Friction Temperature Research Articles

Large eddy simulation of particle hydrodynamic characteristics in a dense gas-particle bubbling fluidized bed

A subgrid scale particle kinetic turbulent energy model coupled with a second order moment model is developed to describe the particle hydrodynamic characteristics in dense gas-particle fluidized bed. Anisotropic behaviors of particle dispersions and interactions between gas and particle are fully revealed by means of two-phase Reynolds stresses transport eqs. A four-way coupling strategy for the consideration of particle-particle collisions is modeled by frictional granular temperature transport equation. Simulation results by large eddy simulation are validated by experimental measurement with acceptable agreement. Heterogenous flow structures, anisotropic characteristics of particle dispersions and wider-size distribution behaviors of bubbles are indicated. At the height of 0.2 m, the largest dominant frequency of porosity is 25.0 Hz at lateral 0.375 cm away from center, it is approximately 5.0 times larger than that of lateral 9.375 cm. Compared to 0.45 m, the standard deviations of 82.5 cm/s at lateral region is approximately 1.5 times larger than that of center region.

Impacts of entropy generation in second-grade fuzzy hybrid nanofluids on exponentially permeable stretching/shrinking surface

The present investigation aims to use entropy analysis to analyze the unsteady Magnetohydrodynamic (MHD) flow in a second-grade fuzzy hybrid Al2O3-Cu/SA\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {{\ ext{Al}}_{{2}} {\ ext{O}}_{{3}} - {\ ext{Cu/SA}}} \\right)$$\\end{document} nanofluid over an exponentially shrinking/stretching surface. The model for hybridization of the mixture of alumina Al2O3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left( {{\ ext{Al}}_{{2}} {\ ext{O}}_{{3}} } \\right)$$\\end{document} and copper (Cu) nanoparticles in the sodium alginate (SA) base fluid under heat source/sink, nonlinear thermal radiation, and viscous dissipation. The fundamental partial differential equations (PDEs) are simplified using an appropriate similarity conversion to generate the ordinary differential equations (ODEs). The analytical computation occurs in the MATHEMATICA program implementing the homotopy analysis method (HAM). In terms of code validity, our results are preferable to previous findings. The features of several parameters against the velocity, surface friction coefficient, entropy, temperature, and Nusselt number are described through graphs. According to our findings, the rise in the Brinkman and Reynolds numbers enhanced the total entropy of the system. Furthermore, the nanoparticle volume fraction and viscus dissipation magnifies the fluid temperature while retards the flow profile throughout the domain. Fluid velocity declined due to the Lorentz force using magnetic impact applications. The imprecision of nanofluid and hybrid nanofluid volume fractions was modelled as a triangular fuzzy number (TFN) [0%, 1%, 2%] for comparison. The double parametric approach was applied to deal with the fuzziness of the associated fuzzy parameters. The nonlinear ODEs convert into fuzzy differential equations (FDEs) and use HAM for the fuzzy solution. From our observation, the hybrid nanofluid displays the maximum heat transfer compared to nanofluids. This important contribution will support industrial growth, particularly in the processing and manufacturing sectors. The percentage increase in skin friction factor is 18.3 and 15.0 when α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document} and β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document} take input in the ranges of 0 ≤ α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha$$\\end{document} ≤ 0.8 and 0 ≤ β\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\beta$$\\end{document} ≤ 1, respectively.

Research on the effect of the variation of laser power on the contour control and performance control of laser cladding Ni60CuMo/IN718 coating on RuT300

To improve the wear resistance of Vermicular cast iron (RuT300) surface and overcome the crack inhibition bottleneck of high-hardness coating, a Ni60CuMo/IN718 composite coating was fabricated on RuT300 surface. Results indicate the cracking-free coating with a maximum hardness of 475 HV0.5 at 800 W. In addition, the hard phases MC (M=Nb, Ti), Cr7C3, CrB and the self-lubricating phase Cu3.8Ni were in-situ synthesized in the coating. Increasing laser power raised C content from substrate in the molten pool, providing more C elements for in-situ synthesized Cr7C3. Along with the consumption of Cr by carbide generation, the Cr content used for in-situ synthesized CrB decreases. Moreover, the hardness of Cr7C3 is lower than that of CrB, and the low-hardness Fe in the substrate intensifies the coatings dilution with the increasing power. Therefore, these effects result in a non-positive correlation between the increase of laser power and the coatings hardness. Due to the better anti-wear effect of the high hardness coating, the hardest coatings have the lowest wear rates at room temperature (RT). Abrasive wear is the primary wear mechanism for these coatings at RT. Fe2O3 generated by high temperature friction plays a lubricating effect, but the coating with the low hardness softened by high temperature is not conducive to the compaction and forming of the oxide film. As a result, coatings that produce a moderate oxide film at 300 °C and 500 °C have a lower wear rate in the same environment. The main wear mechanism for the coatings is oxidative wear.

Tribological behaviors of nano-schistose MSH in phosphate/graphite composite lubricating coatings under different friction temperatures

Nano-schistose MSH was incorporated to enhance the tribological properties of phosphate/graphite composite coatings at various friction temperatures. The composite coatings demonstrated optimum friction-reducing and anti-wear performance at 200 ℃ due to synergistic friction between nano-schistose MSH and graphite. However, the friction-reducing performance of the composite coatings declined at 500 ℃ due to the structural cleavage of nano-schistose MSH. Nevertheless, a composite tribo-film with exceptional mechanical properties was in-situ formed on the worn surface through tribo-chemical and mechano-chemical reactions between nano-schistose MSH and the counterface. Consequently, further abrasion on the worn surface was effectively reduced during the friction process, resulting in a significantly prolonged service life of the composite coatings even at 500 ℃.

Дюрометричний аналіз зміцнення приповерхневого шару ADI при терті під впливом TRIP-ефекту

Features of strengthening of the near-surface layer of ADI during friction due to strain-induced martensitic transformation were analyzed by duromeric methods. Indentation under continuous loading (Meyer hardness, HM) and Vickers microhardness Hμ were used. Pop–ins are observed on the ADI continuous load curves, which indicate martensitic transformations during indentation. The effect usually exists at a load of ~0,1 H and an depth of ~1,5 μk. The average microhardness of the initial sample is Hμ ≈ 4,89 GPa. After wear, the average value increases to Hμ ≈ 6,92 GPa. Statistical analysis of the microhardness distribution of the sample after wear revealed that a third of the indentations have abnormally high hardness, which is characteristic of deformation-induced martensite. Probably, these indents are obtained from regions of the structure where deformation-induced martensitic transformation took place. Increasing the indentation load practically does not affect the determination of the microhardness of the initial sample, but reduces the hardness of the sample after wear. This indicates the gradient nature of deformation and phase-structural rearrangements in the near-surface layer during wear. As the friction temperature increases, there is a decrease in microhardness in the wear zone. This is explained by the departure from the temperature range of the martensitic transformation, due to which the TRIP effect is weakened. The maximum degradation of microhardness is observed between room temperature and 50 oC. Keywords: ADI materials, durometric studies, TRIP-effect, wear.

MHD nonlinear natural convection from a uniformly moving porous vertical plate with constant heat and mass flux in the presence of thermal radiation, diffusion‐thermo, heat sink, and chemical reaction

AbstractAn attempt has been made to investigate the problem of nonlinear free convection heat and mass transfer flow past an infinite vertical porous plate embedded in a porous medium by taking into account thermal radiation and heat sink with constant heat and mass flux. Transversely oriented and of uniform strength , a magnetic field has been introduced to the fluid area. The nonlinear density variation with temperature as well as concentration are the basis for the current physical situation, which is explained by this mathematical model. Exact solutions are derived for momentum equation, energy equation, and species continuity equation under the relevant boundary conditions. The dimensionless governing equations are analytically solved. The influence of various physical parameters, such as Dufour number, Schmidt number, thermal Grashof number, magnetic parameter, mass Grashof number, heat sink, thermal radiation, Prandtl number, chemical reaction parameter on the flow, and transport characteristic, has been presented graphically and in tabular form. The novelty of the present investigation is that here both constant heat and mass flux at the plate are taken into account in addition to thermal radiation and heat sink. The findings of the mathematical study demonstrate that velocity, temperature, and skin friction intensify with a rise in the Dufour number this is due to the fact that the convection current becomes stronger as the Dufour number rises. Fluid's concentration declines as the Schmidt number grows, or the concentration rises as the mass diffusivity rises. Fluid temperature is enhanced with high thermal diffusivity. Frictional resistance on the plate hikes due to thermal buoyancy force.

Vacuum tribological properties in Cr-doped H-DLC self-lubricating radial spherical plain bearings

To improve the vacuum tribological properties of the self-lubricating radial spherical plain bearings (SSPBs), the multi-layered Cr-doped hydrogenated diamond-like carbon films (Cr-H-DLC) and non-doped H-DLC films as the lubricating materials were prepared on the inner ring with an outer spherical surface and the outer ring with an inner spherical surface by unbalanced magnetron sputtering. The microstructure, phase composition, tribological properties, and failure mechanism of Cr-H-DLC SSPBs and H-DLC SSPBs were investigated. The results showed that the microstructure of the outer and inner spherical surfaces for the two kinds of SSPBs was dense. The microgram indicated that the self-lubricating film thickness of the outer spherical surface was greater than that of the inner spherical surface. What is more, the Raman spectra showed that the self-lubricating coating on the outer spherical surface contains more graphite characteristics of sp2 hybrid bonds based on the value of ID/IG. According to the vacuum tribological test, the oscillating life of H-DLC SSPBs was higher than that of Cr-H-DLC SSPBs. Moreover, the change law of friction torque and friction temperature rise showed that the testing process of coated SSPBs could be divided into running-in, stable, and failure periods. Compared with the ID/IG values before and after the vacuum test, it could be inferred that the graphitization of the sp3 hybrid bond in the self-lubricating film on both spherical occurred. Based on the microscopic wear morphology, the failure mechanism of H-DLC SSPBs and Cr-H-DLC SSPBs were abrasive wear and fatigue wear. When the lubricating layer of the friction interface was worn, the metal substrate of the inner and outer rings would contact, resulting in adhesive wear.

A lubrication model for bubbly oil lubrication with interfacial effect and thermal effect using the theory of multiphase mixtures

Bubbly oil lubrication is a type of lubrication method. However, the lubrication model of the bubbly oil has not been thoroughly considered. This paper aims to investigate the modelling for bubbly oil lubrication considering the interfacial effect and thermal effect, and a theoretical model is established based on the theory of multiphase mixtures. The interfacial and thermal effects on the static characteristics of a thrust bearing are analyzed. A test rig for the thrust bearing is developed to measure the static characteristics of the bearing under bubbly oil lubrication. The results show that the bearing static characteristics, i.e. bearing temperature rise, film thickness, friction torque, and volume flow, increase with consideration of three interfacial effects; the bearing temperature rise increases but the film thickness, friction torque, and volume flow rate decrease with consideration of the three thermal effects; the thermal effect on the bearing static characteristics is greater than the interfacial effect.

High wear resistance and strength of Hastelloy X reinforced with TiC fabricated by laser powder bed fusion additive manufacturing

Hastelloy X (HX) alloy as a typical solid solution strengthened nickel-based superalloy, has been widely used in the preparation of hot end components. The microstructure evolution and properties of HX alloy and nano-TiC reinforced HX alloy (TiC/HX) formed by laser powder bed fusion (LPBF) were studied. The results show that adding 3 wt% nano-TiC particles can not only inhibit the formation of cracks, but also effectively improve the dry sliding friction, wear properties and room temperature tensile properties. Nano-TiC particles can significantly promote the competitive growth of dendrites, refine the grains, and reduce the residual thermal stress. In addition, it can significantly improve the shear modulus and tensile strength. Under the same forming parameters, the wear rate of the nano-TiC/HX composite material is 51 % lower than that of the pure HX alloy, only 174.49 μm3/(N·mm). At the same time, the tensile strength of the alloy increased from 708 MPa to 1131 MPa, the yield strength increased from 619 MPa to 842 MPa, and the elongation doubled to 16 %.

Couple stress effects on the MHD triple-diffusive oscillatory flow in a fluid-saturated porous layer

The motivation of this paper is to explore an oscillatory flow of a magnetohydrodynamics (MHD) couple stress fluid with heat and mass transfer analyses through a porous medium. The modified Darcy–Brinkman couple stress fluid model is employed. There could be many potential applications of this study, such as thermal system, solidification of liquid crystals, cooling of metallic plates in a bath, exotic lubricants and colloidal solutions. In the wake of these potential applications, the study of MHD couple stress fluid flow with additional diffusing components has been found to be innovative and very interesting in the analysis of the influence of combined magnetic effects, couple stress fluid and two solutes. A governing coupled nonlinear partial differential equation with boundary constraints represents the modeled flow problem. In addition, these equations are converted into nondimensional form by employing the suitable nondimensionalizing quantities. It is possible to attain analytic solutions to the dimensionless equations that control the liquid flow, and the consequences of the flow’s confines on velocity, temperature, concentration and skin friction profile are examined and also the results are discussed through graphs. It is noteworthy that when the injection level on the heated plate is increased, the skin friction on each channel plate also increases.

Insights into the thermal characteristics and dynamics of stagnant blood conveying titanium oxide, alumina, and silver nanoparticles subject to Lorentz force and internal heating over a curved surface

Abstract It is very significant and practical to explore a triple hybrid nanofluid flow across the stuck zone of a stretching/shrinking curved surface with impacts from stuck and Lorentz force factors. The combination (Ag–TiO2–Al2O3/blood) hybrid nanofluid is studied herein as it moves across a stagnation zone of a stretching/shrinking surface that curves under the impact of pressure and Lorentz force. Exact unsolvable nonlinear partial differential equations can be transformed into ordinary differential equations that can be solved numerically by similarity transformation. It was discovered that predominant heat transfers and movement characteristics of quaternary hybrid nanofluids are dramatically affected. Numerous data were collected from this study to illustrate how parameters of flow affect the temperature, velocity, heat transmission, and skin friction characteristics. The axial and radial velocities for both fluids (Newtonian and ternary hybrid nanofluid) are increased due to the increasing function of the curvature parameter, magnetic field, and suction parameter. Additionally, the direct relationship between the temperature and heat transfer decreases the heat transfer rate by the curvature parameter, magnetic field, suction parameter, Prandtl number, and heat source/sink. The higher the values of the curvature parameter, the higher the shear stress and velocity.

Preparation of ionic liquid@SiO2 nanocapsules for improving self-lubricating performance of PA6 composites

A novel high temperature resistance ionic liquid@SiO2 (IL@SiO2) nanocapsules were successfully prepared in order to meet the high temperature processing requirement. The average diameter and the loading capacity of as-obtained IL@SiO2 nanocapsules were about 420 nm and 44.7 wt% respectively. The IL@SiO2 nanocapsules showed excellent thermal stability with a 340 °C initial thermal degradation temperature. The frictional and wear properties of PA6 composites containing IL@SiO2 nanocapsules under different friction temperature were studied systemically. Self-lubricating PA6 composites with 3 wt% IL@SiO2 nanocapsules showed the optical tribological propertied. The corresponding friction coefficient of PA6 composites reduced by 38.9%, and the wear rate also showed a 60.7% decrease compared with pure PA6. Unlike most microcapsules, the addition of nanocapsuels did not cause an undesirable and obvious decrease in mechanical properties of PA6. Anti-wear and friction-reduction mechanism were depth analyzed, and results revealed that IL core and SiO2 wall in nanocapsules synergistically contribute to improve self-lubricating performance of PA6 composites.

Non-linear thermal radiation and entropy generation on MHD Casson and Williamson hybrid nanofluids across a curved stretching sheet with Cattaneo-Christov heat flux model

This entire study aims to prove the impacts of non-linear thermal radiation and entropy generation on Casson and Williamson hybrid nanofluids through a comparative analysis of the magnetohydrodynamic flow in a porous, curved stretching sheet with the Cattaneo-Christov heat flux model. We used hybrid nanofluid blood based on gold (Au) and Aluminium oxide (Al2O3) nanoparticles. The governing non-linear coupled Partial Differential Equation (PDE) are transformed into non-linear coupled Ordinary Differential Equations (ODE) using the Maple software solver using the Homotopy Perturbation Method. The Homotopy Perturbation Method (HPM) results are compared with the Numerical Method (NM) results, and HPM gives reliable results. The results are provided through the table and graphical representations for several parameters such as velocity, temperature, entropy production, Bejan number, Nusselt number, and skin friction respectively. The velocity profile decreases for Williamson and Casson hybrid nanofluids over a curved stretching sheet while the magnetic field parameters increase. Due to magnetic force associated with Lorentz force, which is known as resistive force, velocity decreases. The Magnetic field on the entropy generation for Casson and Williamson hybrid nanofluids. As the Magnetic field increases, the entropy generation increases for Williamson and Casson hybrid nanofluids. This problem is used in various biomedical situations, including resistive impedance to flow, arteria wall shear stress, and heating impact owing to radiation throughout the surgical process by altering the strength of the applied magnetic field.

Simulation of electrical contact wear on the rough surfaces of ultra-high-voltage transmission line fittings

A novel electrical contact wear simulation method was proposed to characterize the electrical contact wear of fittings in ultra-high-voltage transmission lines by combining line fittings with the Archard wear model and oxidation loss theory. In this method, a three-dimensional (3D) rough body was generated by using the Weierstrass–Mandelbrot fractal function to simulate the contact surface. An electrical contact wear subroutine was developed, and the wear state was updated using arbitrary Lagrangian–Eulerian adaptive grid technology. Finally, finite element software was used to perform thermal stress wear coupled analysis. The results show that the wear volume, wear depth and friction temperature obtained by the rough electric contact model were 2.71 times, 4.21 times and 2.18 times of the common ideal plane model, respectively. In the rough model, the wear depth of the nodes initially accelerated, subsequently slowed down, and again accelerated with time. The friction high temperature region was distributed in a point pattern, and the temperature difference between the contact region and the non-contact region became obvious.

The Tribological Behavior of Cast Iron by Laser Surface Texturing under Oil-Lubricated Initial Line Contact for Rotary Compressor

The tribological behaviors of cast iron by laser surface texturing were experimentally compared with the behavior of untextured by unidirectional rotary sliding friction and wear tests under oil-lubricated initial line contact. The friction coefficient and temperature rise were analyzed with the increasing load applied by block-on-ring tests. In addition, the wear loss and wear mechanism were also investigated through the surface topographies analysis. The results showed that the tribological improvement strongly depended on the contact form. For the oil-lubricated initial line contact in this work, the textured surface showed a better frictional advantage with a lower friction coefficient and lower temperature rise. The hydrodynamic effect enhanced the load-carrying capacity of the oil film and increased the film thickness. The friction coefficients were 11~64% lower than those on the untextured one. Meanwhile, the textured surface deteriorated the wear behavior due to the coupling effect between the micro-cutting effect of the texture edges and the material deformations of the counter surface. The material loss induced by abrasive wear and fatigue wear was the dominant wear mechanism. Namely, the laser surface texturing improved the friction properties but reduced the wear resistance.

Research on wear rate of train brake pads driven by small sample data

Increased wear leads to the failure of brake pads. Both the International Union of Railways (UIC) and the China Railway Production Certification (CRCC) take wear rate as an extremely important parameter that characterizes the degree of wear, and its value can provide reference for the braking performance of the brake pads. Since the braking performance test of brake pads is time-consuming and costly, the sample data of wear rate is small. In this study, we explore the coupling relationship between the wear rate of train brake pads and its features such as initial braking speed (IBS), braking pressure (FB), braking temperature and average coefficient of friction (ACOF), and propose a Butterfly Optimization Algorithm-Back Propagation (BOA-BP) method suitable for small sample data for the wear rate prediction of brake pads. The grey relational analysis (GRA) and Pearson correlation analysis (PCA) are used to arrive at preferred features for the prediction of wear rate of brake pads, such as IBS, FB, braking distance and ACOF. The dynamic GM(1, N) and the least square method are used for sample expansion. Furthermore, the wear rate is designated as the output feature parameter and the preferred features are designated as the input feature parameters, a BOA-BP model is established for predicting the wear rate of brake pads. The results show that the wear rate obtained by dynamic GM(1, N) is consistent with the actual braking test, the maximum temperature and the braking pressure are important factors affecting wear rate. Compared to the comparison methods such as PSO-BP, GA-BP, and BP, the BOA-BP exhibits better advantages in prediction with small samples, and the average prediction accuracy with 33 sets of data and 99 sets of data are 95.70 % and 97.21 % respectively.

Experimental study on mechanical properties of Beishan granite in the mild temperature range

The response of mechanical property to temperature, especially in the mild temperature range, is important for the high-level waste (HLW) geological disposal engineering. To study the temperature effect on the deformation properties and the mobilization of strength of Beishan granite, the incremental cyclic loading-unloading compressive tests under various temperatures (T) and confining pressure (σ3) conditions (T = 25 °C, 60 °C and 90 °C, σ3 = 0 MPa, 5 MPa and 20 MPa) were carried out on Beishan granite. Results showed: (1) During the entire compression process, the cohesive strength is weakening while the frictional strength is strengthening. The CWFS model was developed considering the temperature effect. (2) For the peak strength, the cohesion decreased while the friction increased with increasing temperature in the range of 25 °C–90 °C. (3) The mechanism of cohesion weakening and friction strengthening with increasing temperature was discussed based on the micro-structure measurement. Clear thermal induced crack/pore closure was observed in granite after mild temperature treated, which contributes to friction strengthening and stiffness improvement. (4) The strength response to temperature (cohesion weakening and friction strengthening with increasing temperature) will result in ‘transition pressure (10.1 MPa for crack damage stress, and 14.9 MPa for peak strength)’ for Beishan granite under mild temperature that the surrounding granite would be strengthened by the elevated temperature under higher confining pressure. The transition pressure is important for high-level waste geological disposal engineering in repository layout design optimization.

Novel Approach to Address Brownish Edge Band in Low Alloy Cold Rolled Steel Used in Tin Plate

Thin film formation of lubricant plays a key role in supporting lubrication and abating wear. During cold rolling of steel, esters, or film formers in rolling oil play an important role in the mixed lubrication regime. The property of the lubricant holds the key to achieving the mean film thickness during the mixed lubrication regimen. Band formation in cold rolling is often related to inadequate acid pickling. During cold rolling operation, the film formation between asperities plays an important role in controlling friction and coil temperatures. A well formulated lubricant ensures smooth transition of lubrication throughout the range of roll bite temperature and also across the lubrication regimes. A sudden spike in coefficient of friction (CoF) can often lead to increased wear and abnormal increase in coil temperatures resulting in band formation. The study highlights degradation of oil sample leading to the problem and the role of key lubricant properties in esters in mitigating the problem.

Computational Studies of the Aerophysical Characteristics on the Head Part of the Supersonic Body of Rotation During Flight Along Trajectories

The use of modern computer systems for calculating the aerophysical characteristics of supersonic bodies of revolution together with the calculation of the flight trajectory under conditions of continuously changing Mach and Reynolds numbers of the oncoming flow, the presence of transient regimes and non-isothermality in near-wall flows is often not possible due to the complexity of the organisation of the computational process. By using a number of integral methods for calculating inviscid flows and viscous compressible near-wall flows, taking into account the non isothermality and intermittency of the boundary layer, a method has been developed for calculating the friction and heating of supersonic bodies of revolution on the flight trajectory. On the basis of well-known flight experiments, the correlation dependences of the Reynolds numbers of the beginning of the transition on sharp cones were obtained and the method of corrections for spherical blunting of the head part was implemented. By calculating the intermittency function, the changeability of flow regimes in the boundary layer is established for a number of trajectories of the supersonic uncontrolled rocket projectile. Calculated dependences for aerodynamic friction, heat fluxes and projectile wall temperature on the flight time are obtained. The concept of combined calculation of aerophysical characteristics on the flight trajectory using numerical and integral methods is proposed.

A friction temperature model for dynamic bearing operation based on neural network and genetic algorithm

This study used intelligent algorithms and experimental data to investigate the dynamic temperature of bearings. A test rig was created for angular contact ball bearings to measure the temperature of two bearings precisely while independently controlling rotational speed, axial load, radial load, and grease content. The study analyzed the steady temperature of bearings under different operating conditions using a friction temperature model based on SKF bearings. The bearings temperature was computed using traditional backpropagation neural network (BPNN) and genetic algorithms (GA). The study compared the results obtained through the SKF model and the actual temperature against those produced methods. GA displayed a higher level of accuracy and robustness. Upon evaluation, it was determined that both intelligent methods are suitable for processing variable data input. This article presents an intelligent approach to computing bearing temperature using statistical data analysis, which does not require analyzing dynamics, thermodynamics, or lubrication principles. The method's ability to compute transient temperature without boundary conditions or constraints makes it highly versatile. This feature renders it a valuable tool for bearing design and temperature control.