Angle Of Attack Research Articles

Novel Eyelid Supraorbital Pretemporal Approach to the Anterior Communicating Artery Complex: A Quantitative Cadaveric Comparative Study

Abstract Objectives Access to the anterior communicating artery (ACom) complex may be achieved via the modified orbito-zygomatic (mOZ) or eyelid supraorbital (ES) approaches. Further, the ES approach may improve cosmesis at the cost of decreased exposure and maneuverability. Thus, a novel eyelid supraorbital pretemporal (ESP) approach, a combination of the ES approach with a pretemporal dissection, may optimize the shortcomings of the ES approach. Design This is a cadaveric study. Setting Five ES, ESP, and mOZ approaches were performed on cadaveric heads and compared. Participants Cadaveric specimens were provided under the University of Oklahoma Health Science Center's Willed Body Program. Main Outcome Measures Quantitative measures of exposure, maneuverability, and angles of attack in horizontal and vertical planes were compared between approaches. Results The ESP approach was superior in terms of exposure and deep maneuverability when compared with the ES approach (p < 0.01). In addition, this approach demonstrated superior angles of attack in vertical (p < 0.01) and horizontal (p = 0.045) planes. When compared with the mOZ approach, the ESP approach provided significantly greater exposure to the contralateral A2 (p < 0.01) with a less favorable horizontal angle of attack (p < 0.01). The ESP provides exact exposure to complete the pretemporal osteotomy, offering a unique perspective on the ACom complex. Conclusion When accessing the ACom complex, the ESP approach yields superior exposure and maneuverability compared with the ES approach and is comparable to the mOZ approach, with unique advantages provided by the addition of pretemporal osteotomy and dissection.

Effects of motion parameters on the propulsion characteristics of flexible pectoral fins in bio-manta robots

Manta rays have emerged as excellent bionic objects due to their efficient and flexible propulsion. A thorough understanding of the propulsion characteristics of manta ray robot pectoral fins is highly important for optimizing pectoral fin design and guidance strategies. Based on the silhouette and kinematics of the manta ray, we designed flexible pectoral fins and a 2DoF bionic mechanism that couples the flapping and pitching movements. Blade element theory was used to conduct a dynamic analysis of the bio-manta pectoral fins. The Strouhal number is used as a key dimensionless number that affects the hydrodynamic characteristics of a bio-manta robot during periodic flapping, as well as the flexibility of the pectoral fins and the angle of attack. We describe a series of hydrodynamic experiments conducted to analyze the single and interactive effects of the motion parameters of pectoral fin propulsion and regression analysis. The results show that when St is [0.2,0.4], the CT (thrust coefficient) of the flexible pectoral fin increases rapidly. When St increased beyond 0.4, the growth trend slows and remains essentially unchanged after 0.8. The CT reaches its peak, the propulsion efficiency is highest when St is between [0.4,0.6]. The angle of attack and the CT show a negative inverse quadratic trend, reaching a peak at 6.5°, and their influence is weaker than that of the frequency. The flexibility and CT showed a cubic trend, and the influence of flexibility was more significant when swimming at medium and low speeds. When swimming slowly, flexibility has a significant interactive effect on the frequency and angle of attack. However, these interactive effects reduce at high speeds. When the bio-manta robot starts at 0 speed, it should maneuver at high frequency and large amplitude while ensuring sufficient structural strength. After reaching a certain speed, the device maintains a large amplitude and low-frequency flapping operation to continuously drive propulsion.

Experimental analysis of propeller thrust in an undergraduate physics laboratory

As propulsive systems are challenging for undergraduates to understand, it is essential to design experiments that can help their visualization and testing. The development of digital technology (high-speed cameras, digital tracking software, or 3D printers) facilitates the implementation of such designs. We proposed to study the thrust produced by a propeller, whose operating principles are based on the conservation of linear momentum. The study was carried out on an air track to avoid frictional forces. Several system characteristics were established, such as the propellor’s rotation speed and angle of attack and different magnitudes were determined, including the dynamic thrust and static force values. 3D CAD software was used to design the propellers for the experiments, and 3D printers to produce them.

Hypersonic turbulent boundary layer over the windward side of a lifting body

In the present study, we performed direct numerical simulations for a hypersonic turbulent boundary layer over the windward side of a lifting body, the HyTRV model, at Mach number $6$ and attack angle 2 $^{\circ }$ to investigate the global and local turbulent features, and evaluate its difference from canonical turbulent boundary layers. By scrutinizing the instantaneous and averaged flow fields, we found that the transverse curvature on the windward side of the HyTRV model induces the transverse opposing pressure gradients that push the flow on both sides towards the windward symmetry plane, yielding significant effects of the azimuthal inhomogeneity and large-scale cross-stream circulations, moderate and azimuthal independent influences of adverse pressure gradient, and negligible impact of the mean flow three-dimensionality. Further inspecting the local turbulent statistics, we identified that the mean and fluctuating velocity become increasingly similar to the highly decelerated turbulent boundary layers over flat plates in that the mean velocity deficit is enhanced, and the outer layer Reynolds stresses are amplified as it approaches the windward symmetry plane, and prove to be self-similar under the scaling of Wei & Knopp (J. Fluid Mech., vol. 958, 2023, A9) for adverse-pressure-gradient turbulent boundary layers. Conditionally averaged Reynolds stresses based on strong sweeping and ejection events demonstrated that the Kelvin–Helmholtz instability of the strong embedded shear layer induced by the large-scale cross-stream circulations is responsible for the turbulence amplification in the outer layer. The strong Reynolds analogy that relates the mean velocity and temperature was refined to incorporate the non-canonical effects, showing considerable improvements in the accuracy of such a formula. On the other hand, the temperature fluctuations are still transported passively, as indicated by their resemblance to the velocity. The conclusions obtained in the present study provide potentially profitable information for turbulent modelling modification for the accurate predictions of skin friction and wall heat transfer.

Splitter-plate proximity-induced transitions in flow-induced vibration of a triangular prism

The effect of a splitter-plate downstream of an elastically mounted equilateral triangular prism on flow-induced vibration is numerically investigated at Reynolds number Re = 100, mass ratio m* = 10, damping ratio ζ = 0.005, cylinder-plate gap G* = 0.3, and various angle of attacks α = 0°–60°. The α = 0° and 60° correspond to vertex and edge of the cylinder facing the free stream. Under the effect of the splitter plate, a single transition from vortex-induced vibration (VIV) to proximity-induced galloping (PIG) in the vibrational response for an axisymmetric circular cylinder is reported, whereas, for the present non-axisymmetric triangular prisms, the varying α exhibits four proximity-induced transitions: VIV to modified VIV at smaller α = 0° and 25°, VIV to PIG at α = 35°, distinct VIV-galloping to combined PIG-galloping at α = 40°, and asymmetric to symmetric-galloping at larger α = 60°. The plate results in more symmetric vibration for high α ≥ 35°, while a reduction is observed for α ≤ 25°. The gap-flow leads to onset (α = 35°) and enhancement (α = 40°) of afterbody re-attachment on the prism, which significantly enhances the galloping instability and vibrational amplitude. A reduction in galloping instability leading to a slight reduction in amplitude is found for α = 60° prism. The study shows that the presence of the splitter-plate downstream influences near-wake structure and far-wake vortex shedding modes, which lead to stabilizing and destabilizing near-wake flow and distinct vibrational characteristics—depending on the angle of attack (α).

VAST as a generic, modular aeromechanics code for wind turbine simulation

In order to leverage the full potential wind energy, more research is needed both in the field and numerically. At DLR, the need for simulation competencies is expected to be met by the in-house developed generic and highly flexible multi-physics code VAST. While initially aimed at low- to medium-fidelity simulations of helicopter aeromechanics, the code is applicable to other problems like wind turbine computations. The goal of this paper is to present the general concept of VAST and briefly introduce the available physics models. Next to examples of successful application to helicopter simulation problems, first results in the field of wind energy are shown. The well-known IEA 15 MW reference wind turbine is used as a basis to compare VAST — both with a BEMT and a vortex theory inflow model — to other tools with similar and higher-fidelity physics modeling. For the rigid turbine, blade loads are compared with results of other tools using engineering models as well as CFD, showing good overall agreement. A more detailed evaluation of aerodynamic quantities like the angle of attack and the induced velocity field is presented for VAST and the CFD results. An outlook on the ongoing VAST developments is given.

Improved performance of k − ω SST turbulence model in predicting airfoil characteristics for a wide range of airfoil thicknesses

A variety of airfoils designed for wind turbine rotor blade applications were simulated with k − ω shear stress transport (SST) turbulence model in its standard form, the k − ω SST turbulence model with a modified a 1 constant (referred to as the a 1 method), the Spalart-Allmaras turbulence model, and the panel method XFoil. To assess their performance, the results of airfoil lift, drag, and coefficient of pressure were compared against available wind tunnel data, where available. The standard k −ω SST turbulence model is found to over-predict Reynolds shear stresses, delay the flow separation, and under-predict the separated-flow region on the airfoil’s suction side. Airfoil thicknesses between 11% and 36% of the chord length were studied. Using a modified a 1 constant, some airfoils exhibited up to a 20% improvement in the prediction of lift and drag coefficients within the post-stall range of angle of attack (AoA). It is important to note that the a 1 method’s applicability and effectiveness is specifically tested for airfoils, and its performance is highly dependent on the airfoil geometry.

АЭРОДИНАМИКА МОДЕЛИ ЖЕЛЕЗНОДОРОЖНОГО ГРУЗОВОГО ВАГОНА ПРИ РАЗНЫХ УГЛАХ АТАКИ ВОЗДУШНОГО ПОТОКА

The problem solution is considered for an airstream flow around a rectangular parallelepiped railway car model. The results of computer modeling in ANSYS CFX software system of air flow aerodynamics at its deviation from the longitudinal axis of the car are given. The k-ε turbulence model is used to close the Navier–Stokes equations averaged by Reynolds. The distribution diagrams of the flow velocities and pressures on the frontal and side surfaces of the vehicle are obtained. The values of aerodynamic drag coefficients of the car depending on the attack angle are determined. It is shown that when the attack angle increases from 0 to 10°, the aerodynamic coefficient changes nonlinearly, and this increase corresponds to the experimental values. The developed numerical modeling technique makes it possible to analyze the airflow around both railways rolling stock and automobiles.

A parametric optimization framework for fin-and-tube heat exchangers based on response surface methodology and artificial intelligence

This study presents a numerical investigation and provides a novel framework for the rapid parametric optimization of attack angles (α) and aspect ratios (e) in plate fin-and-tube heat exchangers (PFTHEs) featuring elliptical tubes. The methodology incorporates three-dimensional numerical simulations, response surface methodology (RSM), backpropagation neural network (BPNN), and Entropy-VIKOR. The study focuses on a PFTHE with a single elliptical tube, varying the attack angles (α) from −30° to 0° in 5° increments and the aspect ratios (e) from 0.4 to 1.0 in a step of 0.1. Air velocities (u) range from 0.4 to 3.2 m/s with an interval of 0.2 m/s, corresponding Reynolds number from 200 to 2200. The results indicate that using elliptical tubes reduces Δp and enhances heat transfer capacity, with the most significant improvements at an e of 0.4. Exponential relationships between dimensionless parameters Nu or f and Re are established for different range of α at specific e values. The synergistic effect of e, α, and Re or u on PFTHE performance is confirmed through RSM and BPNN analysis. Their R2 values are no less than 0.896 and reach a maximum of 0.998, indicating excellent predictive accuracy. Utilizing Entropy-VIKOR method, the framework identifies a suitable design solution with e = 0.6, α = -20°, and u = 3.2 m/s. This solution exhibits a 5 % increase in h and a 58 % reduction in Δp relative to the corresponding circular tube. The study provides specific expressions relating design variables to thermal–hydraulic behavior and indicates carefully selecting the α and e can improve the overall performance. In summary, these findings have significant implications for reducing optimization design period for PFTHEs with small tube diameters.

Flow sensing on dragonfly wings.

One feature of animal wings is their embedded mechanosensory system that can support flight control. Insect wings are particularly interesting as they are highly deformable yet the actuation is limited to the wing base. It is established that strain sensors on insect wings can directly mediate reflexive control; however, little is known about airflow sensing by insect wings. What information can flow sensors capture and how can flow sensing benefit flight control? Here, we use the dragonfly (Sympetrum striolatum) as a model to explore the function of wing sensory bristles in the context of flight control. Combining our detailed anatomical reconstructions of both the sensor microstructures and wing architecture, we used computational fluid dynamics simulations to ask the following questions. (1) Are there strategic locations on wings that sample flow for estimating aerodynamically relevant parameters such as the local effective angle of attack? (2) Is the sensory bristle distribution on dragonfly wings optimal for flow sensing? (3) What is the aerodynamic effect of microstructures found near the sensory bristles on dragonfly wings? We discuss the benefits of flow sensing for flexible wings and how the evolved sensor placement affects information encoding.

Tuning the Actuator Line Method to Properly Modelling Tip Effects in Finite-Length Blades

The Actuator Line Method (ALM) is gaining popularity in wind turbine simulations, as it can better handle some of the challenging operating conditions experienced by modern machines, such as highly turbulent inflows, severe aero-elastic forcing, and complex rotor-to-rotor interactions. However, it still falls behind other medium-fidelity methods such as the Lifting Line Free Vortex Wake (LLFVW) when it comes to resolving tip vortices and their effect on the blade spanwise load profile. The reason for such behavior is still unclear. A recent study suggested that this issue can be solved by reducing the scale of the angle of attack (α) sampling and force insertion towards the tip, without the need of additional corrections. This study builds on these findings to further investigate how the ALM base formulation - in terms of α sampling and force insertion - can be tuned to properly describe tip effects. An in-house ALM tool was employed to simulate a finite, constant-chord, NACA0018 wing, for which high-fidelity blade-resolved CFD (BR-CFD) data are available as benchmark. In the first part of the work, different strategies are outlined, including a novel approach for the de-coupling of the angle of attack sampling step from the force projection one, here called DE-coupled LineAverage (DELA). Their accuracy and sensitivity to ALM numerical settings are assessed at a fixed wing pitch angle of 6°. The analysis is then extended to a wider range of blade pitch angles, benchmarking the new ALM formulation against BR-CFD, ALM with the Dağ and Sørensen correction, and LLFVW in terms of blade loads, tip vortex structure, and computational effort.

Effect of branch-like structures created by vortex generators on cavitation dynamics at high angle of attack

When hydraulic machines operate away from their design condition, the angle between the inflow and the blade's leading edge increases significantly, causing severe cavitation. To address this, this investigation focuses on cavitation flow around hydrofoil with a high incidence angle. The effects of the vortex generators (VGs) on cavitation evolution, pressure fluctuations, and flow-induced noise were discussed. Experiments and simulations were jointly employed in this work. The results indicate that under current conditions, cavitation initiates upstream of the VGs, closer to the leading edge. The branch-like vortex cavitation induced by the VGs enhances the stability of the shedding cavities in the midstream of the hydrofoil, leading to a 15.24% reduction in the primary frequency of cavitation shedding. With the addition of the VGs, the amplitude of pressure fluctuations on the hydrofoil surface is reduced. Also, the acoustic power drops over the entire spectrum, especially in the high-frequency range. The sound pressure corresponding to the main frequency of cavitation noise is reduced by 7 dB.

Fluid–structure interaction of a marine rudder at incidence in the wake of a propeller

The structural response of a rudder in the wake of a marine propeller is investigated by one-way fluid–structure interaction approach. The unsteady pressure field gathered by detached eddy simulations is provided to a structural solver for the computation of deformations and stresses of the rudder. The study compares the structural response of the rudder at neutral and two equal and opposite rotations, which are representative of design conditions in straight motion and maneuvering conditions that are experienced under the action of the autopilot for course control or weak maneuvering. The analysis sheds light on the different structural behavior at the two opposite rotation angles, caused by asymmetrical variation along the span of the rudder of the angle of attack induced by the propeller slipstream, by considering the different role played by the tip and hub vortical systems. The test case consists of a rudder with a rectangular plane area and National Advisory Committee for Aeronautics 0015 sectional profile located past the E779A propeller. The propeller operates at low loading conditions, and the rudder is set at incidence δ=0∘,±4∘. The study shows that the response of the rudder is driven by flap and torsion and is asymmetric for the two and opposite rotations. The mean deformation and vibratory response are magnified for δ=−4∘ by at least 70% and 20% for the lateral and edgewise deflections, respectively, with respect to the opposite rudder incidence. In general, the excitation generated by the tip vortex is stronger than that of the hub vortex. In the most critical condition, at δ=−4∘, the excitation associated with the tip vortex is nearly double that of the hub vortex.

Experimental investigation on key parameters influencing unsteady aerodynamics of a 3:2 rectangular prism in accelerating flow

This study investigates the unsteady aerodynamic characteristics of a 3:2 rectangular prism under accelerating flow. Wind tunnel tests were primarily conducted in the steady flow to establish a baseline for assessing the unsteady effects induced by flow acceleration on the aerodynamic forces. Aerodynamic parameters in the time and frequency domains were compared across different accelerating flow cases to analyze the influence of accelerating flow characteristics on the unsteadiness of aerodynamic forces. The results demonstrate that the lift force exhibits more pronounced unsteady characteristics compared to drag and moment. The unsteady behavior is primarily influenced by the wind attack angle, starting wind velocity, and maximum acceleration. For wind attack angles of 0° or 90°, the accelerating flow primarily reduces the amplitude of lift fluctuations. In contrast, for other wind attack angles, the accelerating flow causes a deviation in the time-varying mean of lift from the quasi-steady value, accompanied by an amplification of lift fluctuations. Furthermore, the increase in the starting wind velocity leads to a decrease in the deviation of aerodynamic lifts, indicating that higher starting wind velocities weaken the unsteady aerodynamic characteristics induced by accelerating flow. On the other hand, the increase in flow acceleration enhances the unsteady effect on aerodynamic lift, especially for accelerating flow with higher starting wind velocities. Moreover, the Strouhal number during the accelerating process is lower than that in the steady flow, and the degree of reduction is also influenced by starting wind velocity and maximum acceleration.

Аппроксимация экспериментальных коэффициентов гидродинамических сил крыльевого гидродинамического якоря

The article considers a full-scale comparative experiment conducted in 2020 in the water area of the Novosibirsk reservoir on the simultaneous drift of six marine life rafts with a capacity of 6 people each. Each raft was equipped with one of the developed hydrodynamic anchors (HDA); one raft had a standard parachute floating anchor; one raft had no means of preventing drift. The wing hydrodynamic armature showed good results in reducing the drift velocity. To develop design methods of this kind, hydrodynamic forces were determined in the direct experimental basin of the Siberian State University of Water Transport (SSUWT) by towing with different speeds and angles of attack. According to the tests conducted in the direct experimental pool of the police Department, HDA the coefficients of hydrodynamic forces were obtained. It is noted that the HDA is made in full size, which does not require recalculation according to similarity criteria; the values of the coefficients show an unstable dependence on the towing speed, which is explained by the influence of errors of the experimental method and required averaging of the results. To substantiate the possibility of using the averaging method, the results of numerical modeling of the work of HDA carried out in the Ansys Fluent program are used, which revealed a very weak dependence of the coefficients on the flow rate. On this basis, a decision was made on the possibility of averaging coefficients related to flow velocities v ≥ 0.2 m/s, at which the spread of coefficient values is relatively small. The averaged values of the coefficients obtained in the physical experiment are approximated in their ranges of angles of attack by quadratic polynomials to smooth out the results and facilitate their use in mathematical models of the device operation.

Improved performance evaluation of a dual passage solar thermal collector using staggered turbulators

Energy exists in various forms and plays a crucial role in global economic development and modernization. Solar energy is a prominent choice among several alternatives as an energy source to meet the demand. To harness solar energy for heating applications, the most basic approach is to transform it into thermal energy through the use of solar thermal collectors (STC). The thermal effectiveness of the dual passage solar thermal collector (DP-STC) is particularly poor. An effective approach to enhancing its thermohydraulic performance (ηTHPP) involves employing turbulators on the absorber plate (AP). This study investigates the impact on ηTHPP of DP-STC providedwith single V-shaped staggered baffles (SVSSBs). The impact of various geometrical elements, such as relative staggered baffle position (PB′/PB) ranging from 0.45 to 0.75, relative staggered baffle size (B/HB) from 2.5 to 4.0, and relative roughness pitch (PB/HB) from 1.0 to 2.5, are investigated for Reynolds numbers (ReX) ranging from 3000 to 19000. The remaining geometrical parameters, including the relative roughness height (HB/HC) = 0.40, relative gap position (Gd/Lv) = 0.67, relative gap size g/HB = 1, and angle of attack (αB) = 60°, remained fixed. Notable among the findings of this research is the fact that, SVSSBs performed best in comparison to other turbulators reported in the literature review. The ηTHPP reached its maximum value of 3.67 for the case with SVSSBs with PB/HB = 1.5, PB′/PB = 0.65, andB/HB = 3.5 atReX = 17000. The correlations are also developed for the Nusselt number (NuBP) and friction factor (fBP), using experimental data.

A three-dimensional spring-loaded inverted pendulum walking model considering human movement speed and frequency

The spring-loaded inverted pendulum (SLIP) model is an effective model to capture the essential dynamics during human walking and/or running. However, most of the existing three-dimensional (3D) SLIP model does not explicitly account for human movement speed and frequency. To address this knowledge gap, this paper develops a new SLIP model, which includes a roller foot, massless spring, and concentrated mass. The governing equations-of-motion for the SLIP model during its double support phase are derived. It is noted that in the current formulation, the motion of the roller foot is prescribed; therefore, only the equations for the concentrated mass need to be solved. To yield model parameters leading to a periodic walking gait, a constrained optimization problem is formulated and solved using a gradient-based approach with a global search strategy. The optimization results show that when the attack angle ranges from 68° to 74°, the 3D SLIP model can yield a periodic walking gait with walking speeds varying from 0.5 to 2.0 m s−1. The predicted human walking data are also compared with published experimental data, showing reasonable accuracy.

Turbulence model study for aerodynamic analysis of the leading edge tubercle wing for low Reynolds number flows

A turbulence model study was performed to analyze the flow around the Tubercle Leading Edge (TLE) wing. Five turbulence models were selected to evaluate aerodynamic force coefficients and flow mechanism by comparing with existing literature results. The selected models are realizable k-ε, k-ω Shear Stress Transport (SST), (γ−Reθ) SST model, Transition k-kl-ω model and Stress- ω Reynolds Stress Model (RSM). For that purpose, the TLE wing model was developed by using the NACA0021 airfoil profile. The wing model is designed with tubercle wavelength of 0.11c and amplitude of 0.03c. Numerical simulation was performed at chord-based Reynolds number of Rec = 120,000. The Computational Fluid Dynamic (CFD) simulation reveals that among the selected turbulence models, Stress- ω RSM estimated aerodynamic forces (i.e. lift and drag) coefficients closest to that of the experimental values followed by realizable k-ε, (γ−Reθ) SST model, k-ω SST model and k-kl-ω model. However, at a higher angle of attacks i.e. at 16° & 20° k-ω SST model predicted closest drag and lift coefficient to that of the experimental values. Additionally, the critical observation of pressure contour confirmed that at the lower angle of attack Stress- ω RSM predicted strong Leading Edge (LE) suction followed by realizable k-ε, (γ−Reθ)SST model, k-ω SST model and k-kl-ω model. Thus, the superiority of Stress- ω RSM in predicting the aerodynamic force coefficients is shown by the flow behavior. In addition to this pressure contours also confirmed that k-kl-ω model failed to predict tubercled wing aerodynamic performance. At higher angles of attacks k-ω SST model estimated aerodynamic force coefficients closest to that of the experimental values, thus k-ω SST model is used at 16° & 20° AoAs. The observed streamline behavior for different turbulence models showed that the Stress- ω RSM model and k-kl-ω model failed to model flow behavior at higher AoAs, whereas k-ω SST model is a better approach to model separated flows that experience strong flow recirculation zone.

Enhancing Savonius Rotor Performance With Zigzag Surface Investigated at Drag Force, Pressure, and Flow Visualization Analysis

Savonius, a type of vertical-axis wind turbine, is a small-scale energy conversion device suitable for low wind speeds, such as those characteristic of Indonesian wind speeds, yet has low efficiency. Savonius is a drag-type turbine. Drag force on the surface is affected by roughness or wavyness. The purpose of this study is to analyze the impact of applying wavy (zigzag) variations to the concave surface of Savonius blades on their performance. This was achieved by the use of 3D computational fluid dynamics simulation at TSR 0.6 with a velocity inlet of 5 m/s. The model was semicircular, zigzag on the concave surface on semicircular with t = 0.75, t = 0.25, and t = 1 mm. The result of this study's CD maximum is 1,817 at the zigzag model with t = 1 and CD avrg =1.24. The average drag coefficient increased by 14 percent compared to the conventional semicircular rotor. The maximum Cp value is also found at t = 1 mm, which is 0.315. The power coefficient increased by 29 percent compared to the conventional semicircular rotor. The total pressure on the blade shows the highest model with t = 1 mm at the same angle of attack (α = 30). Zigzag on the concave surface affects blade pressure, which improves the performance of the Savonius rotor.

Miniaturized high signal-to-noise ratio optical air data system using a compact multi-axis parallel transceiver for airborne application

We have developed a miniaturized multi-channel parallel optical air data system with high signal-to-noise ratio for airborne application. In the system, we designed a fiber amplifier with multi-channel high-energy output that was respectively used as the transmitting signals and a compact multi-axis transceiver with an entrance pupil diameter of 70 mm that was used to receive multi-channel signals simultaneously. We demonstrated the performance of our system both on ground and on board. On ground, the measured line-of-sight speed had an average error of 0.02 m/s and a standard deviation of 0.15 m/s. On board, the standard deviation between the true air speed, angle of attack, and angle of sideslip measured by our system and a commercial Swiss air data system was 1 kt, 0.68°, and 0.54°, respectively, and those standard deviation between our system and a system with the same design but employing multiple single-axis telescopes with entrance pupil diameter of 30 mm was 0.34 kt, 0.36°, and 0.28°, respectively. The signal-to-noise ratio of our system was 4.5 times higher than that of the system with small single-axis telescopes. Our system is very promising for airborne applications because of its small volume, high signal-to-noise ratio, and high data rate.