Disk Rotation Research Articles

Hydrodynamic Analysis of the Thickness Variation in a Solid Film Formed by a Spin Coating Process

The surface profile of the film formed by spin coating is experimentally investigated in this paper. The unavoidable wavy form at the surface was observed when the ultraviolet curable resin was used. In addition, the surface thickness variation was directly related to the viscosity, disk rotation speed, and disk size. Fluid dynamic theory with non-dimensional analysis was conducted to describe the surface profile after the spin coating process. It was found that the film had been thickened until the viscosity force and Coriolis force were balanced. The Coriolis force, however, also affected the flow instability during the spinning of the disk. The film thickness variation is successfully described by using the non-dimensional factors. In addition, the edge bump which is induced by hydraulic jump is expressed by the relation of power law of Ekman, Weber, and Reynolds numbers. In this paper, the thickness variation and edge bump position are expressed by using hydrodynamic theory. It is also reveals that the Coriolis force acts based on the magnitude of thickness variation, and the surface tension affects the edge bump position. The presented relationships will contribute further understanding of the spin coating process. The outcome of this paper supports the cost-effective productions of electronic microcircuits and solar cells.

Tribological Properties of Laminate Composite Brake Material for High-Speed Trains

In this article, a laminate composite brake material was prepared by powder metallurgy techniques and proposed for use in the high-speed train braking system. The pad was a double-layer structure composed of prefabricated tribofilm (PTF, oxide-based materials) and metal-based materials. The friction and wear behaviors of the novel friction material with different thicknesses of PTF layer against steel rotor disc were investigated using a TM-I type braking dynamometer under initial braking speeds (IBS) of 50–350 km/h. It was found that the PTF pad exhibited stable friction behavior and wear rate in a large range of IBS (50–250 km/h), meeting the requirements of high-speed trains. During braking, the friction film formed on the worn surface was closely related to the friction and wear behavior. The PTF promoted the formation of a protective friction film, which provided a larger and flatter surface than that of metal-based materials. A relatively stable friction behavior and wear rate were maintained when the worn surface was covered with friction film.

Numerical and Experimental Analysis for the Dynamics of Flawed–Machining Rod–Disk Rotor with Inner Misalignment

The nonlinear dynamic effects of the misalignment between inner disks in a flawed–machining rod–disk rotor is studied. Non–uniform stress distribution due to inner misalignment is obtained based on 3D static solution. The concomitant unbalances, including constant mass eccentricity and speed–variant rotor bending, are taken into account in the nonlinear dynamics. The dynamic results show that rotor bending leads to stability reduction and vibration growth. There is a distinctive feature in that the rotor’s vibration goes up again after critical speed. The maximum allowable inner misalignment is obtained according to its stability boundaries. An uneven tightening method is also presented to reduce adverse effects when the inner misalignment exists. Moreover, an experiment is designed to measure the vibration characteristics for the rod–disk rotor bearing system with inner misalignment. The results show that the theoretical result of vibration amplitude of the flawed rod–rotor bearing system is basically consistent with the experimental value. It is also found that the precise rotor performs the periodic motion, but the flawed rod–disk rotor exhibits the period–doubling orbit. This phenomenon proves that the flawed rod–disk rotor loses stability more easily than the precise rotor due to inner misalignment. However, the amplitude of harmonic frequency components for the precise rod–disk rotor system is obviously larger than the flawed rod–disk rotor system with inner misalignment. The peak value of the vibration amplitude increases when the inner misalignment becomes larger. On the whole, this work presents numerical and experimental analysis to study the dynamics of flawed-machining rod–disk rotor with inner misalignment. It also establishes the relationship between centration precision and dynamic features.

Acoustoelastic Modes in Rotor-Cavity Systems: An Overview on Frequency Shift Effects Supported with Measurements

With an increase in fluid densities in centrifugal compressors, fluid-structure interaction and coupled acoustoelastic modes receive growing attention to avoid machine failure. Besides the vibrational behavior of the impeller, acoustic modes building up in the side cavities need to be understood to ensure safe and reliable operation. In a coupled system, these structure and acoustic dominant modes influence each other. Therefore, a comprehensive overview of frequency shift effects in rotor-cavity systems is established based on findings in the literature. Additionally, experimental results on coupled mode pairs in a rotor-cavity test rig with a rotating disk under varying operating conditions are presented. Measurement results for structure dominant modes agree well with theoretical predictions. The development of a forward and a backward traveling wave is demonstrated for each mode in case of disk rotation. Conducted experiments reveal the occurrence of weakly and strongly coupled mode pairs as frequency shifts are observed that cannot solely be explained by “uncoupled mode effects”, such as the added mass, speed of sound, and stiffening effect, but indicate an additional coupling effect. However, the hypothesis of a bigger frequency shift for stronger coupled modes cannot be corroborated consistently. Only for the strongly coupled four nodal diameter mode pair in the “wide cavity” setup, a coupling effect is clearly visible in the form of mode veering.

The Physical Properties of the SVS 13 Protobinary System: Two Circumstellar Disks and a Spiraling Circumbinary Disk in the Making

We present Very Large Array (VLA) and Atacama Large Millimeter/submillimeter Array (ALMA) observations of the close (0.″3 = 90 au separation) protobinary system SVS 13. We detect two small circumstellar disks (radii ∼12 and ∼9 au in dust, and ∼30 au in gas) with masses of ∼0.004–0.009 M ☉ for VLA 4A (the western component) and ∼0.009–0.030 M ☉ for VLA 4B (the eastern component). A circumbinary disk with prominent spiral arms extending ∼500 au and a mass of ∼0.052 M ☉ appears to be in the earliest stages of formation. The dust emission is more compact and with a very high optical depth toward VLA 4B, while toward VLA 4A the dust column density is lower, allowing the detection of stronger molecular transitions. We infer rotational temperatures of ∼140 K, on scales of ∼30 au, across the whole source, and a rich chemistry. Molecular transitions typical of hot corinos are detected toward both protostars, being stronger toward VLA 4A, with several ethylene glycol transitions detected only toward this source. There are clear velocity gradients, which we interpret in terms of infall plus rotation of the circumbinary disk, and pure rotation of the circumstellar disk of VLA 4A. We measured orbital proper motions and determined a total stellar mass of 1 M ☉. From the molecular kinematics, we infer the geometry and orientation of the system, and stellar masses of ∼0.26 M ☉ for VLA 4A and ∼0.60 M ☉ for VLA 4B.

The effects of nanoparticle aggregation and radiation on the flow of nanofluid between the gap of a disk and cone

The heat transfer in three-dimensional coordinates is the main focus of the present article. The cone-disk (CND) apparatus is presumed to include a stationary cone (SCN) and a rotating disk (RTD), or counter-rotating, or both of them co-rotating, along with Titanium dioxide-ethylene glycol-based nanofluid. The accommodative impact of nanopaprticles aggregation and thermal radiation is considered in the modelling equations for the flow pattern available in the literature. The modelling equations are converted into ordinary differential equations (ODEs) using similarity transformations. The behaviour of flow profiles is readily understood by employing the Runge Kutta Fehlberg fourth fifth-order (RKF45) method and the shooting approach, which is strategized and explained using graphs. The outcomes reveal that the dynamics of flow with nanoparticles aggregation case shows better-quality heat transport for increased values of radiation parameter. Furthermore, the fluid flow with aggregation shows the developed heat transfer rate at cone surface for increased values of radiation parameter.

Citric acid production using rotating biodisc reactor (RBR)

Citric acid is one of the most remarkable industrial goods fabricated by industrial fermentation using filamentous fungus. When Aspergillus niger, a filamentous fungus, is produced under suitable conditions, high amounts of citric acid are obtained. This study aims to explain the citric acid synthesis studied in a biodisc reactor using A. niger. Various physiological parameters have been investigated in order to determine the optimum citric acid synthesis in biodisc reactor. Optimum incubation time was found to be as 168 hours in the study. The optimum value of the incubation temperature was determined to be 30°C. The optimum value of the initial pH was found to be 3.8. Optimum citric acid synthesis occurred when the disc rotation speed was 2 rpm. In addition, the optimum value of the initial sugar (sucrose) concentration was determined to be 20%. In a semi-continuous production study with the renewal of the medium after a certain incubation period, it was determined that the citric acid yield increased approximately 3 times compared to the batch system. As a result, the highest value of citric acid was determined as 67.65 g/L.

Dynamic and fluctuation properties of a graphene disk levitated by a diamagnetic force in air

A graphene disk can be levitated above a magnet by a repulsive force arising from their diamagnetic interaction if the product of the magnetic field and its gradient is sufficiently large. The diamagnetic force also causes the rotation of the graphene disk because of the strong anisotropy of the magnetic permeability of graphene; thus a motion of centroid and rotation are considered by solving simultaneous Langevin equations. Furthermore, the dependence of a fluctuations of the position and angle of the levitated graphene disk on the size and temperature is also explained.

ИССЛЕДОВАНИЕ ПАРАМЕТРОВ ВЗАИМОДЕЙСТВИЯ СЕМЯН С ЕМКОСТНЫМ ДАТЧИКОМ ВЫСЕВА

. A promising direction for the development of precision seeding drills is their electrification with the development of a control system for the rotation of the disc of the seeding apparatus, as well as the improvement of the seeding control system with the subsequent development of an algorithm for automatic control and regulation of the position of the puller doubles. The interaction of seeds with a capacitive seeding sensor is necessary to study and determine the duration of the flight of one seed through its sensitive elements to ensure high-quality and reliable operation of the automatic control system for the position of the doubles puller. The research was carried out with seeds of various crops: soy (variety “Lisbon”), corn (variety “Falcon”), lupin (variety “Delta”), sugar beet for experiments (fraction: 3.50–4.75). The values of the time of flight of seeds through the sensitive elements of the seeding sensor were determined with an accuracy of one millisecond in the course of laboratory studies and displayed on the display in the form of a graph, stored in the computer's memory and then processed by methods of mathematical statistics. Data on the time of flight of seeds through the capacitive sensor, which are for: soybean - from 11 to 13 ms, lupine - from 11 to 14 ms, sugar beet - from 7 to 9 ms, corn - from 12 to 14 ms were obtained from the results of research. They practically do not change in the operating speed range of the sowing unit (sowing disc rotation frequency 20 - 60 rpm), and can be taken as the time of flight of one seed in further calculations.The obtained data will allow to determine more detailed information about the operation of the sowing unit (skips, twins, damaged seeds), which will significantly increase the functionality of the seeding control systems used.

Disc cloaking: Establishing a lower limit to the number density of local compact massive spheroids/bulges and the potential fate of some high-z red nuggets

ABSTRACT The near-absence of compact massive quiescent galaxies in the local Universe implies a size evolution since z ∼ 2.5. It is often theorized that such ‘red nuggets’ have evolved into today’s elliptical (E) galaxies via an E-to-E transformation. We examine an alternative scenario in which a red nugget develops a rotational disc through mergers and accretion, say, at 1 ≲ z ≲ 2, thereby cloaking the nugget as the extant bulge/spheroid component of a larger, now old, galaxy. We have performed detailed, physically motivated, multicomponent decompositions of a volume-limited sample of 103 massive ($M_*/\rm M_{\odot } \gtrsim 1\times 10^{11}$) galaxies within 110 Mpc. Many less massive nearby galaxies are known to be ‘fast-rotators’ with discs. Among our 28 galaxies with existing elliptical classifications, we found that 18 have large-scale discs, and two have intermediate-scale discs, and are reclassified here as lenticulars (S0) and elliculars (ES). The local spheroid stellar mass function, size–mass diagram and bulge-to-total (B/T) flux ratio are presented. We report lower limits for the volume number density of compact massive spheroids, nc, Sph ∼ (0.17–$1.2) \times 10^{-4}\, \rm Mpc^{-3}$, based on different definitions of ‘red nuggets’ in the literature. Similar number densities of local compact massive bulges were reported by de la Rosa et al. using automated two-component decompositions and their existence is now abundantly clear with our multicomponent decompositions. We find disc-cloaking to be a salient alternative for galaxy evolution. In particular, instead of an E-to-E process, disc growth is the dominant evolutionary pathway for at least low-mass ($1\times 10^{10}\lt M_*/\rm M_{\odot } \lessapprox 4 \times 10^{10}$) red nuggets, while our current lower limits are within an alluring factor of a few of the peak abundance of high-mass red nuggets at 1 ≲ z ≲ 2.

Effects of the duct on the vibro-acoustic characteristics of the pump-jet–shaft–submarine system under pump-jet excitation

The characteristics of the distributed pressure on duct induced by rotor and its effects on the vibro-acoustic response of the coupled pump-jet – shaft – submarine system are investigated. Firstly, the pulsating pressure on the duct and the rotor of the pump-jet is computed by numerical approaches of computational fluid dynamics (CFD). Then, the pulsating pressures on CFD mesh are mapped to structural mesh based upon radical basis function to apply them on the pump-jet to calculate the vibro-acoustic responses of the coupled pump-jet – shaft – submarine system by coupled finite element method (FEM) and direct boundary element method (BEM). Finally, the effects of the duct (including the distributed pressure on it as well as the vibration transmission characteristics) on sound radiation are investigated. The results show that the distributed pressure on the inner surface of the duct near rotor disk is a kind of traveling wave pressure, which is tonal at blade passing frequency and its harmonics. The main contribution of the unsteady distributed pressure on the duct to the underwater sound radiation mainly reflects at blade passing frequency (BPF), as well as the duct modes and the hull bending modes that exhibit large deformation at the locations for the stator blades attached to.

Advanced analysis of fan noise measurements supported by theoretical source models

With the objective to improve the understanding of the dominant fan noise source mechanisms, a comprehensive experimental study was conducted at a low speed fan test rig. The aerodynamic fan map as well as the acoustic characteristics of the fan was measured for a new blade integrated disk (Blisk) rotor with systematic variation of the shaft speed and throttling. The interpretation of the results is supported by simulations of the experiment with a physics-based analytical in-house tool for fan noise prediction. For the acoustic measurements, an array of wall-flushed microphones was used in the inlet section. By means of radial mode analysis techniques, the broadband and tonal sound powers are calculated for each operating point. In the obtained comprehensive database, systematic variations of the tonal and broadband sound power with the flow rate are found. These patterns can only partly be correlated to the varying incidence angle of the rotor blades. Comparing the mode distributions of the measured noise and the analytical models then allows conclusions on the predominant noise sources of rotor–stator interaction and inflow-rotor interaction.

Buffer effect of turbine rim cavity on hot gas ingestion

The rotor disc in the gas turbine creates a pump effect that entrains the fluid near it to radially outward. The hot gas in the mainstream enters the stator–rotor wheel space to maintain mass balance, leading to gas ingestion. The mechanism of the gas ingestion, and the spoiling effect of purge flow on mainstream, and the formation and transform mechanism of the source and core fluid regions in rotor–stator system are revealed in this research. In addition, a radial–radial–axial clearance rim seal (RRACS) is proposed to form a new stator–stator cavity to buff the ingestion flow. Numerical results show that the minimum mass flow rate for seal of the RRACS is 15.76% of the standard axial clearance rim seal.

Local hybrid Allen-Cahn model in phase-field lattice Boltzmann method for incompressible two-phase flow.

For simulating incompressible two-phase fluid flows, several phase-field lattice Boltzmann (LB) methods based on the local Allen-Cahn (AC) equation have been intensively proposed in recent years. We present a local hybrid AC model for the phase-field LB method. In the proposed model, the local and nonlocal AC equations are linearly combined using a local weight assigned in the interface or bulk phase regions individually. Five numerical problems, namely diagonal translation, Zalesak's disk rotation, static bubble, two bubbles of different radii, and Rayleigh-Taylor instability, are simulated for validation. The numerical results agree well with the analytical solutions or available previous results. Additionally, the numerical dispersion and the coarsening phenomenon are considerably suppressed in the proposed model. Finally, the performance of the proposed model is validated by conducting a drainage simulation in porous media and compared with the global hybrid AC model.

Blood-Coated Sensor for High-Throughput Ptychographic Cytometry on a Blu-ray Disc.

The Blu-ray drive is an engineering masterpiece that integrates disc rotation, pickup head translation, and three lasers in a compact and portable format. Here, we integrate a blood-coated image sensor with a modified Blu-ray drive for high-throughput cytometric analysis of various biospecimens. In this device, samples are mounted on the rotating Blu-ray disc and illuminated by the built-in lasers from the pickup head. The resulting coherent diffraction patterns are then recorded by the blood-coated image sensor. The rich spatial features of the blood-cell monolayer help down-modulate the object information for sensor detection, thus forming a high-resolution computational biolens with a theoretically unlimited field of view. With the acquired data, we develop a lensless coherent diffraction imaging modality termed rotational ptychography for image reconstruction. We show that our device can resolve the 435 nm line width on the resolution target and has a field of view only limited by the size of the Blu-ray disc. To demonstrate its applications, we perform high-throughput urinalysis by locating disease-related calcium oxalate crystals over the entire microscope slide. We also quantify different types of cells on a blood smear with an acquisition speed of ∼10,000 cells per second. For in vitro experiments, we monitor live bacterial cultures over the entire Petri dish with single-cell resolution. Using biological cells as a computational lens could enable new intriguing imaging devices for point-of-care diagnostics. Modifying a Blu-ray drive with the blood-coated sensor further allows the spread of high-throughput optical microscopy from well-equipped laboratories to citizen scientists worldwide.

Design of Wireless Charging Coils for Aero-engine Telemetry Information Transmission System

Abstract In order to meet the need of non-contact transmission of aero-engine telemetry information, first of all, a rotor disk and a stator disk suitable for near field communication are designed in this paper, then, the coil design of wireless charging system suitable for high centrifugal force load is carried out. The designed single charging coil can charge two receiving coils at the same time. In order to eliminate the influence of aluminum alloy rotor disk and stator disk on charging performance, concave ferrite slots are installed on rotor disk and stator disk respectively to shield charging coil and receiving coil. The designed charging coils are fabricated and integrated with rotor disk and stator disk respectively. Finally, the designed charging coil and receiving coils are connected into the charging system for testing. The test results show that the charging coil and receiving coils are completely matched with the charging circuit and receiving circuit, and their performance can fully meet the use requirements of aeroengine telemetry information transmission system.

Design of Transmitting Antenna for Aero-engine Telemetry Information Transmission System

Abstract The demand of aero-engine for non-contact telemetry information transmission is very urgent. Based on the analysis of the characteristics of aero-engine telemetry information transmission system, the rotor disk and stator disk suitable for near-field communication under high centrifugal load are designed in this paper. In order to ensure the stable transmission of telemetry information under large angular displacement between rotor disk and stator disk, two circular arc-shaped dipole antennas are designed to be symmetrically installed on rotor disk for telemetry information transmission. The designed pair of arc-shaped dipole antennas are fabricated and measured. The measurement results show that the two transmitting antennas resonate at 2.19GHz and 2.27GHz respectively, and their impedance bandwidth of -10dB is 35MHz and 34mhz respectively. In their operating frequency band, the isolation between them is greater than 38dB, and their performance fully meets the needs of aeroengine telemetry information transmission.

Study on the effect of transition process on rotor hovering simulation

Hovering is one of important statuses to evaluate the aerodynamic performance of a rotor. With the development of the computer technology and CFD technique, the numerical methods based on the first principle are usually employed to evaluate the hovering performance of the rotor. The transition process will evidently affect the results from the RANS-based numerical simulations in some steady cases for the fixed wing aircrafts, which should be taken into consideration in the design process. But it's not clear whether the transition process would affect the numerical results for the rotor simulation. To provide the reference in designing and evaluating the rotorcraft, the effect of the transition process in the rotor simulation needs to be discussed further. The PSP rotor proposed by NASA is calculated using the in-house solver based on the overset grid in this paper. Simulations are performed with fully turbulent model as well as the transitional model and the results are compared to the experimental data. The results prove the superior ability to simulate the flow around a hovering rotor of the in-house solver. The relative errors of the numerical results are under 5%. The range of the laminar flow on the blade is proportional to the rotor thrust, which causes a higher Figure of Merit in transition simulation than the fully turbulent simulation. The sectional pressure distribution and torque distribution along the blade apparently suffer from the transition process, which doesn't affect the thrust distribution along the blade and the blade vortex wake flow under the rotor disk. An obvious flow separation on the surface of the blade can be observed in the transition simulation compared to the fully turbulent simulation.

Stellar feedback in M83 as observed with MUSE

Context. Young massive stars inject energy and momentum into the surrounding gas, creating a multi-phase interstellar medium (ISM) and regulating further star formation. The main challenge of studying stellar feedback proves to be the variety of scales spanned by this phenomenon, ranging from the immediate surrounding of the stars (H II regions, 10s pc scales) to galactic-wide kiloparsec scales. Aims. We present a large mosaic (3.8 × 3.8 kpc) of the nearby spiral galaxy M83, obtained with the MUSE instrument at ESO Very Large Telescope. The integral field spectroscopy data cover a large portion of the optical disk at a resolution of ∼20 pc, allowing the characterisation of single H II regions while sampling diverse dynamical regions in the galaxy. Methods. We obtained the kinematics of the stars and ionised gas, and compared them with molecular gas kinematics observed in CO(2-1) with the ALMA telescope array. We separated the ionised gas into H II regions and diffuse ionised gas (DIG) and investigated how the fraction of Hα luminosity originating from the DIG (fDIG) varies with galactic radius. Results. We observe that both stars and gas trace the galactic disk rotation, as well as a fast-rotating nuclear component (30″ ≃ 700 pc in diameter), likely connected to secular processes driven by the galactic bar. In the gas kinematics, we observe a stream east of the nucleus (50″ ≃ 1250 pc in size), redshifted with respect to the disk. The stream is surrounded by an extended ionised gas region (1000 × 1600 pc) with enhanced velocity dispersion and a high ionisation state, which is largely consistent with being ionised by slow shocks. We interpret this feature as either the superposition of the disk and an extraplanar layer of DIG, or as a bar-driven inflow of shocked gas. A double Gaussian component fit to the Hα line also reveals the presence of a nuclear biconic structure whose axis of symmetry is perpendicular to the bar. The two cones (20″ ≃ 500 pc in size) appear blue- and redshifted along the line of sight. The cones stand out for having an Hα emission separated by up to 200 km s−1 from that of the disk, and a high velocity dispersion ∼80–200 km s−1. At the far end of the cones, we observe that the gas is consistent with being ionised by shocks. These features had never been observed before in M83; we postulate that they are tracing a starburst-driven outflow shocking into the surrounding ISM. Finally, we obtain fDIG ∼ 13% in our field of view, and observe that the DIG contribution varies radially between 0.8 and 46%, peaking in the interarm region. We inspect the emission of the H II regions and DIG in ‘BPT’ diagrams, finding that in H II regions photoionisation accounts for 99.8% of the Hα flux, whereas the DIG has a mixed contribution from photoionisation (94.9%) and shocks (5.1%).

Improving the vertical solar distiller performance using rotating wick discs and integrated condenser

Freshwater is one of the most essential needs of society. Due to the limited amount of potable water on Earth, guaranteeing the supply of clean water to society is a major challenge. By utilizing abundant sunshine, solar still could be utilized to provide the necessary amount of drinking water in remote locations. The issue of restricted daily production inspires researchers to investigate novel ways for enhancing the thermal performance of desalination techniques while lowering expenses. In this work, the scholars improved a unique distillation method related to solar stills. The authors presented a novel improvement to the vertical distiller design to enhance the exposure area while decreasing the thickness of the water layer as much as possible. Thus, two rotational discs (flat type) covered with wick were integrated into the vertical distiller basin at 1.5 rpm and 5 cm water depth. Furthermore, providing vacuum via a fan with an external condenser. Besides, various rotating speeds (from 400 to 2000 rpm) were tested to determine the perfect fan speed that provides the maximum yield. The experimental findings revealed that the modified vertical distiller produced more pure water than the conventional distiller. Moreover, the rotation of wick discs and vacuum fan enhanced the yield of distillers enormously. Besides, the highest distiller performance was obtained at 1.5 rpm (wick disc speed) and 1600 rpm (fan speed, 10 min ON, and 10 min OFF). Moreover, the daily freshwater output was 19.1 L/m2 day for MDSVD without the fan and 23.65 L/m2 day for MDSVD with the fan. So, the yield of MSSVD without/with vacuum fan was improved by 548.65% and 660.45%, respectively, over that of CTD. The best thermal efficacy for MDSVD without/with vacuum fan was 77.47% and 84.05%, respectively. Lastly, the average cost of freshwater was 0.021, 0.0177, and 0.0164 $/L for CTD, MDSVD without/with vacuum fan, respectively.