Various Angles Of Inclination Research Articles

Исследование потерь напора при движении кипящего двухфазного потока в наклонных трубах испарителя судовой холодильной машины

The study of pressure losses at boiling two-phase flow movement in vertical and inclined pipes of evaporators of ship refrigeration units is carried out. The study of the ascending two-phase flow is promising from the point of view of practical application. Such a movement is typical for various types of industrial heat exchange equipment, including for the development of promising types of evaporators, for example, vertical apparatuses for ships in which internal boiling of the refrigerant occurs. A methodology has been developed and an experiment has been set up to study the processes in the steam generating channels of refrigeration units at various angles of inclination with a fixed height. At the same time, the length of the channel changed, it became possible to analyze friction losses. A new approach has been applied that brings the model as close as possible to the actual boiling process, taking into account the constant increase of steam in the channel. Experimental studies have been carried out and data on pressure losses have been revealed when the angle of inclination of the steam generating channel changes. The main dependences and various components of hydraulic resistances during the movement of a boiling two-phase flow are presented. Based on the data obtained, the justification of ship evaporators transition of refrigeration units to the vertical arrangement of the heat exchange steam generating beam is proved. The results obtained indicate that an increase in the slope of the pipe, provided that the height is maintained, leads to an increase in pressure losses. Applicability to marine refrigerating machines has been determined – the transition to vertical apparatuses has advantages, primarily in reducing pressure losses. The obtained set of data allows to recommend the design of vertical evaporators for auxiliary ship installations.

Research on robotic belt grinding method of blisk for obtaining high surface integrity features with variable inclination angle force control

The blisk was a new type of component for high-performance aero-engines, which could significantly improve the energy efficiency ratio of the engine, however there were also shortcomings such as narrow structure and difficult material removal. Robotic belt grinding was widely used in the processing of key complex surfaces such as blades, fairings and propellers, which is due to its large processing space and high flexibility. Nevertheless, how to improve the surface integrity of the blisk under the premise of ensuring the profile accuracy was a challenging problem. In view of the above problems, this study started with the grinding force, and innovatively proposed a robotic belt grinding method for high surface integrity of blisk based on variable inclination angle force control. Firstly, a belt grinding robot based on macro-micro-end hand structure and electromagnetic force-controlled end was designed based on indirect arm-winding control. Secondly, an adaptive variable impedance compliance based blisk grinding model was established through the relation expression of grinding end and the mathematical formula of inclination contact micro-surface control, which effectively coordinates the coupling relationship between force control and trajectory under inclined attitude. Lastly, the experimental study proved that the normal grinding force of this method was stable and the error was 1.14 %, the surface hardness and residual compressive stress were improved by about 8.57 % and 52.82 % respectively, the surface morphology was uniform and the surface defects are well suppressed. The surface integrity of the blisk was significantly improved.

Heat and Mass Transfer On MHD Flow Problems with Hall and Ion Slip Effects On Exponentially Accelerated Plate

We in this paper intended to investigate heat and mass transfer for MHD free convective flow for exponentially accelerated plate. The effects of Ion slip and Hall are studied considering variable temperatures, concentration, and angle of inclination. We applied finite element analysis for solving governing equations. Flow velocity, concentration and temperature’s graphical profiles are examined for non-dimensional parameters. Flow reversal is prevented due to magnetic field, is observed. Velocity experiences retarding effect due to angle of inclination, this helps in acknowledging drag force in seepage flow.

Indentation and Detachment in Adhesive Contacts between Soft Elastomer and Rigid Indenter at Simultaneous Motion in Normal and Tangential Direction: Experiments and Simulations.

In reported experiments, a steel indenter was pressed into a soft elastomer layer under varying inclination angles and subsequently was detached under various inclination angles too. The processes of indentation and detachment were recorded with a video camera, and the time dependences of the normal and tangential components of the contact force and the contact area, as well as the average contact pressure and average tangential stresses, were measured as functions of the inclination angle. Based on experimental results, a simple theoretical model of the indentation process is proposed, in which tangential and normal contacts are considered independently. Both experimental and theoretical results show that at small indentation angles (when the direction of motion is close to tangential), a mode with elastomer slippage relative to the indenter is observed, which leads to complex dynamic processes-the rearrangement of the contact boundary and the propagation of elastic waves (similar to Schallamach waves). If the angle is close to the normal angle, there is no slipping in the contact plane during the entire indentation (detachment) phase.

Signatures of a spinning supermassive black hole binary on the mas-scale jet of the quasar S5 1928+738 based on 25 yr of VLBI data

ABSTRACT In a previous work, we have identified the spin of the dominant black hole of a binary from its jet properties. Analysing Very Long Baseline Array (VLBA) observations of the quasar S5 1928+738, taken at 15-GHz during 43 epochs between 1995.96 and 2013.06, we showed that the inclination angle variation of the inner (<2 mas) jet symmetry axis naturally decomposes into a periodic and a monotonic contribution. The former emerges due to the Keplerian orbital evolution, while the latter is interpreted as the signature of the spin-orbit precession of the jet emitting black hole. In this paper, we revisit the analysis of the quasar S5 1928+738 by including new 15-GHz VLBA observations extending over 29 additional epochs, between 2013.34 and 2020.89. The extended data set confirms our previous findings which are further supported by the flux density variation of the jet. By applying an enhanced jet precession model that can handle arbitrary spin orientations κ with respect to the orbital angular momentum of a binary supermassive black hole system, we estimate the binary mass ratio as ν = 0.21 ± 0.04 for κ = 0 (i.e. when the spin direction is perpendicular to the orbital plane) and as ν = 0.32 ± 0.07 for κ = π/2 (i.e. when the spin lies in the orbital plane). We estimate more precisely the spin precession velocity, halving its uncertainty from $(-0.05\pm 0.02)$ to $(-0.04\pm 0.01)^{\circ }\, \mathrm{yr}^{-1}$.

V자형 튜브 배열의 경사각 변화에 따른 풀비등 열전달

V자형 튜브 배열의 경사각 변화에 따른 풀비등 열전달

Cracking Behavior and Stress Field Evolution in Coal Specimens Containing Bedding under Uniaxial Compression.

During the underground mining process, various coal seams with different bedding structures are often encountered. The presence of bedding structures is one of the primary factors that influence the strength and deformation characteristics of the coal seam and then affect gas extraction and gas disaster prevention. However, there is still a lack of mechanical properties of coal rock with structural anisotropy influenced by bedding structures. In this study, numerical models were established by using the particle flow code method to simulate coal specimens containing bedding with varying inclination angles. The results demonstrate the impact of the bedding inclination angle on the mechanical properties, crack propagation patterns, and the temporal and spatial evolution of the stress field in coal specimens with bedding during the loading process. Furthermore, three crack initiation patterns were investigated for coal specimens with different bedding angles. Additionally, the quantitative relationship between the mechanical properties and the fractal dimension was analyzed. The numerical simulation results were effectively validated through laboratory tests.

Mixing tank hydrodynamics and mixing efficiency for propeller impellers

In this study, the distribution of axial and radial velocities with the use of a PIV laser system was determined and the mixing power in a mixing tank with narrow and wide propeller impellers was measured. The pumping capacity and secondary circulation values in the mixing tank were calculated and on this basis, the energy efficiency of the operation of both types of propeller impellers was determined and compared with the efficiency of turbine impellers with inclined blades. It turned out that propeller impellers with wide blades are most effective as regards the amount of energy that should be supplied to the mixing tank to achieve the required mixing time. It was found that the share of pumping capacity in the total secondary circulation is almost twice as high as the share of induced circulation. Correlation equations for the dependence of the mixing power and dimensionless flow numbers on the pitch of the propeller blade were also formulated. All the results obtained were compared with the works of other authors. The paper also found that propeller impellers with a variable angle of inclination of the blade α depending on the current radius do not meet the theoretical assumption of a constant axial velocity of the liquid flowing out from of the impeller zone. For small radii of the impeller the explanation for this observation is the presence of the hub and shaft in the axis of the mixer and the effect of liquid slip for the steep agitator blades near the hub. For radii close to the radius of the stirrer, the reason is generation of induced circulation as the expense of the kinetic energy of the liquid flowing out of the impeller area.

Influence of build angles on thin-wall geometry and surface texture in laser powder directed energy deposition

Metal additive manufacturing (AM) is being used for mission-critical applications in both developmental and production components, driven by economic and technical benefits. Laser powder directed energy deposition (LP-DED) allows manufacturing of thin wall geometric features for various components at diameters larger than 2 m. The characterization of geometric capabilities and limitations is critical for establishing guidelines for end users of the technology. Within this study, several samples of enclosed vertical tracks were fabricated and characterized using LP-DED, with 1 mm-thick walls and varying inclination angles up to 45° using the NASA HR-1 alloy (Fe-Ni-Cr). The wall thickness, melt pool, and surface texture, inclusive of waviness and roughness, were evaluated and results presented. The experimental results indicate that the wall thickness increases exponentially above 30°. The surface texture was shown to be dependent on 1) excess powder adherence, 2) melt pool irregularities causing material droop, and 3) excess material. The experiment revealed that the mean roughness reduces with increasing wall angle for the downskin surface. The upskin roughness reaches a maximum peak at 20° and slowly reduces as powder adheres within the valleys. Both the downskin and upskin surface textures are dominated by irregular waviness generated by the melt pool.

The whirl direction and characteristics of rotor system under maneuvering flight

Maneuvering flight can generate the asymmetry of the stiffness or damping to an engine rotor system, as so to influent the whirl direction and characteristics of rotor system. In this article, the identification method for orbit direction is provided for a rotor system under maneuvering flight condition. By a simulation example, the variable movement shapes about rotor under maneuvering flight are illustrated through cases as the mixed and the pending whirls. The results show that the original low-order critical speed in the backward or forward whirl mode changes to the mixed whirl while considering the impact of maneuvering flight, where some backward and forward critical speeds in the same order are almost overlapped as one critical speed which in the mixed whirl mode. Maneuvering flight results in dynamic eccentricity of the rotor shaft, and the orbits of nodes in the mixed whirl are a series of ellipses with variable inclination angles. The case with pending whirl direction is finally determined as a mixed whirl by the orbit direction graph. The whirl directions of orbits on bearings or the contact angle of bearings maybe different under maneuvering flight can be explained from the rotor dynamical view.

Flutter Characteristics of a Joined-Wing Unmanned Aerial Vehicle with Variable Dihedral Angles

A parametrized aeroelastic model is built to study the flutter characteristics of a new joined-wing unmanned aerial vehicle (UAV) with variable dihedral angles. First, the substructure modal synthesis is introduced to construct the structural finite element model of the joined-wing UAV according to the connection relations between adjacent wing segments. Second, the doublet-lattice method is introduced to obtain the aerodynamic characteristics of each airfoil in subsonic flow, taking into account the interactions between each airfoil. After that, a parametrized aeroelastic model with variable inclination angles is established, and the p-k method is used for flutter calculations. The results show that the joined-wing UAV has wide ranges of flutter velocities and flutter frequencies, which show a nonlinear growth trend with the increase of the tail inclination angle owing to the flutter mode transitions. In addition, the forward sweep angles of the joined wing and the rigidity of the tail links both have significant impacts on the flutter characteristics of the joined-wing UAV.

Performance enhancement of a conical solar still by optimizing inclination angle

Conical solar stills have the benefit over simple solar stills in that all of the top portions are exposed to the same solar radiation at all times and in all locations, eliminating the need to specify the direction of the sun's rays. Additionally, unlike the walls of the basic distillation system, the walls of the conical distiller do not induce shadowing inside the basin. The goal of the present investigation is to develop and build new distillers with a transparent conical cover inclined from the horizon at various degrees in order to attain the best cumulative yield of Conical Solar Stills (CoSS). An experimental test is conducted on three conical solar stills with varied inclination angles (30, 45, and 60° with the horizon) in order to determine the ideal angle of CoSS that provides the maximum performance. According to experimental findings, employing a conical solar still at a 30° inclination angle results in a maximum cumulative production of 5.90 L/m2, which is an improvement of 16.83 and 55.26% over CoSS at 45 and 60°, respectively. When utilising the CoSS, however, yields of 5.05 and 3.80 L/m2 are obtained at inclination angles of 45 and 60°, respectively. In order to get the maximum performance conical solar stills, CoSS with a 30° inclination angle is advised based on cumulative yield data and daily efficiency.

Analysis Thermal Behavior of a Locally Heated Solar Chimney

This paper presents the thermal behavior of a partially heated solar chimney under hot-humid climate conditions. The solar chimney (SCH) is 2 m high and 0.8 m wide and consists of an absorber plate and a translucent plate. The SCH allows a cavity thickness variation from 0 to 0.28 m, an inclination angle variation from 0 to 90º, and allows varying the amount of energy absorbed by the absorber plate and translucent plate. These plates were heated by resistors, simulating a solar irradiance range of 225 to 900 W/m2 (absorber plate) and from 12.15 to 50 W/m2 (translucent plate). Twelve tests were conducted with different configurations varying the power supplied to both plates, the thickness of the absorber plate cavity, and the 90º inclination angle. The variables measured were temperature, air velocity at the inlet, and heat flow on the side walls and rear wall. As a result, a maximum air renewal of 51.43 ACH was obtained, equivalent to the air changes used in a paint booth. The results show that the partially heated solar chimney can be used as a passive ventilation system for air renewal.

Research on mass distribution characteristics of the behind armor debris of the EFP penetrating target

Based on the AUTODYN, a numerical simulation model for EFP warhead penetrating finite thickness target was established, and the mass distribution characteristic of the armor debris behind target was analyzed. The result shows that the whole mass of behind armor debris(BAD) of the EFP with 1790m/s and target with 0° inclination angle increased and the quantity of BAD firstly increased and then decreased as target thickness ranging from 10mm to 70mm. For the experiments with employing the EFP with 1790m/s and 40mm target thickness, the BAD mass initially rose and then to drop off, as well as the quantity of BAD increased over inclination angle increasing from 0° to 60°.According to the results with 0° inclination angle and 40mm target thickness, the quantity of BAD also increased and the mass generally decreased as EFP velocity increasing from 1.2km/s to 2.6km/s. Verifications were conducted by using EFP penetrating into the 40mm thickness target with varying inclination angles. The simulation results correlate with the experimental results reasonably well.

Experimental Study For a Laminar Natural Convection Heat Transfer From an Isothermal Heated Square Plate With and Without Circular Hole

An experimental investigation of natural convection heat transfer from an isothermal horizontal,vertical and inclined heated square flat plates with and without circular hole, were carried out in two cases, perforated plates without an impermeable adiabatic hole "open core" and perforated plates with an impermeable adiabatic hole "closed core" by adiabatic plug. The experiments covered the laminar region with a range of Rayleih number of (1.11x106 ≤RaLo≤4.39x106 ), at Prandtle number (Pr=0.7). Practical experiments have been done with variable inclination angles from horizon (Ф=0o ,45o,90o,135oand 180o),facing upward (0o≤Ф<90o), and downward (90o≤Ф<180o). The results showed that the temperature gradient increases while the thermal boundary layer thickness decreases when Grashof number and perforation ratio (m) increase . The temperature gradient for inclined position facing upward is less than facing downward,while the thermal boundary layer thickness is greater. The temperature gradient decreases while the thermal boundary layer thickness increases for perforated plates with an adiabatic core as compared with perforated plates without an adiabatic core. The value of average Nusselt number increases with increasing perforation ratio, and Grashof number for all specimens with and without an adiabatic core, also increases by increase in inclination of plates approaching the higher value at vertical position (Ф=90o), then decreases with increasing inclination of plates till horizontal position (Ф=180o). The average Nusselt number values for perforated plates with an adiabatic core are lower than for perforated plates without an adiabatic core for all perforation ratios. Maximum heat transfer rate occurs at perforated plate with perforation ratio of (m=0.1) without adiabatic core for vertical position (Ф=90o), at a range of Grashof number (1.576x106≤GrLo≤6.292x106 ), while the rate of heat transfer decreases with increasing perforation ratio for plates with and without adiabatic core for decrease in heat transfer rate area. The rate of heat transfer forperforated plates with circular hole is more than for perforated plates with square hole at the same perforation ratios (m=0.1,0.16,0.24 and 0.36). It found that the lack of core flow decreases the overall heat transfer rate by (6.477%) . There was a good agreement for the experimental present work results compared with other pervious results .

Экспериментальное исследование динамики процесса механообработки концевыми сфероцилиндрическими фрезами

Introduction. Due to a significant number of factors affecting the change in the properties of a dynamic system, excessively conservative processing conditions are chosen to ensure the high quality of the resulting product. This limits the efficiency of the process and leads to an increase in the cost of production. Accordingly, modern approaches are needed that will allow diagnosing the current state of processing and making timely decisions to replace the tool, correct or change the control program. The significance of the ongoing research is to propose a real-time monitoring approach to milling control to identify emerging processing errors, predict potential problems and improve uptime. Subject. The paper discusses the features of the real-time monitoring system during mechanical processing with a single- and double-edge cutting tool, taking into account acoustic wave filtering, minimizing surface roughness. The purpose of the work is to determine the effect of the inclination orientation of the ball-end tool on the surface roughness value using real-time monitoring during milling on CNC process equipment. Methods. The study provides methods of correlation and regression analysis. The calculated data were obtained by means of vibroacoustic diagnostics and measured in the range of values of the variable angle of inclination of the surface for single- and double-edge cutting tool based on the provisions of the theory of oscillations and vibroacoustic diagnostics, cutting theory, digital processing and digital filtering of signals. Results and discussions. Experimental data obtained during machining made it possible to determine that an increase in the angle of inclination of a single-edge cutting tool has practically no effect on the change in the amplitude parameters of roughness. The values of vibroacoustic diagnostics and roughness, when using a double-edge ball-end tool, show a consistent picture with the effects created by the angles of inclination and advance. The obtained solutions to the problems of monitoring and analyzing the roughness parameters can significantly reduce the amount of experimental research and clarify the idea of the practical implementation of the method of acoustic monitoring of the cutting process.

Free Vibration of Inclined Twisted Cables

This paper is aimed at simulating and investigating the coupled translational and rotational vibrations occurring simultaneously in inclined sagged cables. The three-dimensional behavior of the single-layered six wires strand stiffness results are reduced to effective one-dimensional behavior from the elasticity-based finite element behavior analyses under axial tension and torsional loads. These are directly compared with multiple one-dimensional analytical model results. The effective stiffness coefficients agreed well for the actual lay angle of the cable and at angles below 20 degrees with finite element models where internal contact was not considered. To find the cable natural frequency and corresponding modal shapes the derived primary stiffness and mass matrices are discretized over the inclined sagged cable using a finite element model where the two-node cable element has three translational and three rotational degrees of freedom. The vibration behavior is also studied using extensive experimental tests using the same cable geometry and material used in the numerical calculations. In addition to the physical experiments, the finite element model accuracy was also compared with results from a well-known analytical model available from the literature for horizontal cables, and the influence of the inclination angle variation was also investigated and compared with the computer finite element software ABAQUS for the same purpose. The results found confirm the correctness of the derived formulation, mathematical, and psychical importance of the six-degrees of freedom finite element model developed and the efficiency in evaluating the coupled cable dynamic behavior. It addition, the results highlight the fundamental dynamics of inclined cables and the role of the inclination angle, sag, and weight of the cable.

Analysis of contact pressure in a 3D model of dual-mobility hip joint prosthesis under a gait cycle

Hip joint prostheses are used to replace hip joint function in the human body. The latest dual-mobility hip joint prosthesis has an additional component of an outer liner that acts as a cover for the liner component. Research on the contact pressure generated on the latest model of a dual-mobility hip joint prosthesis under a gait cycle has never been done before. The model is made of ultrahigh molecular weight polyethylene (UHMWPE) on the inner liner and 316L stainless steel (SS 316L) on the outer liner and acetabular cup. Simulation modeling using the finite element method is considered static loading with an implicit solver for studying the geometric parameter design of dual-mobility hip joint prostheses. In this study, simulation modeling was carried out by applying varying inclination angles of 30°, 40°, 45°, 50°, 60°, and 70° to the acetabular cup component. Three-dimensional loads were placed on femoral head reference points with variations of femoral head diameter used at 22 mm, 28 mm, and 32 mm. The results in the inner surface of the inner liner, the outer surface of the outer liner, and the inner surface of the acetabular cup showed that the variations in inclination angle do not have a major effect on the maximum contact pressure value on the liner component, where the acetabular cup with an inclination angle of 45° can reduce contact pressure more than the other studied inclination angle variations. In addition, it was found that the 22 mm diameter of the femoral head increases the contact pressure. The use of a larger diameter femoral head with an acetabular cup configuration at a 45° inclination can minimize the risk of implant failure due to wear.

SHAPING OPERATIONS OF EXTRUSION AND ROTATION OF SOLID-STATE MODELING OF GEOMETRIC OBJECTS IN THE POINT CALCULUS

The shaping operations of extrusion and rotation within the framework of point calculus are implemented. The principles of parametrization of bodies in point calculus are described. When considering the extrusion operation, the cases of performing this operation at a right angle and with a variable inclination angle of the generatrix are taken into account. When implementing the rotation operation, the method of polar parameterization of the sketch plane is considered. Due to the use of point calculus, the proposed approach makes it possible to obtain body models in the form of a three-parameter set of points in the three dimensional space, the density of which depends on the parameters of the three dimensional model set by the designer. The analysis of existing systems of solid modeling and their capabilities in the direction of creating solid models of bodies is carried out. It showed that almost all of them provide the user with models presented as surfaces of body shells and are not filled with points. None of the existing CAD makes it possible to model a body in the form of a three parameter set of points. And when trying to use the proposed modeling apparatus within existing computeraided design systems (for example, outputting a model in the form of a set of points through the API of these systems), we risk getting a body model that is simply impossible to work with due to the excessive consumption of PC resources used for modeling (for example, even a model of a simple body with a high density of points can lead to a “freeze” of the system even on a computer with high computing power). In addition, the evaluation of the effectiveness of the mathematical apparatus embedded in the modeling systems cannot be effectively carried out since the mathematical basis of these CAD systems is a trade secret. In this case comparison is necessary, since the proposed three dimensional models consist of the same type of equations along all coordinate axes, which, if used correctly in CAD, can lead to significant savings in computing power due to parallelization of the data processing across different computational threads.

Functioning Features of Liquid Crystalline Cells Doped with CoFe2O4 Nanoparticles

The first experimental results on the functioning of liquid crystal cells doped with CoFe2O4 nanoparticles are presented. Transmission spectra in the visible and near-infrared range, dynamic parameters of the Fredericks effect, refractive characteristics, as well as wetting angles of the mesophase sensitized surfaces have been obtained. The measured surfaces were the K8 Crown glass, the conductive ITO and the ITO treated with a surface electromagnetic wave. The experiment was performed in order to establish the prospect of using such reliefs as a novel liquid crystal composite orientator sensitized with CoFe2O4 nanoparticles. A color change of the liquid crystal matrix, its refractive coefficients alterations, and the variation of inclination angle of the sensitized liquid crystal droplets on the considered reliefs were established. The time reaction parameters and the medium relaxation parameters were measured. It was proposed that the liquid crystal composition is a kind of an immersion medium that preserves properties of the introduced nanoparticles, which expands their application scope in optoelectronics and biomedicine.