Rotation Rate Research Articles

Anodic Hydrogen Generation from Benzaldehyde on Au, Ag, and Cu: Rotating Ring-Disk Electrode Studies

Abstract Aldehydes are selectively oxidized to carboxylates on group 11 metals at low potentials (<0.4 V vs. RHE) in alkaline media. This process can occur by a pathway that generates H2 gas from the aldehyde, known as electro-oxidative dehydrogenation (EOD) or anodic hydrogen production. The EOD process occurs with transfer of only one electron per aldehyde, whereas typical oxidation with discharge of hydrogen to form water is a two-electron process. Here, we study the catalytic activity and selectivity toward H2 of Au, Ag, and Cu electrodes using benzaldehyde with rotating disk and ring-disk electrode (RDE/RRDE) techniques. The average number of electrons per benzaldehyde molecule obtained via H2 detection by RRDE agrees with that obtained via Koutecký-Levich analysis conducted at various rotation rates. We find that Au and Ag have much higher H2 and benzoate formation rates than Cu, but that Cu can perform the reaction at about 0.2 V lower overpotentials. On all three materials, benzaldehyde oxidation has high selectivity to anodic H2 (one-electron pathway) below ~0.5 V vs. RHE, but, with increasing potential, the selectivity shifts to H-oxidation forming water (two-electron pathway).

High Data Rate MWD Mud Pulse Telemetry – From Mysteries to Discovery

Our new approach to MWD mud pulse telemetry offers significant increases over conventional data rates. Using waveguide acoustics, we show that common drilling communications channels support carrier frequencies exceeding several hundred Hertz. Such signals are prone to attenuation over large drillpipe distances. Low power, self-spinning “turbosirens” are designed, providing high torque and rotation rate performance at all flow rates without electric or hydraulic motor drives. The sirens rotate, drawing only on the kinetic energy of the mud, like flapping flags oscillating in wind. Our turbosirens are minimally affected by LCM jamming. Turbine and siren rotor components ride freely along longitudinal trenches built into rotating shafts. Both magically float into the oncoming mud as it slows down, thus, widening all gap spaces and freeing any trapped debris even as both travel opposite to the mud flow. In addition, “turbosirens in series” signal superposition, drawing on constructive wave interference, offers strong pressure signals at high frequencies without mechanical complexity. Rapid modulations are possible, also without motor drive, relying on rapidly acting electro-magneto rheological brakes powered by turbosirens. To take advantage of hardware capabilities, “Intelligent i FSK” telemetry, or Frequency Shift Keying creates clean signals without the ambiguous wave reflections found with PSK and randomized time shifts. Frequency pairs are not selected arbitrarily, but chosen from “neighboring pressure peaks and valleys” in frequency space as determined from bottomhole assembly waveguide Fourier analysis. Finally, surface signal processing and reflection removal are facilitated with time delay and differential equation algorithms. For deep wells where multiple drill pipe reflections are unlikely, analytical solutions for both are obtained assuming single reflections which do not involve windowing challenges and complicated digital filter design. Software and hardware developments patented, published and validated over the years, are integrated, refined and readied for controlled field tests.

Enhancing optical absorbance and accelerating rotational speed in molecular motors through oriented external electric fields

Accelerating the rotational speed of light-driven molecular motors is among the foremost concerns in molecular machine research, as this speed directly influences the performance of a motor. Controlling the motor’s rotation is crucial for practical applications, and using an oriented external electric field (OEEF) represents a feasible method to achieve this objective. We have investigated the impact of an OEEF on the optical and kinetic properties of a novel π-donor/acceptor di-substituted molecular motor, R2,3-(NH2, CHO). We employed density functional theory (DFT) and time-dependent DFT methods to analyze the electronic excitation and thermal isomerization behavior. Our results demonstrate that the absorption wavelength, absorption efficiency of the motor, and rate constant of the thermal isomerization reaction can be adjusted by applying OEEFs, which are predictable based on the dipole moment and polarizability of the molecules under consideration. In particular, we observed a shift in the absorption wavelength toward longer ranges, an enhancement in light absorption intensity, and an acceleration in the rotation rate when applying a weak positive directional external electric field to the R2,3-(NH2, CHO) motor. In summary, this theoretical study highlights the potential of OEEFs for improving the performance of molecular motors.

Differential Rotation of Individual Sunspots and Pores

The analysis of the rotation rate of individual sunspots and pores was performed according to the data from the processing of observations by the Solar Dynamics Observatory/Helioseismic and Magnetic Imager in the period 2010–2024. Sunspots stood out in the images in the continuum. To accurately track the spots, we processed five images for each day. To determine the polarity of the magnetic field, we superimposed the contours of sunspots on observations of magnetic fields at the same time. This made it possible to track the movement of more than 210,000 individual sunspots and pores. It is found that the rotation rate is influenced by the rotation rate of the solar atmosphere and the systematic proper motions of the spots. Sunspots and pores of the leading polarity have a rate of meridional movement ≈2.4% faster than spots of the trailing polarity. We also found that regular sunspots, which have umbrae and penumbrae, rotate ≈1.5% faster than solar pores, in which penumbrae are absent. The dependence of the rotation rate on the area is found. For sunspots with an area of S > 10 μhm, the rotation rate is practically independent of the area. Small sunspots, with an area of S < 10 μhm, rotate ≈1.7% more slowly.

Numerical study of wake flow across two circular cylinders in tandem arrangement with high rotation speed

Flow behind a bluff body is marked with unstable wake pattern eventually impacting the forces acting on the body, which can be actively controlled by rotation. When multiple rotating bluff bodies are placed in close proximity, the wake flow and resulting forces are significantly affected by the mutual flow interaction, necessitating detailed analysis for practical applications. In this vein, this study investigates the variation in wake flow across two circular cylinders, placed in a tandem arrangement, for both co-rotation and counter-rotation configurations. Two-dimensional numerical simulations are performed at a low Reynolds number of 100 for three gap ratios of L/D = 1.5, 2, and 4, where L and D are the center-to-center distance between the cylinders and the cylinder diameter, respectively. The non-dimensional rotation rate is varied from 0 to 6 for the co-rotation configuration and the range is extended till 15 for counter-rotation configuration to capture the secondary instability regime of the system. Flow regimes and force coefficients are analyzed to qualitatively and quantitatively map the overall system behavior, respectively. The flow regimes observed for different rotation rates and L/D are noticed to be different combinations of the flow regimes observed for a single rotating cylinder. Irrespective of the co-rotation or counter-rotation configuration, the dominant frequency of secondary vortex shedding for both upstream and downstream cylinder is noticed to be same, indicating that either a single vortex is shed from the system or a synchronized vortex pair is shed with one vortex from each cylinder. Compared to the co-rotating cylinders, counter-rotating cylinders demonstrate predominant inclination toward steady flow behavior over majority of the studied rotation rates.

Insight into drilling performance parameters for in-situ detection of lithological transition

In order to examine the rock dependence on drilling performance parameters, such as torque and rate of penetration (ROP), we conducted laboratory drilling experiments using mafic and ultramafic rocks from the Oman ophiolite and the Horoman Complex. Serpentinized peridotite shows approximately twice the ROP (dry conditions: 2.95 ~ 3.85, wet conditions: 8.25 ~ 10.3 × 10−5 m/min) compared to that of peridotite and mafic samples (dry conditions: 4.75 ~ 6.90, wet conditions: 14.5 ~ 18.3 × 10−5 m/min) under both dry and wet conditions. This result is likely due to the reduction in fracture strength associated with serpentinization. We compared the laboratory results of drilling parameters with in situ data obtained from IODP Expedition 360 drilling of gabbro and Expedition 399 drilling of serpentinized peridotite, using the equivalent strength method to normalize ROP to the given rotation rate and torque. The calculation results show that the normalized ROP for the serpentinized peridotite formation was systematically higher than that for the gabbro layer, which is in agreement with our experimental results. We propose that the in situ drilling performance parameters can be used to detect the lithological transitions, such as serpentinite.

On the origin of circular rolls in rotor-stator flow

Rotor-stator flows are known to exhibit instabilities in the form of circular and spiral rolls. While the spirals are known to emanate from a supercritical Hopf bifurcation, the origin of the circular rolls is still unclear. In the present work we suggest a quantitative scenario for the circular rolls as a response of the system to external forcing. We consider two types of axisymmetric forcing: bulk forcing (based on the resolvent analysis) and boundary forcing using direct numerical simulation. Using the singular value decomposition of the resolvent operator the optimal response is shown to take the form of circular rolls. The linear gain curve shows strong amplification at non-zero frequencies following a pseudo-resonance mechanism. The optimal energy gain is found to scale exponentially with the Reynolds number $Re$ (for $Re$ based on the rotation rate and interdisc spacing $H$ ). The results for both types of forcing are compared with former experimental works and previous numerical studies. Our findings suggest that the circular rolls observed experimentally are the effect of the high forcing gain together with the roll-like form of the leading response of the linearised operator. For high enough Reynolds number it is possible to delineate between linear and nonlinear responses. For sufficiently strong forcing amplitudes, the nonlinear response is consistent with the self-sustained states found recently for the unforced problem. The onset of such non-trivial dynamics is shown to correspond in state space to a deterministic leaky attractor, as in other subcritical wall-bounded shear flows.

Image motion compensation control method for the dynamic scan and stare imaging system

The main function of the dynamic scan and stare imaging system is to quickly and continuously search a large area and perform high-resolution imaging. To eliminate image motion during the scanning process, this paper proposes an image motion compensation control method with dual-channel control. First, an improved model-assisted active disturbance rejection control is proposed, in which an auxiliary model is integrated into the algorithm to improve the control accuracy and response speed of the rotation rate of the platform. Second, a fast steering mirror (FSM) is introduced into the control system to compensate for the scanning speed and multiple disturbances. By adopting the amplitude frequency characteristics of the tracking differentiator, a parallel tracking differentiator filter is designed to suppress the interference of gyroscope noise on the FSM. When the system is disturbed by multiple frequency disturbances, the residual error of the image motion compensation is less than the spatial angular resolution of one pixel through the dual-channel stable control of the platform and the FSM. In the scan imaging experiment results, the average value of the grayscale variance function for the compensated images is close to 90% that of the static reference images.

Ages of Stars and Planets in the Kepler Field Younger than Four Billion Years

Recent analyses of FGK stars in open clusters have helped clarify the precision with which a star’s rotation rate and lithium content can be used as empirical indicators for its age. Here we apply this knowledge to stars observed by Kepler. Rotation periods are drawn from previous work; lithium is measured from new and archival Keck/HIRES spectra. We report rotation-based ages for 23,813 stars (harboring 795 known planets) for which our method is applicable. We find that our rotational ages recover the ages of stars in open clusters spanning 0.04–2.5 Gyr; they also agree with ≳90% of the independent lithium ages. The resulting yield includes 63 planets younger than 1 Gyr at 2σ, and 109 with median ages below 1 Gyr. This is about half the number expected under the classic assumption of a uniform star formation history. The age distribution that we observe, rather than being uniform, shows that the youngest stars in the Kepler field are 3–5 times rarer than stars 3 Gyr old. This trend holds for both known planet hosts and for the parent stellar sample. We attribute this “demographic cliff” to a combination of kinematic heating and a declining star formation rate in the Galaxy’s thin disk, and highlight its impact on the age distribution of known transiting exoplanets.

Predicting the evolution of texture and grain size during deformation and recrystallization of polycrystals using field fluctuations viscoplastic self-consistent crystal plasticity

This paper advances a recent formulation of a field fluctuations viscoplastic self-consistent (FF-VPSC) crystal plasticity model to predict not only the evolution of texture in polycrystalline metals undergoing deformation and recrystallization but also the evolution of grain size. The model considers stress and lattice rotation rate fluctuations inside grains to calculate intragranular misorientation spreads. The spreads are used for modeling of grain fragmentation during deformation and grain nucleation during recrystallization enabling the predictions of concomitant evolution of texture and grain size distributions. The evolutions of textures and grain size distributions are first simulated for commercially pure Cu undergoing severe plastic deformation (SPD) in high pressure torsion to agree well with corresponding experimental data. Next, the evolution of texture and grain size in an aluminum alloy (AA) 5182-O after simple tension and static recrystallization are predicted and compared with experiments. Finally, the predictions of texture and grain size distributions in a magnesium alloy WE43 undergoing a thermo-mechanical loading in the dynamic recrystallization regime are presented and compared with experiments. After validation, the model is coupled with the implicit finite element method (FEM) via a user-material subroutine (UMAT) in Abaqus to facilitate modeling of complex boundary conditions and geometries. The multilevel approach is referred to as FE-FF-VPSC in which every integration point embeds the FF-VPSC constitutive law, considering texture evolution and the directionality of deformation mechanisms operating at the single crystal level. FE-FF-VPSC is applied to simulate a sequence of rolling, recrystallization, and deep drawing of a circular cup of AA6022-T4. The simulated processing sequence demonstrates the versatility of the simulation framework developed in the present paper in not only predicting texture and grain size evolution and phenomena pertaining to behavior of materials but also geometrical shape changes important for the optimization of metal forming processes. To this end, the effects of initial texture and underlying anisotropy on the formation of earing profiles during deep drawing are simulated and discussed.

The turbulent cascade of inertia-gravity waves in rotating shallow water

In this work we study features of inertia-gravity wave turbulence in the rotating shallow water equations. On examining the dynamics of waves with varying rotation rates, we find that the turbulent cascade of waves is strongest at low rotation rates, forming a $k^{-2}$ energy spectrum, and a rich distribution of shocks in physical space. At high rotation rates, the forward cascade of waves weakens along with a steeper energy spectra and vanishing of shocks in physical space. The wave cascade is seen to be scale-local, resulting in a noticeable time interval for energy to get transferred from domain scale to dissipative scale. Furthermore, we find that the vortical flow has a non-negligible effect on the wave cascade, especially at high rotation rates. The vortical flow assists in the forward cascade of waves and shock formation at high rotation rates, while the waves by themselves in the absence of the vortical flow lack a forward cascade and shock formation at such high rotation rates. On investigating the physical space structures in the vortical flow and their connections to the wave cascade, we find that strain-dominant regions, that are located around the boundaries of coherent vortices, are the physical space regions that contribute majorly to the forward cascade of waves. Our results in general highlight intriguing features of dispersive inertia-gravity wave turbulence that are qualitatively similar to those seen in three-dimensional homogeneous isotropic turbulence and are beyond the predictions of asymptotic resonant wave interaction theory.

Leaning Sideways: VHS 1256−1257 b is a Super-Jupiter with a Uranus-like Obliquity

We constrain the angular momentum architecture of VHS J125601.92-125723.9, a 140 ± 20 Myr old hierarchical triple system composed of a low-mass binary and a widely separated planetary-mass companion, VHS 1256 b. VHS 1256 b has been a prime target for multiple characterization efforts, revealing the highest measured substellar photometric variability to date and the presence of silicate clouds and disequilibrium chemistry. Here we add a key piece to the characterization of this super-Jupiter on a Tatooine-like orbit: we measure its spin-axis tilt relative to its orbit, i.e., the obliquity of VHS 1256 b. We accomplish this by combining three measurements. We find a projected rotation rate vsinip=8.7±0.1kms−1 for VHS 1256 b using near-infrared high-resolution spectra from Gemini/IGRINS. Combining this with a published photometric rotation period indicates that the companion is viewed edge on, with a line-of-sight spin axis inclination of i p = 90° ± 18°. We refit available astrometry measurements to confirm an orbital inclination of io=23−13+10 degrees. Taken together, VHS 1256 b has a large planetary obliquity of ψ = 90° ± 25°. In total, we have three measured angular momentum vectors for the system: the binary orbit normal, companion orbit normal, and companion spin axis. All three are misaligned with respect to each other. Although VHS 1256 b is tilted like Uranus, their origins are distinct. We rule out planet-like scenarios including collisions and spin–orbit resonances, and suggest that top-down formation via core/filament fragmentation is promising.

Impact of spanwise rotation on flow separation and recovery behind a bulge in channel flows

Direct numerical simulations of spanwise-rotating turbulent channel flow with a parabolic bump on the bottom wall are employed to investigate the effects of rotation on flow separation. Four rotation rates, $Ro_b := 2\varOmega H/U_b = \pm 0.42$ , $\pm$ 1.0, are compared with the non-rotating scenario. The mild adverse pressure gradient induced by the lee side of the bump allows for a variable pressure-induced separation. The separation region is reduced (increased) when the bump is on the anti-cyclonic (cyclonic) side of the channel, compared with the non-rotating separation. The total drag is reduced in all rotating cases. Through several mechanisms, rotation alters the onset of separation, reattachment and wake recovery. The mean momentum deficit is found to be the key. A physical interpretation of the ratio between the system rotation and mean shear vorticity, $S:=\varOmega /\varOmega _s$ , provides the mechanisms regarding stability thresholds $S=-0.5$ and $-$ 1. The rotation effects are explained accordingly, with reference to the dynamics of several flow structures. For anti-cyclonic separation, particularly, the interaction between the Taylor–Görtler vortices and hairpin vortices of wall-bounded turbulence is proven to be responsible for the breakdown of the separating shear layer. A generalized argument is made regarding the essential role of near-wall deceleration and resultant ejection of enhanced hairpin vortices in destabilizing an anti-cyclonic flow. This mechanism is anticipated to have broad impacts on other applications in analogy to rotating shear flows, such as thermal convection and boundary layers over concave walls.

A novel gyroscope based on the slow surface acoustic wave in a phononic metamaterial

Limited to the direct modulation on the surface acoustic wave (SAW) by the rotation, the conventional SAW gyroscopes incur weak Coriolis effects and gyroscopic effects. In this paper, we innovatively utilize a phononic metamaterial (PM) operated at whispering-gallery modes (WGMs) as the vehicle for the Coriolis effect rather than SAW itself. The gyroscopic effects of this PM are investigated, and a new SAW gyroscope is subsequently proposed based on the slow SAW in PM. We show, combining theoretical modeling and finite element method simulation, that the rate of rotation can linearly induce the splitting of WGMs and modulate the phase velocity of SAW down to 4600 m/s (initial phase velocity of 5355 m/s); the direction of rotation results in the chiral symmetry of the PM vibration and the asymmetric distribution of the transmissive SAW. Besides, the proposed SAW gyroscope measures the angular velocity by detecting the phase shift resulting from rotation-dependent slow SAW in PM, obtaining a sensitivity of 0.016 deg/Hz when 50-cell PM. Compared with the existing SAW gyroscopes based on phase velocity modulation, the gyroscopic gain factor in this paper is enhanced by 430–1600 times. This work jumps out of the framework of directly modulating SAW in gyroscopes and provides an innovative scheme of the indirect modulations from the rotation-dependent PM on SAW, showing excellent performance and potential for angular velocity measurement in extreme environments.

Vibration characteristics of rolling bearing cage under speed variation conditions

Speed variation conditions will deteriorate the stress state of the rolling bearing internal components and aggravate the vibration of the cage, thereby affecting the service life and reliability of rolling bearings. In this paper, a nonlinear dynamic analysis model of the cylindrical roller bearing is established considering the rubbing effect and hydrodynamic contact between the cage and the guiding ring, as well as the sliding between the cage and other rolling elements. The vibration characteristics of the cage is discussed under the start-stop conditions and different fluctuations of rotation rate. The results show that the vibration of the cage mainly occurs at the middle and late stages of the acceleration process, and the impact mainly occurs at the middle stage of the deceleration process under the start-stop conditions. Moreover, the fluctuation of inner ring speed will enhance the unstable motion of the cage, among which the vibration and impact of the cage are most severe under the rectangular fluctuation of speed, followed by simple harmonic and triangular fluctuations. The findings can provide a theoretical guidance for improving the performance of rolling bearings and ensuring their safe and reliable operation.

Turbulent convection in rotating slender cells

Turbulent convection in the interiors of the Sun and the Earth occurs at high Rayleigh numbers $Ra$ , low Prandtl numbers $Pr$ , and different levels of rotation rates. To understand the combined effects better, we study rotating turbulent convection for $Pr = 0.021$ (for which some laboratory data corresponding to liquid metals are available), and varying Rossby numbers $Ro$ , using direct numerical simulations in a slender cylinder of aspect ratio 0.1; this confinement allows us to attain high enough Rayleigh numbers. We are motivated by the earlier finding in the absence of rotation that heat transport at high enough $Ra$ is similar between confined and extended domains. We make comparisons with higher aspect ratio data where possible. We study the effects of rotation on the global transport of heat and momentum as well as flow structures (a) for increasing rotation at a few fixed values of $Ra$ , and (b) for increasing $Ra$ (up to $10^{10}$ ) at the fixed, low Ekman number $1.45 \times 10^{-6}$ . We compare the results with those from unity $Pr$ simulations for the same range of $Ra$ and $Ro$ , and with the non-rotating case over the same range of $Ra$ and low $Pr$ . We find that the effects of rotation diminish with increasing $Ra$ . These results and comparison studies suggest that for high enough $Ra$ , rotation alters convective flows in a similar manner for small and large aspect ratios, so useful insights on the effects of high thermal forcing on convection can be obtained by considering slender domains.

The rotation rate of single- and double-lined southern O stars. Determining what increases the rotation rate in binaries

We determined the projected rotational velocity ($v i$) of 238 southern O stars selected from the Galactic O-star Survey. The sample contains 130 spectroscopic single stars (C) single-lined binaries (SB1), and SB2 systems (including eight triples). We applied the Fourier method to high-resolution spectra taken at Cerro Murphy, Chile, and supplemented by archival spectra. The overall $v i$ statistics peaks at slow rotators (40-100\,km/s) with a tail towards medium (100-200\,km/s) and fast rotators (200-400\,km/s). Binaries, on average, show increased rotation, which differs for close orb &lt; 10$\,d) and wide binaries (10\,d $&lt; orb &lt;$ 3700\,d), and for primaries and secondaries. The spin-up of close binaries is well explained by the superposition of spin-orbit synchronisation and mass transfer via Roche-lobe overflow. The increased rotation of wide binaries, however, needs another explanation. Therefore, we discuss various spin-up mechanisms. Timescale arguments lead us to favour a scenario where wide O binaries are spun-up by a combination of cloud or disk fragmentation, which lays the basis of triple and multiple stars, and the subsequent merging or swallowing of low-mass by higher-mass stars or proto-stars.

Further experimental analysis of undershot water wheels towards the development of a prototype model

ABSTRACT The current research aims to analyse the effect of the number and shape of the blades and the curvature of the flume bottom on the performance curves of undershot water wheels, based on experimental tests conducted in a fully instrumented laboratory facility. Six wheels are tested: four wheels with plane blades (16, 24, 36, 48) and two with 24 curved blades for two flume bottom configurations. Torque, mechanical power and mechanical efficiency performance curves are determined for several rotational speed and flow rate values. Results demonstrate that the maximum efficiency is achieved for the 36-plane blade wheel, the curved flume bottom reduces water losses under the wheel and increases efficiency, and the blades’ shape strongly influences the wheel efficiency. Non-dimensional performance curves are provided to generalise the results. This research provides relevant contributions towards the development of a low-cost energy recovery solution to be applied in water infrastructures.

Composition and polymerisation products influence on the viscosity of coal tar wash oil

Wash oil is a fraction obtained by the distillation of coal tar and is primarily used for the absorption of light oil from coke oven gas. During operation, the oil undergoes polymerization and loses some components, necessitating the removal of the used oil and its replacement with fresh wash oil. The rheological properties of the studied oils were determined using a Brookfield DV2T rotational controlled-shear rate rheometer. Gas chromatographic analysis, gas chromatography/mass spectrometry, and IR spectroscopy were employed to evaluate the oil’s characteristics. By adding individual components to the wash oil, it was found that these components could be categorized into three groups: viscosity enhancers, viscosity reducers, and non-polar oil substances with medium molecular weight that have no significant effect on viscosity. The addition of relatively polar components with greater molecular weight and a planar, rigid structure leads to an increase in viscosity. Conversely, the incorporation of naphthalene and its methyl homologues, which have lower molecular weights, reduces viscosity by disrupting intermolecular interactions; their lower heats of crystallization also inhibit the formation of structured order in the liquid, further contributing to the reduction in viscosity. The most substantial increase in oil viscosity was observed with the addition of indene-coumarone resins, attributed to their high molecular weight and polymer structure.

Numerical investigation on the end effects of the flow past a finite rotating circular cylinder with two free ends

This paper studies the impact of the aspect ratio and free end shape on the end effects in the flow past a rotating circular cylinder with two flat, radiused, hemispherical, and conical ends, using the large eddy simulation method at a Reynolds number of 4.6×104. The aspect ratio in the range of 6–30 and the rotation rate in the range of 0–3, are investigated. The results show that the mean drag coefficient initially decreases slightly before rapidly increasing with the rotation rate, with a critical rotation rate that rises from 1 to 1.5 as the aspect ratio increases from 6 to 30. In contrast, the mean lift coefficient increases with both the rotation rate and the aspect ratio. When the rotation rate increases and the aspect ratio decreases, the differences between the aerodynamic coefficients of the four end shapes become more pronounced. The flat end results in the highest mean drag and lift coefficients, while the hemispherical end yields the lowest ones. In addition, when the rotation rate increases, the alternate shedding vortices shift to the opposite side. They even disappear and increase the elongated streamwise vortices. Due to the combined impacts of the rotation and end effects, large-scale tip vortices are formed, significantly altering the wake structure. The intense rotation effect results in expanding the strong influence region of the end effects and shrinking (or even removing) the weak influence region.