Journal articles: 'Ducted Rotor'

1

He, Xing Zhu, Shu Nan Liu, Yan Li Chen, Chun Xue Wang, and Song Yang. "Research on Hover Characteristics of Ducted Fan with Coaxial Rotors." Applied Mechanics and Materials 427-429 (September 2013): 216–20. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.216.

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The method of handling respectively is used to refine the grid of ducted fan with coaxial rotors. Research the complex flow field of the ducted fan by numerical simulation to analyze its hover characteristics. The curve of the upper rotors lift, the lower rotors lift, the ducts lift with collective and the distance between rotors is got respectively. By comparing with the aerodynamic characteristics of ducted fan with a single rotor, results show that there is interference between the upper and lower rotors, the upper one interferes the lower one more heavily and interference is reduced with the increase of distance between the rotors; the duct of ducted fan with coaxial rotors can provide more lift than the one with a single rotor.

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2

Mishra*, Mr Vinay, and Dr H. K. Paliwal. "CFD Analysis of Torque and Power for Single Rotor, Dual Rotor, and Ducted Dual Rotor Wind Turbine." International Journal of Engineering and Advanced Technology 10, no. 4 (April 30, 2021): 215–17. http://dx.doi.org/10.35940/ijeat.d2500.0410421.

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With the present advancement, a wind turbine needs a wind rotor with high torque and power. The present study aims to enhance the torque and power of wind turbine by employing the ducted dual rotor. In this regard, CFD analysis is performed to analyze the torque and power produced for horizontal axis single rotor bare wind turbine, dual rotor wind turbine, and convergent-divergent ducted type dual rotor wind turbine. The comparative study is conducted to enhance the power and torque for the aforementioned rotor type. The results highlight the maximum value of torque for a dual ducted wind turbine is 36.9% more than a dual rotor at 16 m/s of wind velocity and 92.2 % more than a single rotor at 16 m/s of wind velocity, and the maximum value of the power produced for a dual ducted wind turbine is 40.48% more than a dual rotor at 16 m/s of wind velocity and 139.66% more than a single rotor at 16 m/s of wind velocity. Therefore result suggested that a dual ducted wind turbine is better than a single rotor wind turbine.

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3

Roh, Nahyeon, Sejong Oh, and Donghun Park. "Aerodynamic Characteristics of Helicopter with Ducted Fan Tail Rotor in Hover under Low-Speed Crosswind." International Journal of Aerospace Engineering 2020 (October 27, 2020): 1–14. http://dx.doi.org/10.1155/2020/7059209.

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The tail rotor of a helicopter operating under low-speed crosswind undergoes highly complex flow due to the interaction between the main rotor, fuselage, and tail rotor system. In this study, numerical simulations have been conducted on the complete configuration of a helicopter with a ducted fan tail rotor system (comprising a main rotor, ducted fan tail rotor, fuselage, and empennage) to analyze the wake interaction in hovering flight under various crosswind directions. The flow characteristics around the tail rotor, the tail rotor thrust, and the yawing moment of the helicopter are investigated and evaluated. The aerodynamic forces are compared with those of a helicopter with an open-type tail rotor. The results indicate that the aerodynamic performance of the ducted fan tail rotor is highly affected by the wakes of both the main rotor and port wing. Nevertheless, the helicopter with a ducted fan tail rotor is observed to be much more directionally stable under various crosswind directions, than that with an open-type tail rotor. This is because the rotor is protected by the fixed part of the tail rotor system in the former case.

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Oweis, Ghanem F., David Fry, Chris J. Chesnakas, Stuart D. Jessup, and Steven L. Ceccio. "Development of a Tip-Leakage Flow Part 2: Comparison Between the Ducted and Un-ducted Rotor." Journal of Fluids Engineering 128, no. 4 (March 2, 2006): 765–73. http://dx.doi.org/10.1115/1.2201619.

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The vortical flow in the tip region of a three-bladed rotor was examined using particle imaging velocimetry (PIV). The vortex forming at the tip of the un-ducted propeller was compared to the tip-leakage vortex of the ducted rotor. The planar flow fields were used to identify regions of concentrated vorticity and determine instantaneous vortex properties, revealing the presence of a primary tip-leakage vortex surrounded by a number of secondary vortices. Comparison between the ducted and un-ducted rotor indicated that the presence of the duct reduced the relative strength of the primary tip vortex, making its strength a smaller fraction of the overall shed circulation near the tip. The weaker tip-leakage vortex then became closer in strength to the other secondary vortices in the tip-flow region. However, for the rotor tip geometry considered here, the radius of the primary vortex core did not vary substantially between the ducted and un-ducted cases. The variability of the flow was larger for the ducted case, in terms of the primary vortex position, its identified circulation, core size, and inferred core pressure. This variability was also observed in the scaled velocity fluctuations near the core of the vortex.

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5

Kim, Woo-Yul, Santhosh Senguttuvan, and Sung-Min Kim. "Effect of Rotor Spacing and Duct Diffusion Angle on the Aerodynamic Performances of a Counter-Rotating Ducted Fan in Hover Mode." Processes 8, no. 11 (October 23, 2020): 1338. http://dx.doi.org/10.3390/pr8111338.

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The aerodynamic performance of a counter-rotating ducted fan in hover mode is numerically analyzed for different rotor spacings and duct diffusion angles. The design of the counter-rotating fan is inspired by a custom-designed single rotor ducted fan used in a previous study. The numerical model to predict the aerodynamic performance of the counter-rotating ducted fan is developed by adopting the frozen rotor approach for steady-state incompressible flow conditions. The relative angle between the front and the rear rotor is examined due to the usage of the frozen rotor model. The results show that the variation of thrust for the different relative angles is extremely low. The aerodynamic performances are evaluated by comparing the thrust, thrust coefficient, power coefficient, and figure of merit (FOM). The thrust, thrust coefficient, and FOM slightly increase with increasing rotor spacing up to 200 mm, regardless of the duct diffusion angle, and reduce on further increase in the rotor spacing. The duct diffusion angle of 0° generates about 9% higher thrust and increases the FOM by 6.7%, compared with the 6° duct diffusion angle. The duct diffusion angle is highly effective in improving the thrust and FOM of the counter-rotating ducted fan, rather than the rotor spacing.

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Misiorowski, Matthew P., Farhan S. Gandhi, and Assad A. Oberai. "Computational Analysis and Flow Physics of a Ducted Rotor in Edgewise Flight." Journal of the American Helicopter Society 64, no. 4 (October 1, 2019): 1–14. http://dx.doi.org/10.4050/jahs.64.042004.

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This study examines the performance of the ducted rotor in hover and edgewise flight conditions. The flow over a threedimensional model of a ducted rotor was simulated using the Spalart–Allmaras Reynolds-averaged Navier–Stokes model implemented in a stabilized finite element method. A sliding mesh was used to conveniently account for the large-scale motion associated with rotor revolutions. The simulation results were analyzed to understand the flow physics and quantify the contributions of the rotor and various sections of the duct interior surfaces on the total aerodynamic forces (thrust, drag, and side force) and moments (pitching and rolling). In edgewise flight, freestream flow separates off the front of the duct inlet, causing a region of recirculating flow and upwash in the rotor plane. The upwash region biases rotor thrust production to the front of the disk. The swirl velocity further biases the region of flow separation over the inlet and upwash at the front of the rotor toward the retreating side of the disk. The shift of thrust production on the rotor and duct toward the front produces a strong nose-up pitching moment on the ducted rotor. The rear of the diffuser is a significant contributor to the total drag; this force includes a nose-down pitch moment, which partially negates the moment from the duct inlet. The rotor is the primary source of vertical vibratory forces as well as vibratory pitching and rolling moments. The small tip clearance of the rotor causes a local interaction between the blade tip and duct that is the dominant contributor to in-plane vibratory forces on the ducted rotor.

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7

Kanya, Benjamin, and Kenneth D. Visser. "Experimental validation of a ducted wind turbine design strategy." Wind Energy Science 3, no. 2 (December 18, 2018): 919–28. http://dx.doi.org/10.5194/wes-3-919-2018.

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Abstract. A synergistic design strategy for ducted horizontal axis wind turbines (DWTs), utilizing the numerical solution of a ducted actuator disk system as the input condition for a modified blade element momentum method, is presented. Computational results of the ducted disk have shown that the incoming flow field for a DWT differs substantially from that of a conventional open rotor. The rotor plane velocity is increased in the ducted flow field, and, more importantly, the axial velocity component varies radially. An experimental full-scale 2.5 m rotor and duct were designed, using this numerical strategy, and tested at the University of Waterloo's wind turbine test facility. Experimental results indicated a very good correlation of the data with the numerical predictions, namely a doubling of the power output at a given velocity, suggesting that the numerical strategy can provide a means for a scalable design methodology.

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8

Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Maximal power per device area of a ducted turbine." Wind Energy Science 6, no. 4 (July 29, 2021): 1031–41. http://dx.doi.org/10.5194/wes-6-1031-2021.

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Abstract. The aerodynamic design of a ducted wind turbine for maximum total power coefficient was studied numerically using the axisymmetric Reynolds-averaged Navier–Stokes equations and an actuator disc model. The total power coefficient characterizes the rotor power per total device area rather than the rotor area. This is a useful metric to compare the performance of a ducted wind turbine with an open rotor and can be an important design objective in certain applications. The design variables included the duct length, the rotor thrust coefficient, the angle of attack of the duct cross section, the rotor gap, and the axial location of the rotor. The results indicated that there exists an upper limit for the total power coefficient of ducted wind turbines. Using an Eppler E423 airfoil as the duct cross section, an optimal total power coefficient of 0.70 was achieved at a duct length of about 15 % of the rotor diameter. The optimal thrust coefficient was approximately 0.9, independent of the duct length and in agreement with the axial momentum analysis. Similarly independent of duct length, the optimal normal rotor gap was found to be approximately the duct boundary layer thickness at the rotor. The optimal axial position of the rotor was near the rear of the duct but moved upstream with increasing duct length, while the optimal angle of attack of the duct cross section decreased.

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9

Jiang, Yuening, Hai Li, and Hongguang Jia. "Aerodynamics Optimization of a Ducted Coaxial Rotor in Forward Flight Using Orthogonal Test Design." Shock and Vibration 2018 (May 28, 2018): 1–9. http://dx.doi.org/10.1155/2018/2670439.

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To investigate the aerodynamic complexities involved in the combination of freestream and propeller’s suction flow field of ducted coaxial rotors system in forward flight, an orthogonal L16(43) test design has been applied to optimize the design parameters including forward speed, pitch angle, and axial spacing between rotors. Multiblock grids and Multiple Frame of Reference (MFR) method are adopted for calculating aerodynamic performance of the system, hover characteristic was compared with experimental data obtained from the test stand, and the thrust performance is well predicted for various rotor spacing and a range of rpm. This solution approach is developed for the analytical prediction of forward flight and the simulation results indicated that the design parameters influenced lift, drag, and torque reduced in the order: wind speed > rotor spacing > pitch angle, wind speed > pitch angle, and rotor spacing > wind speed > pitch angle, respectively. The optimal rotor spacing and pitch angle were determined to maximize the aerodynamic performance considering high lift, low drag, and trimmed torque.

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10

Zhong, Guo, Jun Huang, and Mingxu Yi. "Design parameters improvement of helicopter ducted tail rotor." Aircraft Engineering and Aerospace Technology 90, no. 2 (March 5, 2018): 237–45. http://dx.doi.org/10.1108/aeat-01-2017-0033.

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Purpose The purpose of this paper is to reduce the acoustic noise of helicopter ducted tail rotor. Design/methodology/approach To predict the noise accurately, a thin-body boundary element method (BEM)/Ffowcs Williams–Hawkings method is developed in this paper. It is a hybrid method combining the BEM with computational aeroacoustics and can be used efficiently to predict the propagation of sound wave in the duct. Findings Compared with the experimental results, the proposed method of acoustic noise is rather desirable. Practical implications Then several geometry parameters are modified to investigate the noise reduction of ducted tail rotor by using the numerical prediction method. Originality/value The aerodynamic and acoustic performance of different modification tasks is discussed. These results demonstrate the validity of design parameters modification of ducted tail rotor in acoustic noise reduction.

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11

Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Ducted wind turbine optimization and sensitivity to rotor position." Wind Energy Science 3, no. 1 (April 25, 2018): 221–29. http://dx.doi.org/10.5194/wes-3-221-2018.

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Abstract. The design of a ducted wind turbine modeled using an actuator disc was studied using Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations. The design variables included the rotor thrust coefficient, the angle of attack of the duct cross section, the radial gap between the rotor and the duct, and the axial location of the rotor in the duct. Two different power coefficients, the rotor power coefficient (based on the rotor swept area) and the total power coefficient (based on the exit area of the duct), were used as optimization objectives. The optimal value of thrust coefficients for all designs was nearly constant, having a value between 0.9 and 1. The rotor power coefficient was sensitive to rotor gap but was insensitive to the rotor's axial location for positions ranging from upstream of the throat to nearly half the distance down the duct. Compared to the design that maximized rotor power coefficient, the design for maximal total power coefficient was characterized by a smaller angle of attack, a smaller rotor gap, and a downstream placement of the rotor. The insensitivity of power output to the rotor position implies that a rotor placed further downstream in the duct could produce the same power with a considerably smaller duct exit area and thus a greater total power coefficient. The design for that maximized total power coefficient exceeded Betz's limit with a total power coefficient of 0.67.

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12

Ma, Yunpeng, Mingxu Yi, Lifeng Wang, and Jun Huang. "Computation of Aerodynamic Noise Radiated from Ducted Tail Rotor Using Boundary Element Method." Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/5726253.

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A detailed aerodynamic performance of a ducted tail rotor in hover has been numerically studied using CFD technique. The general governing equations of turbulent flow around ducted tail rotor are given and directly solved by using finite volume discretization and Runge-Kutta time integration. The calculations of the lift characteristics of the ducted tail rotor can be obtained. In order to predict the aerodynamic noise, a hybrid method combining computational aeroacoustic with boundary element method (BEM) has been proposed. The computational steps include the following: firstly, the unsteady flow around rotor is calculated using the CFD method to get the noise source information; secondly, the radiate sound pressure is calculated using the acoustic analogy Curle equation in the frequency domain; lastly, the scattering effect of the duct wall on the propagation of the sound wave is presented using an acoustic thin-body BEM. The aerodynamic results and the calculated sound pressure levels are compared with the known technique for validation. The sound pressure directivity and scattering effect are shown to demonstrate the validity and applicability of the method.

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13

Głowacki, Dominik, and Mirosław Rodzewicz. "The Elaboration of the Method of Fatigue Testing of the Rotor of the Mosups Plane Propulsion System." Fatigue of Aircraft Structures 2016, no. 8 (June 1, 2016): 97–103. http://dx.doi.org/10.1515/fas-2016-0008.

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AbstractThis paper concerns fatigue testing of the rotor of the propulsion system for the MOSUPS – an unmanned aircraft designed in a joint wing configuration, and equipped with a ducted propeller. The work presents the analysis of the stresses and deformations of the rotor structure as well as the form of the loading cycle. The aim of the paper is to introduce the concept of a simplified method of fatigue testing of multi-blade rotors. With the sophisticated geometry of the rotor in mind – the authors applied the FEM tools and implemented the ANSYS and nCode programs. The prototype of the fatigue stand built by the authors is also presented in the paper.

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14

Bontempo, R., and M. Manna. "Solution of the flow over a non-uniform heavily loaded ducted actuator disk." Journal of Fluid Mechanics 728 (July 5, 2013): 163–95. http://dx.doi.org/10.1017/jfm.2013.257.

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AbstractThe paper presents an extension to ducted rotors of the nonlinear actuator disk theory of Conway (J. Fluid Mech., vol. 365, 1998, pp. 235–267) and it is exact for incompressible, axisymmetric and inviscid flows. The solution for the velocities and the Stokes stream function results from the superposition of ring vortices properly arranged along the duct surface and the wake region. Using a general analytical procedure the flow fields are given as a combination of one-dimensional integrals of expressions involving complete as well as incomplete elliptic integrals. The solution being exact, the proper shape of the slipstream whether converging or diverging is naturally accounted for, even for heavy loads. A semi-analytical method has been developed that enables the flow induced by an actuator disk housed in a contoured duct to be solved duly accounting for the nonlinear mutual interaction between the duct and the rotor. Non-uniform load distributions, rotor wake rotation and ducts of general shapes and thickness distribution can be dealt with. Thanks to its reduced numerical cost, the method is well suited for the design and/or analysis of ducted rotors for marine, wind and aeronautical applications.

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Korgen, Ben J. "Visualizing the Meanings of Mathematical Expressions Used in Fluid Mechanics, Oceanography, and Ocean Engineering." Marine Technology Society Journal 37, no. 2 (June 1, 2003): 23–30. http://dx.doi.org/10.4031/002533203787537357.

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This paper calls attention to a tool and an approach that can facilitate understanding the mathematical expressions commonly used to describe fluid flows. The tool recommended is the ducted rotor current meter. This device can visually represent changes in flow speed through the use of moving parts that can be observed, photographed, or videotaped. Being ducted, this device also facilitates visualizing flows that have been divided into components moving along whatever coordinate axes have been chosen. For visualizing the meanings of the mathematical expressions used in fluid mechanics, oceanography, and ocean engineering, ducted rotors must be used in arrays, most often in pairs or groups of four. The approach recommended is less important for visualizing the meanings of the simplest mathematical expressions such as the partial derivatives that describe gradients of velocity shear. The same approach becomes more important for visualizing the meanings of the more complicated mathematical expressions such as those that describe rotational flow fields or nonlinear accelerations.

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16

ROŚKOWICZ, Marek, Ryszard CHACHURSKI, Sławomir TKACZUK, Piotr LESZCZYŃSKI, Maciej MAJCHER, and Łukasz OMEN. "Strength Analysis of a Ducted Axial Fan Blade." Problems of Mechatronics Armament Aviation Safety Engineering 9, no. 4 (December 30, 2018): 85–100. http://dx.doi.org/10.5604/01.3001.0012.7334.

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This paper presents a numerical strength analysis of a ducted axial fan blade. Ducted axial fans are a large group of fluid-flow machines. The analysis was designed to determine the causes of cyclic failures of a ventilation unit. The paper presents a reverse engineering approach to the mapping of the fan blade’s geometrical features. The geometrical features were mapped by triangulation from the scanning images produced by a 3D optical scanner. These were followed by simplifying assumptions on which the numerical calculations were based. The numerical calculations were carried out at the operating rotational speeds of the ducted axial fan’s rotor. The course of the numerical calculations is described, and their results are also presented herein. The results are represented on colour maps of stress distribution for selected structural elements of the fan blade. The stress distribution at a blade cross-section was compared to CT scans of the fractures of failed rotor blade airfoils. Final conclusions were developed which show that the design engineering process of fans should feature optimisation of the fan’s efficiency, including the strength and performance parameters, which should include the service life of the fan.

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17

Wang, Chunyang, Zhou Zhou, Rui Wang, and Kelei Wang. "Study on longitudinal stability of ducted vertical take-off and landing fixed-wing UAV." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 39, no. 4 (August 2021): 712–20. http://dx.doi.org/10.1051/jnwpu/20213940712.

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The longitudinal flight stability of the ducted vertical take-off and landing fixed-wing UAV during the flight state of hovering and transition is studied. Firstly, based on the Blade-Element Momentum Theory (BEMT) and experimental data, a coaxial dual-rotor ducted aerodynamic model and a thrust ducted aerodynamic model based on characteristic cross-section calculations are established. The model parameters are identified according to the experimental data. Secondly, a UAV flight dynamics model with thrust duct deflection is established according to the six-degree-of-freedom equations. Finally, the case UAV was used to solve the longitudinal balance and stability analysis of hovering and transition state with the established model method, and compared with the hovering experimental results. The results show that the UAV flight dynamics model combined with the ducted dynamic model established in the article can accurately describe the longitudinal flight stability characteristics of this type of aircraft.

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18

Loeffler, A. L., and J. S. Steinhoff. "Computation of wind tunnel wall effects in ducted rotor experiments." Journal of Aircraft 22, no. 3 (March 1985): 188–92. http://dx.doi.org/10.2514/3.45106.

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19

Farassat, F., and P. L. Spence. "Noise radiation from ducted fans with realistic duct‐rotor coupling." Journal of the Acoustical Society of America 92, no. 4 (October 1992): 2456. http://dx.doi.org/10.1121/1.404530.

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20

Rebeiro, Ronald S., and Andrew M. Knight. "Characterization of a Ducted Rotor Brushless Doubly Fed Reluctance Machine." IEEE Transactions on Energy Conversion 34, no. 1 (March 2019): 79–87. http://dx.doi.org/10.1109/tec.2018.2859906.

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21

Ishihara, Yasuyuki, Won-kyung Jang, Takashi YAMASHITA, Yuki SHIGEMATSU, and Masahumi MIWA. "912 Attitude control of quad rotor helicopter using ducted fan." Proceedings of Conference of Chugoku-Shikoku Branch 2012.50 (2012): 91201–2. http://dx.doi.org/10.1299/jsmecs.2012.50.91201.

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22

Cao, Yihua, and Ziwen Yu. "Numerical simulation of turbulent flow around helicopter ducted tail rotor." Aerospace Science and Technology 9, no. 4 (June 2005): 300–306. http://dx.doi.org/10.1016/j.ast.2005.01.006.

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Oweis, Ghanem F., David Fry, Chris J. Chesnakas, Stuart D. Jessup, and Steven L. Ceccio. "Development of a Tip-Leakage Flow—Part 1: The Flow Over a Range of Reynolds Numbers." Journal of Fluids Engineering 128, no. 4 (March 2, 2006): 751–64. http://dx.doi.org/10.1115/1.2201616.

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An extensive experimental investigation was carried out to examine the tip-leakage flow on ducted propulsors. The flow field around three-bladed, ducted rotors operating in uniform inflow was measured in detail with three-dimensional laser Doppler velocimetry and planar particle imaging velocimetry. Two geometrically similar, ducted rotors were tested over a Reynolds number range from 0.7×106 to 9.2×106 in order to determine how the tip-leakage flow varied with Reynolds number. An identification procedure was used to discern and quantify regions of concentrated vorticity in instantaneous flow fields. Multiple vortices were identified in the wake of the blade tip, with the largest vortex being associated with the tip-leakage flow, and the secondary vortices being associated with the trailing edge vortex and other blade-wake vortices. The evolution of identified vortex quantities with downstream distance is examined. It was found that the strength and core size of the vortices are weakly dependent on Reynolds number, but there are indications that they are affected by variations in the inflowing wall boundary layer on the duct. The core size of the tip-leakage vortex does not vary strongly with varying boundary layer thickness on the blades. Instead, its dimension is on the order of the tip clearance. There is significant flow variability for all Reynolds numbers and rotor configurations. Scaled velocity fluctuations near the axis of the primary vortex increase significantly with downstream distance, suggesting the presence of spatially uncorrelated fine scale secondary vortices and the possible existence of three-dimensional vortex-vortex interactions.

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Raeisi, Bahram, and Hekmat Alighanbari. "Simulation and analysis of flow around tilting asymmetric ducted fans mounted at the wing tips of a vertical take-off and landing unmanned aerial vehicle." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 15 (July 3, 2017): 2870–97. http://dx.doi.org/10.1177/0954410017716954.

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Tilting ducted fans attached to the wing tips of vertical take-off and landing unmanned aerial vehicles define new applications for these types of aerial vehicles. This new configuration gives vertical take-off and landing unmanned aerial vehicles the ability to hover like helicopters and fly forward like airplanes, which results in using any arbitrary location for take-off and landing combined with increasing range and speed. Furthermore, generating additional lift using asymmetrical shape for the external body of the ducted fans can lead to reducing the wing area and related overall drag, which results in saving more energy. This research provides experimental results from wind tunnel tests in addition to computational fluid dynamics simulations to investigate the advantages of using an asymmetrical tilting ducted fan instead of a symmetrical one. “actuator disk model” combined with the assumption of “constant delivered power” to the propeller were used successfully to calculate the induced velocity to the rotor plane of the ducted fan in the computational fluid dynamics simulations. The effects of the stall and flow separation on the aerodynamic coefficients were also studied and compared for the symmetrical and asymmetrical ducted fans. Both computational fluid dynamics and experimental results showed noticeable improvement in the lift coefficient using an asymmetrical shape for the external body of the tilting ducted fans.

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Akturk, Ali, and Cengiz Camci. "Experimental and Computational Assessment of a Ducted-Fan Rotor Flow Model." Journal of Aircraft 49, no. 3 (May 2012): 885–97. http://dx.doi.org/10.2514/1.c031562.

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Abalakin, I. V., P. A. Bahvalov, V. G. Bobkov, T. K. Kozubskaya, and V. A. Anikin. "Numerical simulation of aerodynamic and acoustic characteristics of a ducted rotor." Mathematical Models and Computer Simulations 8, no. 3 (May 2016): 309–24. http://dx.doi.org/10.1134/s2070048216030030.

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QUARANTA, ERIKA, and DIMITRIS DRIKAKIS. "Noise radiation from a ducted rotor in a swirling-translating flow." Journal of Fluid Mechanics 641 (December 10, 2009): 463–73. http://dx.doi.org/10.1017/s0022112009991972.

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This paper investigates the noise radiation produced by a rotor inside a duct, which is convected by a swirling-translating mean flow. The study is based on an extension of Gennaretti's and Morino's boundary element method to the frequency domain for scattering problems in conjunction with a spinning rotor source model in the presence of a swirl flow. The proposed formulation is validated against exact solutions and is further used to investigate the effects of the translating flow Mach number and swirling flow angular velocity on noise radiation to the far field. The scattered sound is highly affected by the convecting mean flow. The modal content of the scattered field increases when increasing the translating flow Mach number, while a swirling flow leads to a reduction of the mode propagation, if co-rotating with respect to the azimuthal order of the spinning source, or an increase of the modal content, if counter-rotating with respect to the source. In general, the mean translating flow moves the main lobes of the directivity patterns downstream, while in some cases the mean swirling flow neglects this effect and the downstream lobe is completely shifted.

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Cao, Yihua, Ke Chen, and Jian Wang. "Analyses on ducted tail rotor and airfoil aerodynamic characteristics with CFD." Aircraft Engineering and Aerospace Technology 77, no. 1 (February 2005): 62–67. http://dx.doi.org/10.1108/00022660510576055.

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Morris, Scott, Jason Tomko, and David Stephens. "Analysis of sound measurements inside a finite length ducted rotor system." Journal of the Acoustical Society of America 127, no. 3 (March 2010): 1797. http://dx.doi.org/10.1121/1.3384030.

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Benômar, Yassine, Julien Croonen, Björn Verrelst, Joeri Van Mierlo, and Omar Hegazy. "On Analytical Modeling of the Air Gap Field Modulation in the Brushless Doubly Fed Reluctance Machine." Energies 14, no. 9 (April 22, 2021): 2388. http://dx.doi.org/10.3390/en14092388.

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The brushless doubly fed reluctance machine (BDFRM) is receiving an increased amount of attention from the research community thanks to its potential as an alternative drive for variable speed applications, both as motor and generator. Currently, the sizing of the BDFRM in the literature is based on the model of an ideal axially laminated rotor (ALR) and discrepancies are hidden in compensation factors which are in turn tuned with a finite element analysis (FEA). This paper proposes an analytical framework to accurately model the air gap field modulation, and by extension the torque density, of the BDFRM with ducted segmental rotor (DSR) and salient pole rotor (SPR). The results are verified with FEA and validated on a BDFRM prototype.

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Liu, Pin, Norimasa Shiomi, Yoichi Kinoue, Ying-zi Jin, and Toshiaki Setoguchi. "Effect of Inlet Geometry on Fan Performance and Flow Field in a Half-Ducted Propeller Fan." International Journal of Rotating Machinery 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/463585.

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In order to clarify the effect of rotor inlet geometry of half-ducted propeller fan on performance and velocity fields at rotor outlet, the experimental investigation was carried out using a hotwire anemometer. Three types of inlet geometry were tested. The first type is the one that the rotor blade tip is fully covered by a casing. The second is that the front one-third part of blade tip is opened and the rest is covered. The third is that the front two-thirds are opened and the rest is covered. Fan test and internal flow measurement at rotor outlet were conducted about three types of inlet geometry. At the internal flow measurement, a single slant hotwire probe was used and a periodical multisampling technique was adopted to obtain the three-dimensional velocity distributions. From the results of fan test, the pressure-rise characteristic drops at high flowrate region and the stall point shifts to high flowrate region, when the opened area of blade tip increases. From the results of velocity distributions at rotor outlet, the region with high axial velocity moves to radial inwards, the circumferential velocity near blade tip becomes high, and the flow field turns to radial outward, when the opened area increases.

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32

Belloni, Clarissa S. K., Richard H. J. Willden, and Guy T. Houlsby. "A Numerical Analysis of Bidirectional Ducted Tidal Turbines in Yawed Flow." Marine Technology Society Journal 47, no. 4 (July 1, 2013): 23–35. http://dx.doi.org/10.4031/mtsj.47.4.16.

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AbstractThe paper presents a computational study of ducted bidirectional tidal turbines using three-dimensional Reynolds-averaged Navier-Stokes simulations. We model the outer duct as a solid body and use a porous disc to represent the turbine rotor, a simplification that captures changes in linear momentum and thus the primary interaction of the turbine with the flow through and around the duct while greatly reducing computational complexity. The duct is modeled using linearly converging and diverging sections and a short straight pipe at the duct throat.We investigate the performance of bare and ducted turbines and relate these to the flows through the devices. For the ducted turbine under investigation, we show a substantial decrease in power generated relative to a bare turbine of diameter equal to the external diameter of the duct. In the case of ducted turbines with concave duct exteriors, we observe two external flow regimes with increasing turbine thrust: nozzle-contoured and separation dominated regimes. Maximum power occurs within the separation dominated flow regime due to the additional channel blockage created by the external separation.The ducts of ducted tidal turbines have been argued to provide a flow straightening effect, allowing modest yaw angles to be readily accommodated. We present a comparison of bare and ducted turbine performance in yawed flow. We show that while bare turbine performance decreases in yawed flow, ducted turbine performance increases. This is due to both a flow straightening effect and also an increase in effective blockage as ducts present greater projected frontal area when approached nonaxially.

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Zamri, Omar. "CFD Simulation for a New Ducted-Fan UAV Configuration." Applied Mechanics and Materials 110-116 (October 2011): 3434–38. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.3434.

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Ducted-fan unmanned aerial vehicle (UAV) is very beneficial in many civil and military applications. It has a good operational flexibility similar to helicopter. Normally, the ducting of high speed spinning fan is done for several reasons; the duct produces lift, it provides higher static thrust when compared to a bare fan of the same diameter, substantial noise level from a spinning fan or rotor can be suppressed, and it increase the safety level for both of the system and the user. However, the main challenge is to understand the aerodynamic characteristic of this vehicle. In this paper, computational fluid dynamic (CFD) is used to study the airflow and aerodynamic characteristic on a new configuration of ducted-fan UAV.

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Misiorowski, Matthew P., Farhan S. Gandhi, and Assad A. Oberai. "Computational Study of Diffuser Length on Ducted Rotor Performance in Edgewise Flight." AIAA Journal 57, no. 2 (February 2019): 796–808. http://dx.doi.org/10.2514/1.j057228.

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35

Alpman, Emre, Lyle N. Long, and Bruce D. Kothman. "Understanding Ducted Rotor Antitorque and Directional Control Characteristics Part II: Unsteady Simulations." Journal of Aircraft 41, no. 6 (November 2004): 1370–78. http://dx.doi.org/10.2514/1.3704.

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36

Stephens, D. B., and S. C. Morris. "A method for quantifying the acoustic transfer function of a ducted rotor." Journal of Sound and Vibration 313, no. 1-2 (June 2008): 97–112. http://dx.doi.org/10.1016/j.jsv.2007.11.054.

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37

Tomko, Jason R., David B. Stephens, Tom Economon, and Scott C. Morris. "Experiments and analysis of the internal wall pressure of a ducted rotor." Journal of Sound and Vibration 451 (July 2019): 84–98. http://dx.doi.org/10.1016/j.jsv.2018.12.026.

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38

Cao, Chenkai, Guoqing Zhao, Qijun Zhao, and Bo Wang. "Numerical investigation and optimization for interior duct shape of ducted tail rotor." Aerospace Science and Technology 115 (August 2021): 106778. http://dx.doi.org/10.1016/j.ast.2021.106778.

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39

Głowacki, Dominik, Krzysztof Bogdański, and Miroslaw Rodzewicz. "Research on the Rotor of a Ducted Fan Propulsion System of MOSUPS Aircraft Taking into Account Self-Balance during Operation." Solid State Phenomena 240 (August 2015): 191–97. http://dx.doi.org/10.4028/www.scientific.net/ssp.240.191.

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The work concerns the research of a propulsion system for an unmanned aerial vehicle MOSUPS in joined wing configuration. Modeling, analysis and experimental research of a statically unbalanced rotor of a ducted fan propulsion system has been conducted.The aim of the analysis was to determine the critical rotational speeds of the rotor due to the probable excitation of oscillations. Due to the complex geometry, Finite Element Method has been used for the calculations. In the study, the critical frequencies (and also rotational speeds) of the rotor as well as precessional instability, flexibly mounted in the bearings have been calculated. Campbell and SAFE diagrams have been presented.Furthermore, the paper presents the idea for a device for automatic dynamic balancing of the mentioned rotor. A mechanism for changing the position of the correction weights has been developed, allowing for a long term operation of rotating parts without the need to stop the unit and correcting the unbalance.The main motivation for work was to fully understand the working conditions of the propulsion system and dynamic properties of the rotor in order to carry out a proper assessment of their impact on the safe operation of the aircraft.

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40

Alpman, Emre, Lyle N. Long, and Bruce D. Kothmann. "Understanding Ducted Rotor Antitorque and Directional Control Characteristics Part I: Steady State Simulation." Journal of Aircraft 41, no. 5 (September 2004): 1042–53. http://dx.doi.org/10.2514/1.3701.

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41

Stephens, David B., and Scott C. Morris. "Measurements and Modeling of the Self Noise of a Low-Speed Ducted Rotor." International Journal of Aeroacoustics 10, no. 5-6 (October 2011): 613–33. http://dx.doi.org/10.1260/1475-472x.10.5-6.613.

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42

Xu, Chang, Hongguang Jia, and Zaibin Chen. "Simultaneous Robust Control and Sensor Fault Detection for a Ducted Coaxial-Rotor UAV." IEEE Access 7 (2019): 167739–53. http://dx.doi.org/10.1109/access.2019.2952386.

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43

Rebeiro, Ronald S., and Andrew M. Knight. "Design and torque capability of a ducted rotor brushless doubly fed reluctance machine." IET Electric Power Applications 12, no. 7 (May 21, 2018): 1058–64. http://dx.doi.org/10.1049/iet-epa.2017.0759.

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44

Bontempo, Rodolfo, and Marcello Manna. "Effects of Duct Cross Section Camber and Thickness on the Performance of Ducted Propulsion Systems for Aeronautical Applications." International Journal of Aerospace Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/8913901.

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The axisymmetric flow field around a ducted rotor is thoroughly analysed by means of a nonlinear and semi-analytical model which is able to deal with some crucial aspects of shrouded systems like the interaction between the rotor and the duct, and the slipstream contraction and rotation. Not disregarding the more advanced CFD based methods, the proposed procedure is characterised by a very low computational cost that makes it very appealing as analysis tool in the preliminary steps of a design procedure of hierarchical type. The work focuses on the analysis of the effects of the camber and thickness of the duct cross section onto the performance of the device. It has been found that an augmentation of both camber and thickness of the duct leads to an increase of the propulsive ideal efficiency.

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45

Ebus, Tobias, Markus Dietz, and Andreas Hupfer. "Experimental and numerical studies on small contra-rotating electrical ducted fan engines." CEAS Aeronautical Journal 12, no. 3 (May 29, 2021): 559–71. http://dx.doi.org/10.1007/s13272-021-00517-7.

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AbstractElectrical propulsion has been identified as one of the key fields of future research within the aerospace sector. The Institute of Aeronautical Engineering at the Universität der Bundeswehr München aims to contribute to the ongoing development of small-sized electrical ducted fan engines with a thrust in the range of 100 N. A special emphasis is placed on electrically powered contra-rotating fan stages. When compared to a conventional rotor–stator stage, contra-rotating fan stages allow for a more compact design, considering a given pressure ratio, or an increased pressure ratio at a constant fan diameter. Since numerous new aircraft concepts are presently being developed, a high demand for compact and powerful electrically driven engines arises. Electrically driven contra-rotating fan engines provide a high potential in terms of compactness, emissions and efficiency. Using electric motors offers the ability to overcome common issues, such as design and integration of a contra-rotating stage into a gas turbine. An innovative new engine design featuring such a contra-rotating stage is developed and tested at one of the Institute’s test benches for electrical propulsion. Key components are two brushless motors powering the fan stage, one for each rotor. Various operation points are investigated experimentally during an extensive test campaign. Experimental results are compared to results of numerical simulations computed by ANSYS CFX. Results indicate a good agreement between experiment and simulation. The engine is running very smooth throughout all tested operation points. Yet, intensive heating up of the electric motors and high-temperature zone are found to be an issue at higher rotation speeds.

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Mishra, Vinay, and Dr H. K. Paliwal. "Analysis of Airconditioning System Using Single-Rotor Wind Turbine Power, Dual Rotor Wind Turbine Power, and Ducted Dual Rotor Wind Turbine Power As Input to Compressor." Revista Gestão Inovação e Tecnologias 11, no. 4 (July 22, 2021): 2952–63. http://dx.doi.org/10.47059/revistageintec.v11i4.2331.

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As vapor compression refrigeration system is the best-suited system used in the present scenario due to its various advantages, in the present paper MATLAB analysis is done for the analysis of simple VCR to calculate COP and refrigeration effect.in the present paper R134a refrigerant is used as a refrigerant.as we know a certain amount of power is used to drive the compressor input in conventional VCR system uses electrical power to convert into mechanical shaft rotation with certain rotation, power and torque.in this paper specific power torque and rotation is given to the compressor without any electrical motor. the power obtains from an SRWT, DRWT, and DDRWT with specific torque power and rotation. then after analysis is carried out to get the COP and Refrigeration Effect.

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47

Howe, M. S. "Installation effects on the production of blade-vortex interaction noise by a ducted rotor." Journal of Sound and Vibration 156, no. 1 (July 1992): 61–78. http://dx.doi.org/10.1016/0022-460x(92)90812-c.

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48

Kim, Jin, Eric G. Paterson, and Frederick Stern. "RANS Simulation of Ducted Marine Propulsor Flow Including Subvisual Cavitation and Acoustic Modeling." Journal of Fluids Engineering 128, no. 4 (December 11, 2005): 799–810. http://dx.doi.org/10.1115/1.2201697.

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High-fidelity Reynolds-averaged Navier Stokes (RANS) simulations are presented for the ducted marine propulsor P5206, including verification and validation (V&V) using available experimental fluid dynamics data, and subvisual cavitation, and acoustics analysis using the modified Rayleigh-Plesset equation along the bubble trajectories with a far-field form of the acoustic pressure for a collapsing spherical bubble. CFDSHIP-IOWA is used with the blended k−ω∕k−ε turbulence model and extensions for a relative rotating coordinate system and overset grids. The intervals of V&V analysis for thrust, torque, and profile averaged radial velocity just downstream of rotor tip are reasonable in comparison with previous results. The flow pattern displays the interaction and merging of the tip-leakage and trailing edge vortices. In the interaction region, multiple peaks and vorticity are smaller, whereas in the merging region, there is better agreement with the experiment. The tip-leakage vortex core position, size, circulation, and cavitation patterns for σi=5 also show good agreement with the experiment, although the vortex core size is larger and the circulation in the interaction region is smaller. The simulations indicate globally minimum Cp=−σi=−8.8 on the suction side of the rotor tip at 84% chord from the leading edge and locally minimum Cp=−6.4 in the tip-leakage vortex at 8% chord downstream of the trailing edge, whereas EFD indicates σi=11 and the location in the tip-leakage vortex core 50% chord downstream of the trailing edge. Subvisual cavitation and acoustics analysis show that bubble dynamics may partly explain these discrepancies.

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Zanforlin, Stefania, Fulvio Buzzi, and Marika Francesconi. "Performance Analysis of Hydrofoil Shaped and Bi-Directional Diffusers for Cross Flow Tidal Turbines in Single and Double-Rotor Configurations." Energies 12, no. 2 (January 16, 2019): 272. http://dx.doi.org/10.3390/en12020272.

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With the aim of finding efficient solutions for cross flow turbine (CFT) bi-directional diffusers able to harvest non perfectly rectilinear tidal currents, a 2D CFD analysis of ducted CFTs was carried out with focus on the effects of diffuser shape and yaw angle. The HARVEST hydrofoil shaped diffuser, equipped with a pair of counter-rotating turbines, and a bi-directional symmetrical diffuser were compared in terms of coefficient of power (CP), torque ripple, overall thrust on diffuser and wake characteristics. Slightly better CP were predicted for the symmetrical diffuser, due to the convergent walls that address the flow towards the blade with a greater attack angle during early and late upwind and to the viscous interactions between the turbine wakes and strong vortices shed by the diffuser. A CP’s extraordinary improving resulted when yaw increased up to 22.5° for the hydrofoil shaped and up to 30° for the symmetrical diffuser. Similar behaviour in yawed flows also occurred in case of a ducted single rotor, demonstrating that it is a characteristic of CFTs. The insertion of a straight throat in the diffuser design proved to be an effective way to mitigate torque ripple, but a CP loss is expected.

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50

Zhou, Zeyang, Jun Huang, and Nana Wu. "Acoustic and radar integrated stealth design for ducted tail rotor based on comprehensive optimization method." Aerospace Science and Technology 92 (September 2019): 244–57. http://dx.doi.org/10.1016/j.ast.2019.06.003.

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Journal articles on the topic 'Ducted Rotor'

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