a suture needle through bone without the aid of a drill or burr is a novel technique that has potential utility in orthopedic procedures, but there is a scarcity of research to support its utility. The specific aims of this cadaveric biomechanical study were to evaluate (1) the axial force reduction during suture passage using electrocautery when applied to rotator cuff repair, (2) the temperature change caused while using electrocautery, and (3) the failure loads and failure modes of this technique. Five matched pairs of fresh frozen humeri were used, classified into 2 groups: with electrocautery on needle (study group) and without electrocautery on needle (control group). Four individual osseous tunnels were made on the greater tuberosity around the insertion of the supraspinatus tendon. Each specimen was sequentially tested in 2 parts: a needle penetration test (part I) to measure the peak axial force and temperature change and a single load-to-failure test (part II) to measure the maximum load to failure as well as the mechanism of failure. A No. 2 FiberWire suture with a straight needle was used. In part I, the mean peak axial force was lower in the study group compared with the control group for all osseous tunnels but was not statistically significant for individual tunnels. However, there was a significant decrease in peak axial force in the study group of 36% compared with the control group overall (P=.033). There was no significant change in temperature of the tunnel site with the use of electrocautery (mean: 0.2±0.3°C, P=.435). In part II, 100% of the samples from each study group experienced bone tunnel failure. Forty percent of the trials in the study group found lower ultimate failure loads compared with the control group (reduction range: 7%-38%). There was no statistically significant difference in the ultimate failure load between either the loop tested or between the 2 study groups (loop 1: P=.352; loop 2: P=.270). Suture passage using electrocautery does significantly decrease the peak force needed to pass a needle directly through the greater tuberosity. This technique does not appear to burn the bone or weaken the bone tunnels. This technique may be useful during open rotator cuff repair or shoulder arthroplasty, although clinicians should be cautious when using this technique as its utility depends on bone quality and cortical thickness, and invivo results may differ.

Effect of Overhead Line Broken Strand Fault on Axial Temperature Decay Distance Under Natural Convection

The broken strand fault of overhead transmission lines will cause a local temperature rise. The temperature extreme value point will decay to the normal area, affecting the operation of adjacent lines. In order to study the relationship between the temperature decay distance, the number of broken strands, and the load current of overhead lines under natural convection, a type LGJ-240/30 line is selected as the test object. Destructive thermal cycling tests are performed in the laboratory. The temperature distribution of the outer surface of the line at the fault area is obtained. Based on the theory of heat transfer, the definition of axial temperature decay distance is proposed, and the relationship between the defined distance and each factor is analyzed. The results indicate that axial temperature decay distance is only negatively related to the load current but not to the number of broken strands. This conclusion provides a theoretical reference for fault identification and maintenance of overhead lines.

Numerical Study of Turbulent Swirling Diffusion Flame Under Lean and Rich Conditions Using Turbulence Realizable k-epsilon Model

ABSTRACT This work investigates numerically a non-premixed swirling flame in a coaxial burner with a radial fuel injection under lean and rich conditions of mixtures. The swirler is placed in the annular part of the burner. The fuel is injected radially through eight holes symmetrically distributed on the periphery of the central tube. All simulations are carried out using the ANSYS-Fluent CFD code. The turbulence is captured using the Reynolds Averaged Navier-Stokes approach. Chemistry/turbulence interaction is resolved using the Eddy Dissipation Model. Simulations are performed with a global equivalence ratio ranging from 0.5 to 1.3. Model validation is achieved by comparing computed results to our experimental data of Stereoscopic Particle Image Velocimetry obtained in the case of the stoichiometric regime. Good agreement between numerical results and experimental measurements is assigned. The central recirculation zone and the swirling jet region due to the presence of the swirl are well predicted by the simulations. The effect of the global equivalence ratio on the profile of axial velocity, temperature distributions and pollutant emissions (CO and NOx) is numerically studied. From dynamic point of view, the equivalence ratio modifies the mean axial velocity of the swirling diffusion flame. The increase of equivalence ratio destabilizes the flame by increasing the liftoff height. NO production decreases by the increasing of the equivalence ratio.

Pipeline leak jet fire thermal characteristic induced by hydrogen-blended natural gas: Physical modeling of temperature profile based on virtual origin theory

Hydrogen-blended natural gas has widely used in energy fuel systems in industrial and domestic applications. During storage, transportation and usage of the fuel, temperature characteristics make a key contribution to energy leak gas fire accidents. In this manuscript experimentally, the buoyant turbulent diffusion axial temperature profile of a hydrogenated methane jet fire is experimentally investigated under free fire and wall fire. Different hydrogen addition ratios, nozzle diameters, and fire heat release rates were considered in the experimental conditions. Temperature profiles and virtual origins were recorded and analyzed. It is found that the wall fire temperature is somewhat higher than that in the free fire at a fixed height. And the vertical temperature of the jet fire increases with the increase of the hydrogen addition ratio, while the flame height decreases. With the addition of hydrogen, the virtual origin is increased, and virtual origin of wall fire is clearly larger than that of the free fire. Due to the restriction of air entrainment from the sidewall and the hydrogen addition, the physical mechanism of restricted air entrainment was analyzed. In addition, a non-dimensional model of the virtual origin was proposed and analyzed for different conditions. Finally, the normalized vertical temperature profile in the continuous flame region, intermittent flame region and buoyant plume region based on the virtual origin and mirror-approach are still well characterized for air entrainment under all conditions. The results of this paper may demonstrate the potential for the risk assessment of hydrogen-blended natural gas fire.

Scale-Dependent Thermomechanical-Forced Noncircular Torsional Vibration of Lipid Supramolecular Nanotubes via Timoshenko–Gere Theory

Dynamic modeling of lipid nanotubes as a drug carrier in the skin layer is important. The displacement fields of lipid nanotubes in the shunt path of the skin layer are considered twisting. The twisting of the lipid nanotube in the skin layer causes the warping of the structure and, as a result, causes normal strain. The normal strain in the strain fields is not considered in the torsional noncircular structures. Therefore, in this study, not only the effect of shear strains but also the effect of normal strain on the torsional vibration of lipid nanotubes are considered based on the Timoshenko–Gere theory for the first time. Also, the temperature can be considered in the modeling due to the normal strain in the torsional of warped structures. Then, the governing equations of the forced torsional vibrations of lipid nanotubes, by considering the general warping function of cross-section, are derived based on the nonlocal strain gradient theory. The governing equation is solved by utilizing the convolution integration, and the dynamic responses of lipid nanotubes in the presence of external nonlinear harmonic moving torque are obtained. In the results, dynamic and frequency responses in the presence of temperature for rectangular and elliptical lipid nanotubes have been analyzed. One of the methods of drug release in nanocarriers is stimulation with ultrasound waves. Therefore, stimulating the lipid nanotubes using ultrasound waves at the obtained frequencies makes it possible to release the drug from the lipid nanotubes. Also, the maximum dynamical response of Timoshenko–Gere torsion is less than typical torsion. Increasing the aspect ratio of cross-section dimensions of lipid nanotubes decreased the maximum dynamical response. Increasing the velocity parameter first increases the dynamical twist and then reduces it. Also, the effects of axial forces and temperature on the maximum dynamical responses and the dynamical twist of the lipid nanotubes are studied. For validation, the obtained results are compared with the results of previous research.

Influences of rotation and mass and heat transfer on MHD peristaltic transport of Casson fluid through inclined plane

In the present analysis, we discussed the influence of heat and mass transfer on the hydro-magnetic peristaltic flow of a Casson fluid in a rotating inclined system through an asymmetric channel. The model governing equations are obtained, simplified by applying long wavelength and assumptions of low Reynolds number, and then addressed analytically. DSolve command of Mathematica software was used to solve these equations. The numerical results regarding the impacts of embedded parameters on axial velocity, secondary velocity, stream function, temperature, concentration, and streamline patterns are graphed and explained. It has been discovered that velocity slip reduces the size of the trapped bolus while the permeability parameter increases it. The velocity and temperature profiles decrease as the Casson fluid parameter and magnetic field strength increase. In the fields of biomedical engineering and crude oil refinement, the current problem is quite significant. The trapping phenomenon for different parameters is presented. The visual discussion of numerical results for various values of relevant physical parameters. The current work, which focuses on electromagnetic peristaltic pumps, offers several applications in biomedical engineering.

Investigation of Conjugate Effects on Forced Convection in Diamond (Diverging–Converging) Microchannels

Abstract A three-dimensional solid–fluid conjugate model is employed to provide physical insights into the effect of wall conduction on fluid convection in a diamond-shaped microchannel. The study covers the effect of divergence-convergence angle, width ratio, thermal conductivity ratio, thickness ratio, and Reynolds number on peripheral heat flux, temperature, and Nusselt number profiles. Isotherms show a multidirectional thermal gradient for low thermal conductivity ratios, whereas only an axial thermal gradient is seen for higher thermal conductivity ratios. Furthermore, the overall axial surface temperature gradients decrease with increasing divergence-convergence angle and decreasing width ratio. The study also shows that the thermal conductivity ratio significantly influences the Nusselt number, while the thickness ratio has only a moderate influence for all geometries. The analysis also reveals that at a particular intermediate thermal conductivity ratio, the Nusselt number becomes maximum. Lastly, a nondimensional wall conduction number is used to characterize conjugate effects in diamond microchannels. The wall conduction effect is inconsequential in diamond microchannels when the nondimensional wall conduction number is less than 0.01. The present study is beneficial from a practical perspective as it helps design the optimum channel geometries subjected to conjugate effects for many heat transfer applications.

Oxy-methane combustion characteristics in a vertical porous plate reactor

Among the carbon capture technologies, oxy-fuel combustion is more competitive in terms of efficiency and cost. However, pure oxygen is required for oxy-combustion, and the oxygen separation from the air by conventional methods is costly and energy-intensive. Ion transport membranes (ITMs) have shown considerable improvement in energy efficiency. The current ITMs suffer from low O2 permeation flux required for practical fuel conversion rates. The experimental and numerical methodologies are not much developed in studying the ITM integrated reactors. Therefore, using a porous medium can give much insight into the technology. Understanding the flow dynamics and combustion properties inside an oxygen transport membranes reactor (OTMR) is of utmost importance to developing efficient systems. Most studies have focused on analyzing face-to-face horizontal porous plate reactor designs. A horizontal reactor’s flame structure and buoyancy effect are substantially different from that of a vertical reactor. Hence, the current study aims to investigate oxy-methane combustion in a vertical face-to-face porous plate reactor to mimic the performance of an OTMR using computational fluid dynamics (CFD). Axial and transverse temperature profiles and species concentration profiles are analyzed concerning the feed inlet flow rates, inlet temperature, and oxidizer ratio in this work. The outlet and maximum temperatures vary from 1,587 K to 1,621 K and 1,751 K to 2,341 K upon increasing the oxidizer ratio from 0.20 to 0.35; correspondingly, it shows that the maximum temperature within the reactor is significantly affected by the oxidizer ratio. In the vertical OTMR, the maximum and outlet temperatures are lowered by 82 K and 53 K, respectively, compared to the horizontal one because of the uniform temperature distribution in the former case. This research will help to improve reactor design for OTMR applications. Further investigations on the flame structure and static flame stability are required for a better understanding and insight into the reactor design.

誘導機の回路モデルにおける軸方向影響とロータ温度の考慮

誘導機の回路モデルにおける軸方向影響とロータ温度の考慮

Numerical investigation of the effects of axial temperature gradient and cooling rate on InGaSb crystal growth under micro-gravity

In order to investigate the transport phenomena, growth mechanism of InGaSb crystal growth under microgravity, and also to optimize future space experiments, two-dimensional axisymmetric numerical simulations were carried out with different axial temperature gradients and cooling rates. Results showed that under microgravity condition both crystal growth process and grown crystal qualities were significantly affected by its axial temperature gradients and cooling rates. Simulation suggested that an axial temperature gradient around 0.6 K/mm with cooling rate of 0.048 K/h can accelerate and optimize the whole dissolution and growth process of InGaSb crystal growth in space, preventing complete dissolution of feed crystals, improving growth rates and grown crystal compositional uniformity.

Continuous-wave-laser surface cleaning of high strength bolts: Analysis of bolt axial force loss

This study examined the axial force loss of high-strength bolts after a 3-kW continuous-wave laser (CWL) treatment. Friction connection specimens with M22 high-strength bolts were prepared, and a fixed-angle rotary CWL transmitter with a 26-mm-diameter laser ring and rotating platform was used for nut rotary cleaning of high-strength bolts. Changes in the axial force and temperature of the bolts were monitored during the laser treatment based on the irradiation duration on the nut surface. The experimental results indicated that the minimum and final stable values of the axial force during CWL treatment are affected by the irradiation duration. Multiple rounds of irradiation can reduce the bolt axial force loss for the same total irradiation duration. The 26-mm-diameter laser ring can sufficiently cover the surface of commonly used bolt heads and nuts in bridges, and the local temperature effect does not influence the axial force loss in adjacent bolts. The distribution of the bolt temperature when the CWL treatment the bolt is simulated by an FE model, which proves the overall temperature of the bolt does not exceed 300 °C and remains in a normal working condition when the continuous irradiation duration is less than 45 s. From the relationship between the axial force change and treatment duration, the axial force loss formula was fitted, which can help provide a maintenance plan for M22 bolt cleaning using 3-kW CWL.