Spiral Angle Research Articles

Research on structure characteristics of the helium-lubricated spiral grooved thrust bearing for helium turbine expander

The helium-lubricated spiral grooved thrust bearing of helium turbo expander was studied by numerically simulating the steady-state non-linear Reynolds equation, the Reynolds equation of the pressure was solved by finite difference method (FDM), the film pressure distribution is calculated iteratively by MATLAB program, the structural parameters including the spiral angle, the groove length ratio, the groove width ratio influenced on the static characteristics were analyzed. The results show that: The bearing loading capacity of helium lubricated spiral grooved thrust gas bearing is lower than that of air lubricated bearing under the same conditions; The viscosity of the lubricant only affects the gas carrying capacity of the thrust disc when the spiral groove is on the bearing, while the density of the lubricant has a greater influence on the bearing loading capacity; When the spiral groove is designed on the rotor thrust disc, the bearing loading capacity of the spiral grooved thrust bearing increases by 6% on average compared with that of the spiral groove on the bearing.

Computerized determination of the qualified region of main design parameters of face-milled hypoid gears with low shaft angle

The influence of main design parameters of hypoid gears with low shaft angle, namely, the offset, shaft angle, cutter radius, gear ratio, and the spiral angle of wheel, on the geometrical morphology the gear tooth surfaces has been investigated. Checks for obtaining appropriate top-land widths and spiral angles at the toe and heel sides have been developed and applied. The limits for the main design parameters that yield non-adequate tooth surfaces because- of top-land pointing, undercutting, or having a negative value of the spiral angle of wheel at the toe side have been investigated based on the results obtained by the simulation of a large number of cases of design. A specific computerized flow chart has been designed to iterate among the main design parameters to obtain a qualified region for them. With those results, a limiting graph has been proposed to get the list of recommended values of main design parameters and provide a reference for their selection. Finally, the results of loaded tooth contact analysis of two cases of design arbitrarily chosen from the proposed limiting graph of recommended values are shown to verify its applicability to yield to successful designs with favorable conditions of meshing and contact.

Fluid Inertia Effect on Spiral-Grooved Mechanical Face Seals Considering Cavitation Effects

An extended Reynolds equation is presented to evaluate the effects of the fluid inertia and cavitation on the performance of spiral-grooved mechanical face seals under high-speed conditions. Segregated finite element procedures are employed to solve the fluid inertia terms and the fluid film pressure distribution with the artificial viscosity stabilization strategy and streamline-upwind/Petrov-Galerkin (SUPG) finite element method. The pressure jump is captured at the sudden variation in film thickness. The fluid inertia effect on the sealing performance is determined at different rotational speeds, groove depths, and spiral angles. The results show that the inertia effect due to the film thickness discontinuities improves the load-carrying capacity and increases the leakage rate. The convective inertia forces in the sealing gap flow promote fluid cavitation. The fluid inertia effect on the sealing performance is closely dependent on the spiral angles.

Improved 3D real-time MRI of speech production.

To provide 3D real-time MRI of speech production with improved spatio-temporal sharpness using randomized, variable-density, stack-of-spiral sampling combined with a 3D spatio-temporally constrained reconstruction. We evaluated five candidate (k, t) sampling strategies using a previously proposed gradient-echo stack-of-spiral sequence and a 3D constrained reconstruction with spatial and temporal penalties. Regularization parameters were chosen by expert readers based on qualitative assessment. We experimentally determined the effect of spiral angle increment and kz temporal order. The strategy yielding highest image quality was chosen as the proposed method. We evaluated the proposed and original 3D real-time MRI methods in 2 healthy subjects performing speech production tasks that invoke rapid movements of articulators seen in multiple planes, using interleaved 2D real-time MRI as the reference. We quantitatively evaluated tongue boundary sharpness in three locations at two speech rates. The proposed data-sampling scheme uses a golden-angle spiral increment in the kx -ky plane and variable-density, randomized encoding along kz . It provided a statistically significant improvement in tongue boundary sharpness score (P<.001) in the blade, body, and root of the tongue during normal and 1.5-times speeded speech. Qualitative improvements were substantial during natural speech tasks of alternating high, low tongue postures during vowels. The proposed method was also able to capture complex tongue shapes during fast alveolar consonant segments. Furthermore, the proposed scheme allows flexible retrospective selection of temporal resolution. We have demonstrated improved 3D real-time MRI of speech production using randomized, variable-density, stack-of-spiral sampling with a 3D spatio-temporally constrained reconstruction.

Method of Real-Time Wellbore Surface Reconstruction Based on Spiral Contour

A wellbore surface is an irregular surface structure. The distribution of points on the wellbore surface measured based on the drilling diameter is not uniform. Thus, the conventional modeling method based on a point cloud cannot satisfy the needs of real-time measurement updating and wellbore display. This study proposes a spiral profile method for drilling shaft surface reconstruction. Scattered data along the drilling diameter are measured, and an inverse distance weighting cylindrical space surface algorithm with iterative interpolation is used to obtain the spiral angle and pitch of a relatively homogeneous helical contour line along the surface of the shaft. Using sets of four adjacent points in the spiral, quadrilaterals are formed, and then all obtained quadrilaterals are used to form the wellbore inner surface structure. This method can further construct the outer surface spiral contour line to advance the quadrilateral surface to the spatial hexahedron structure. The caliper and gamma measurement data obtained from the calibrated wellbore were used to verify the real-time surface reconstruction and fusion while drilling. The homogenized reconstructed surface profile is more than 99.5% similar to the actual measurement. Proved by experiment and application, this method has very high real-time performance, and the three-dimensional stereo imaging wellbore with additional gamma attributes has good visual effects.

Design and experiment of vertical pneumatic fertilization system with spiral Geneva mechanism

In the traditional fertilization method, a large amount of fertilizer is applied, which causes congestion easily. It is not conducive to the sustainable development of agriculture. In this work, a vertical pneumatic fertilization system with a spiral Geneva mechanism was designed according to the operational requirements of variable-rate and smooth fertilization. The uniformity in discharging fertilizer with different spiral angles was simulated and analyzed by extended discrete element method (EDEM) based simulation software, from where the spiral angle of the fertilizer discharge wheel was determined to be 45°. The fertilization system includes a fertilizer apparatus with a spiral Geneva mechanism, whose optimal performance parameters were obtained from the bench experiment. The accuracy and uniformity of the fertilizer application system were taken as the evaluation indicators. The linear relationships of the discharged amount of fertilizer with the rotational speed and the opening of the fertilizer discharging wheel were verified by both static blowing fertilization and field experiments. The static blowing experimental results show that the discharged amount of fertilizer has a high linear correlation and accuracy with both the opening and rotational speed, and the highest correlation occurs with the rotational speed. The rotational speed and opening have significant effects on the discharged amount of fertilizer and the average coefficient of variation. The effect of the rotational speed was the most significant. According to the model obtained by multiple regression fittings, the optimal parameters were determined when the average coefficient of variation was small, the rotational speed was 15.9 r/min and the opening was 34.4 mm. Therefore, the purpose of precise fertilization can be achieved by adjusting the opening or rotational speed in a way to get the exact amount of fertilizer discharged as required by the corresponding crops. The field experiment showed that the variation coefficient of each fertilizer discharged decreases first and then increases with an increasing opening under different rotational speeds, which is consistent with the theoretical value. When the opening was 40 mm or 50 mm, the variation coefficient reached the minimum value, which is far less than the qualified index of 7.8%. In the static blowing experiment and the dynamic field experiment, the stability of the fertilizer discharging device can be significantly enhanced with the utilization of the pneumatic conveying fertilizer. This study can provide a theoretical reference for parameter selection and optimization of vertical spiral fertilization systems. Keywords: precision fertilization, fertilizer apparatus, variable rate technology, spiral Geneva mechanism, simulation analysis, performance experiment DOI: 10.25165/j.ijabe.20211404.6575 Citation: Chen H B, Zheng J F, Lu S J, Zeng S, Wei S L. Design and experiment of vertical pneumatic fertilization system with spiral Geneva mechanism. Int J Agric & Biol Eng, 2021; 14(4): 135–144.

Refining the mass estimate for the intermediate-mass black hole candidate in NGC 3319

Abstract Recent X-ray observations by Jiang et al. have identified an active galactic nucleus (AGN) in the bulgeless spiral galaxy NGC 3319, located just $14.3\pm 1.1$ Mpc away, and suggest the presence of an intermediate-mass black hole (IMBH; $10^2\leq M_\bullet/\textrm{M}_{\odot}\leq 10^5$ ) if the Eddington ratios are as high as 3 to $3\times10^{-3}$ . In an effort to refine the black hole mass for this (currently) rare class of object, we have explored multiple black hole mass scaling relations, such as those involving the (not previously used) velocity dispersion, logarithmic spiral arm pitch angle, total galaxy stellar mass, nuclear star cluster mass, rotational velocity, and colour of NGC 3319, to obtain 10 mass estimates, of differing accuracy. We have calculated a mass of $3.14_{-2.20}^{+7.02}\times10^4\,\textrm{M}_\odot$ , with a confidence of 84% that it is $\leq $ $10^5\,\textrm{M}_\odot$ , based on the combined probability density function from seven of these individual estimates. Our conservative approach excluded two black hole mass estimates (via the nuclear star cluster mass and the fundamental plane of black hole activity—which only applies to black holes with low accretion rates) that were upper limits of ${\sim}10^5\,{\textrm M}_{\odot}$ , and it did not use the $M_\bullet$ – $L_{\textrm 2-10\,\textrm{keV}}$ relation’s prediction of $\sim$ $10^5\,{\textrm M}_{\odot}$ . This target provides an exceptional opportunity to study an IMBH in AGN mode and advance our demographic knowledge of black holes. Furthermore, we introduce our novel method of meta-analysis as a beneficial technique for identifying new IMBH candidates by quantifying the probability that a galaxy possesses an IMBH.

Kontaktni napon kod helikoidnih konusnih zupčanika

Helical bevel gears have inclined or twisted teeth on a conical surface and the common types are skew, spiral, zerol, and hypoid bevel gears. However, this study does not include hypoid bevel gears. Due to the geometric complexities of bevel gears, commonly used methods in their design are based on the concept of equivalent or virtual spur gear. The approach in this paper is based on the following assumptions, a) the helix angle of helical bevel gears is equal to mean spiral angle, b) the pitch diameter at the backend is defined as that of a helical gear, and c) the Tredgold's approximation is applied to the helical gear. Upon these premises, the contact stress capacity of helical bevel gears is formulated in explicit design parameters. The new contact stress capacity model is used to estimate the contact stress in three gear systems for three application examples and compared with previous solutions. Differences between the new estimated results and the previous solutions vary from -3% and -11%, with the new estimates being consistently but marginally or slightly lower than the previous solution values. Though the differences appear to be small, they are significant because the durability of gears is strongly influenced by the contact stress. For example, a 5% reduction in contact stress may result in almost 50% increase in durability in some steel materials. The equations developed do not apply to bevel crown gears.

Global Spiral Density Wave Modes in Protoplanetary Disks: Morphology of Spiral Arms

Abstract We analyze two-armed global spiral density wave modes generated by gravitational instability in razor-thin, nonviscous, self-gravitating protoplanetary disks to understand the dependence of spiral arm morphology (pitch angle α and amplitude) on various disk conditions. The morphologies of the resulting spiral density wave modes closely resemble observations. Their pitch angles and pattern speeds are insensitive to the boundary conditions adopted. Gaussian disks exhibit more tightly wound spirals (smaller pitch angle) than power-law disks under the same conditions. We find that at a fixed disk-to-star mass ratio (M d /M *), the pitch angle increases with average Toomre’s stability parameter ( ) or average disk aspect ratio ( ). For a given , density wave modes with higher M d /M * have larger pitch angles, while the behavior reverses for a given . The interdependence between pitch angle and disk properties can be roughly approximated by , where c s is the sound speed. Our gravitational instability-excited spiral density waves can be distinguished from planet-launched spirals: (1) massive cool disks have spiral pitch angle falling with radius, while low-mass hot disks have spiral pitch angle rising with radius; (2) the profile of spiral amplitude presents several dips and bumps. We propose that gravitational instability-excited density waves can serve as an alternative scenario to explain the observed spiral arms in self-gravitating protoplanetary disks.

Multi-Objective Optimization of Structural Parameters for Rotary Flow Jetting Tool Based on Orthogonal Experiment

There is no precedent for the application of rotary flow jetting tool in the drainage gas recovery under gas wells. Based on the motion principles of jet flow and vortex flow, this paper designs a downhole rotary flow jetting tool, and verifies the feasibility of the tool through fluid simulation. Next, an indoor experiment device was established for drainage gas recovery with rotary flow jetting tool by the principle of similarity, and the structural parameters of the tool were subject to multi-objective optimization through orthogonal experiments. The optimized tool can achieve ideal rotary flow height and discharge volume. The results show that the proposed rotary flow jetting tool can effectively separate gas from liquid, and produce a rotary flow. The optimal structural parameters were determined as follows: the pitch diameter of spiral body is 45mm, the throat pipe length is 247mm, the spiral angle is 55°-60°, the spiral wing width is 4-6mm, and the nozzle diameter is 15-25mm. In addition, the number of side holes of the throat pipe has little effect on the jetting effect.

On the Diversity of Asymmetries in Gapped Protoplanetary Disks

Abstract Protoplanetary disks with large inner dust cavities are thought to host massive planetary or substellar companions. These disks show asymmetries and rings in the millimeter continuum caused by dust trapping in pressure bumps and potentially vortices or horseshoes. The origin of the asymmetries and their diversity remains unclear. We present a comprehensive study of 16 disks for which the gas surface density profile has been constrained by CO isotopologue data. First, we compare the azimuthal extents of the dust continuum profiles with the local gas surface density in each disk and find that the asymmetries correspond to higher Stokes numbers or low gas surface density. We discuss which asymmetric structures can be explained by a horseshoe, a vortex, or spiral density waves. Second, we reassess the gas gap radii from the 13CO maps, which are about a factor of 2 smaller than the dust ring radii, suggesting that the companions in these disks are in the brown dwarf (∼15–50 M Jup) or super-Jovian (∼3–15 M Jup) mass regime on eccentric orbits. This is consistent with the estimates from contrast curves on companion mass limits. These curves rule out (sub)stellar companions (q &gt; 0.05) for the majority of the sample at the gap location, but it remains possible at even smaller radii. Third, we find that spiral arms in scattered-light images are primarily detected around high-luminosity stars with disks with wide gaps, which can be understood by the dependence of the spiral arm pitch angle on disk temperature and companion mass.

Development and Dynamic Analysis of a Torsional Vibration Damping Tool for PDC Bit

It is generally recognized that the stick-slip motion of a polycrystalline diamond compact (PDC) bit is responsible for the low rate of penetration (ROP) and premature failure of the PDC bit when drilling in hard rock formations. To solve this problem, a torsional vibration damping tool was developed. A working principle model of the tool and a calculation model of the optimal spiral angle of the tool was established. The stability of the tool was analyzed, and the parameter range of spiral guideline thread stability was determined. The analysis revealed that the tool can automatically adjust the weight on the bit (WOB) and the rotary speed of the PDC bit through the spiral guide and the disc spring, which could suppress the torsional vibration of the PDC bit and convert part of the vibration load into cutting torque for rock breaking and thus to improve the rate of penetration (ROP). The optimal spiral angle of the tool is proportional to the axial stiffiless, bit diameter, and rock hardness of the drill string system and inversely proportional to the torsional stiffness of the drill string system and the reclining angle of the PDC bit. The stability of the tool is related to the spiral angle, length, and friction angle of the spiral guide. The tools were applied in test wells, and the results indicate that the torque fluctuations are significantly decreased and effectively extend the service life of the PDC bit. During the test process, the tool exhibits steady performance, the feasibility of the tool calculation model was verified. It is anticipated that the presented results will make such drilling a more feasible method for well services.

Deformation characteristics in 3D free-bending forming of complex spiral tubes

Free-bending is a novel bending technology suitable for tube and profile bending. It can achieve accurate bending of tubes or profiles with different bending radii without die. In current study, a new theoretical analysis of a spiral tube formed by 3D free-bending is proposed to reveal the relationship between the spiral tube and the parameters of free-bending forming technology. The results obtained from the proposed theoretical analysis were compared with those achieved from FE modelling and experimentation. The maximum error of forming was less than 7%, which verified the accuracy and the reliability of the proposed theoretical model. The forming limits of the spiral tubes based on 3D free-bending were explored. It was noticed that the spiral diameter was mainly influenced by the eccentricity and the distance between the center of the bending die and the front end of the guide mechanism in the Z–direction (distance A). Furthermore, the spiral diameter is inversely proportional to the eccentricity, and directly proportional to the distance A. In addition, the screw pitch is mainly influenced, and directly proportional to the spiral diameter and the single spiral circle swing angle of the spherical bearing.

Numerical simulation and experimental verification of stability on multi-cavity spiral cascade heat transfer system

In order to improve the insufficient effect of heat transfer in pyrolysis carbonization system and reveal the effects of velocity and temperature field of hot flue gas on heat transfer and stability in the biomass, the structure with rectangular groove combined with a spiral baffle is designed to form a multi-cavity spiral cascade heat transfer system. Numerical simulation and experimental verification of stability are carried on multi-cavity spiral cascade heat transfer system. The results show that the hot flue gas with high temperature flows fast at the inlet and outlet, while the flow speed is slow and stable in the cavity of heat transfer. The temperature of hot flue gas reaches the highest at the entrance, and decreases in the heat exchange chamber in a cascade. The spiral inclination angle of 35? and the itch of 1.2 m. The combustion of gas produced by pyrolysis of raw materials can meet the requirement of continuous and stable operation, when the temperature of monitor point 1, 3, 6, and 8 reaches 800?C, 530?C, 250?C, and 200?, respectively. The temperature of hot flue gas changes fluctuate in the range of 15?. The combustion of pyrolysis gas generated during the pyrolysis process of raw materials can ensure the continuous and stable operation of the equipment.

GASP XXIX – unwinding the arms of spiral galaxies via ram-pressure stripping

ABSTRACT We present the first study of the effect of ram pressure ‘unwinding’ the spiral arms of cluster galaxies. We study 11 ram-pressure stripped galaxies from GASP (GAs Stripping Phenomena in galaxies) in which, in addition to more commonly observed ‘jellyfish’ features, dislodged material also appears to retain the original structure of the spiral arms. Gravitational influence from neighbours is ruled out and we compare the sample with a control group of undisturbed spiral galaxies and simulated stripped galaxies. We first confirm the unwinding nature, finding that the spiral arm pitch angle increases radially in 10 stripped galaxies and also simulated face-on and edge-on stripped galaxies. We find only younger stars in the unwound component, while older stars in the disc remain undisturbed. We compare the morphology and kinematics with simulated ram-pressure stripping galaxies, taking into account the estimated inclination with respect to the intracluster medium (ICM) and find that in edge-on stripping, unwinding can occur due to differential ram pressure caused by the disc rotation, causing stripped material to slow and ‘pile up’. In face-on cases, gas removed from the outer edges falls to higher orbits, appearing to ‘unwind’. The pattern is fairly short-lived (&amp;lt;0.5 Gyr) in the stripping process, occurring during first infall and eventually washed out by the ICM wind into the tail of the jellyfish galaxy. By comparing simulations with the observed sample, we find that a combination of face-on and edge-on ‘unwinding’ effects is likely to be occurring in our galaxies as they experience stripping with different inclinations with respect to the ICM.

Effects of spiral and cone angles on drying characteristics and energy consumption of fluidized bed paddy dryer

The demand for energy has been increasing all over the world, necessitating the introduction of novel devices to work with lower energy consumption. Modern technologies used for paddy drying are one of such processes which consumes a substantial amount of energy. The present work introduces a device (passive spiral) to be incorporated in fluidized bed dryers which could considerably reduce energy consumption and enhance drying characteristics while providing better nutritional values and quality end product in terms of paddy drying. Two conical fluidized bed with various cone angles (5° and 10°) and a columnar fluidized bed (0° cone angle) are used for the study to investigate the performance of dryers with and without spiral which shows that energy consumptions could be considerably reduced with the incorporation of a spiral inside the conical fluidized dryer and least with 10° cone angle. The pressure drop across the dryers, drying characteristics, the total energy consumptions such as blower and thermal energy consumption, nutritional values and milling quality of drying products are investigated for these three dryers with and without spiral and results are compared. The experiments are performed with two different inlet air velocities (1.1 and 1.6 m/s), and three different inlet air temperatures (55, 60, and 65 °C) with 1–3 kg batch size of paddy as a bed inventory. It is observed that the time taken to reduce the moisture content in conical bubbling fluidized dryer having cone angle 10° is lesser than the other two dryers. The drying rate is also found to be faster with the use of a spiral inside the three dryers than without the spiral. Incorporation of spiral exhibits better drying characteristics in terms of milling quality. Conical fluidized bed dryer having larger cone angle (10°) consumes less energy than the conical fluidized bed dryer having smaller cone angle (5°) and conventional fluidized bed dryer (0°). A total of around 40% less energy of blower and heater was consumed when spiral was used.

Study of spiral path angle in pressure-swirl atomizer with spiral path

The purpose of this study was to investigate the effect of the number of spiral paths on the spray cone angle, discharge coefficient and droplet diameter in pressure-swirl atomizer with spiral paths using numerical and experimental methods. Initially, the injector was designed and manufactured based on some assumptions such as operating fluid type, pressure difference, spray cone angle and mass flow rate and then tested. Comparison of test results with design assumptions showed that mass flow rate and spray cone angle and discharge coefficient were 5%, 13.25% and 4% error, respectively. Then, numerical solution method was used for numerical investigation of the influence of geometric parameters. To simulate the two-phase flow, the fluid volume fraction model was used. The numerical solution of mass flow rate and spray cone angle and discharge coefficient showed 7.4%, 9.5% and 11.76% error, respectively. The results showed that the pressure-swirl atomizer with spiral paths has a conical shape and is hollow. Also, the total velocity and its components on the edge of the spray cone have the highest value. Investigations showed that at constant mass flow rate with increasing the torsion of spiral path, the total radial, axial and tangential velocities increased, which increased the spray cone angle and decreased the droplet diameter.

A study of high-speed joining method using spiral nails

• The high-speed joining method using the nail with spiral grooves was proposed in this study. • It was seen that the optimum angle of the spiral groove on the nail was 270° in the high-speed joining condition in this study. • If the nail has the optimum groove angle, the ultimate shear tension force of the proposed method was about twice higher than that of the blind rivets. • If the nail has the optimum groove angle, the ultimate cross tension force of the proposed method was almost the same as that of the blind rivets. A variety of materials have been used to assemble transportation equipment in order to realize both securement of high strength and weight reduction in recent years. In the manufacturing fields, various joining methods are used, and there are as many methods as material variations. Among those joining methods, mechanical joining can join without heating or melting materials. We have proposed a high-speed nailing method using a spiral nail in order to improve the joining strength in this study. The proposed method is characterized by spiral grooves provided on nails, which bite joined parts to improve joining strength. Using nails with several spiral groove angles, this study has verified effectiveness of the spiral groove angles of the nail and also revealed the mechanism of the method that affects joining strength. Incidentally the proposed method can joint dissimilar materials at high speed without supporting behind clamped plates. Since the nail has the spiral grooves, we can easily remove the nails by rotating the nail in the opposite direction. Therefore the method is suitable for recycling and maintenance.

The Statistical Properties of Spiral Arms in Nearby Disk Galaxies

Abstract We analyze 4378 nearby bright disk (S0 and spiral) galaxies selected from the Sloan Digital Sky Survey to characterize their spiral structure and systematically investigate the relationships between spiral arm properties (strength, pitch angle, and number) and the global properties of the host galaxies. This is to date the largest sample of galaxies with comprehensive measurements of spiral properties based on Fourier decomposition. We find that spiral pitch angle decreases (arms become more tightly wound) toward galaxies of earlier Hubble type, higher stellar mass, redder color, and greater degree of central concentration. The dependence of pitch angle on stellar mass is mainly driven by color, and for a given concentration, spiral arms are more tightly wound in redder galaxies. Spiral pitch angles show a bimodal distribution, peaking at φ = 12° ± 3.°4 and 23° ± 4.°3. Spiral arms weaken in galaxies of earlier type, redder color, and higher concentration, but for a given concentration, spiral arms become more prominent in more massive and bluer galaxies. We confirm that spiral arm strength loosely correlates with pitch angle, although the scatter in this relation is considerable and depends systematically on mass and color; for a given pitch angle, more massive or bluer galaxies have stronger arms. Galaxies of earlier Hubble type, higher mass concentration, or redder color have fewer spiral arms. Lastly, galaxies with stronger bars have fewer but stronger arms. We discuss the possible origins of these various relationships, which provide useful empirical guidance to theories of spiral structure. Depending on the galaxy, both the density wave and swing amplification mechanisms operate.

Lubrication effects on axisymmetric flow of a micropolar fluid by a spiraling disk

Advances in modern technology and extremely stringent demands for rotating elements of machines impose researchers on the need for the continuous development of improved lubricants to ensure the stability, safe operation, and reliability of various bearings. For operations at high speed and heavy load, modern bearings use lubricants containing high molecular weight polymer components. Such lubricants exhibit non-Newtonian rheological behavior. Power-law lubricant is widely used for the bearings and the industrial lubrication processes. This article is established to estimate the power-law lubrication effects on the Homann flow of a micropolar fluid past a disk with the spiraling motion. A lubrication layer of a non-Newtonian power-law lubricant with negligible thickness is applied between the disk rough surface and the bulk fluid. A new and very complex interfacial boundary condition is derived for the lubricated spiraling disk and is utilized to explore the impact of different flow parameters on the fluid velocity as well as the microrotation. Numerical results are computed for some quantities of physical interest, i.e., radial, azimuthal skin friction coefficients, and the wall shear stress are calculated for various values of the spiral angle, disk spiraling parameter, material parameter, and slip parameter. The addition of slip assists the radial velocity and opposes the azimuthal velocity. The radial velocity is enhanced by increasing the disk spiraling and spiral angle.