The Experts below are selected from a list of 2682 Experts worldwide ranked by ideXlab platform
S. Sunouchi - One of the best experts on this subject based on the ideXlab platform.
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estimating the low speed Downwash angle on an aft tail
40th AIAA Aerospace Sciences Meeting & Exhibit, 2002Co-Authors: W. F. Phillips, Elgin A. Anderson, Jerome Jenkins, S. SunouchiAbstract:A closed-form analytic solution for the Downwash induced on an aft tail by the main wing of an airplane is presented. This ine nite series solution is based on Prandtl’ s classical lifting-line theory and accounts for the effects of wing planform shape, as well as tail position and vortex rollup. The results obtained from the present analysis reduce to the known solution for an elliptic wing. Results for a tapered wing are also presented. This ine nite series solution applies only to a main wing with no sweep or dihedral. However, an approximate correction is presented, which can be used with some caution for swept wings. Results obtained from this analytic solution are compared with other methods and experimental data.
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Estimating the low-speed Downwash angle on an aft tail
Journal of Aircraft, 2002Co-Authors: W. F. Phillips, Elgin A. Anderson, J. C. Jenkins, S. SunouchiAbstract:A closed-form analytic solution for the Downwash induced on an aft tail by the main wing of an airplane is presented. This infinite series solution is based on Prandtl's classical lifting-line theory and accounts for the effects of wing planform shape, as well as tail position and vortex rollup. The results obtained from the present analysis reduce to the known solution for an elliptic wing. Results for a tapered wing are also presented. This infinite series solution applies only to a main wing with no sweep or dihedral. However, an approximate correction is presented, which can be used with some caution for swept wings
Adrian L R Thomas - One of the best experts on this subject based on the ideXlab platform.
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digital particle image velocimetry measurements of the Downwash distribution of a desert locust schistocerca gregaria
Journal of the Royal Society Interface, 2006Co-Authors: Richard J. Bomphrey, Graham K Taylor, Nicholas J Lawson, Adrian L R ThomasAbstract:Actuator disc models of insect flight are concerned solely with the rate of momentum transfer to the air that passes through the disc. These simple models assume that an even pressure is applied across the disc, resulting in a uniform Downwash distribution. However, a correction factor, k, is often included to correct for the difference in efficiency between the assumed even Downwash distribution, and the real Downwash distribution. In the absence of any empirical measurements of the Downwash distribution behind a real insect, the values of k used in the literature have been necessarily speculative. Direct measurement of this efficiency factor is now possible, and could be used to compare the relative efficiencies of insect flight across the Class. Here, we use Digital Particle Image Velocimetry to measure the instantaneous Downwash distribution, mid-downstroke, of a tethered desert locust (Schistocerca gregaria). By integrating the Downwash distribution, we are thereby able to provide the first direct empirical measurement of k for an insect. The measured value of kZ1.12 corresponds reasonably well with that predicted by previous theoretical studies.
W. F. Phillips - One of the best experts on this subject based on the ideXlab platform.
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estimating the low speed Downwash angle on an aft tail
40th AIAA Aerospace Sciences Meeting & Exhibit, 2002Co-Authors: W. F. Phillips, Elgin A. Anderson, Jerome Jenkins, S. SunouchiAbstract:A closed-form analytic solution for the Downwash induced on an aft tail by the main wing of an airplane is presented. This ine nite series solution is based on Prandtl’ s classical lifting-line theory and accounts for the effects of wing planform shape, as well as tail position and vortex rollup. The results obtained from the present analysis reduce to the known solution for an elliptic wing. Results for a tapered wing are also presented. This ine nite series solution applies only to a main wing with no sweep or dihedral. However, an approximate correction is presented, which can be used with some caution for swept wings. Results obtained from this analytic solution are compared with other methods and experimental data.
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Estimating the low-speed Downwash angle on an aft tail
Journal of Aircraft, 2002Co-Authors: W. F. Phillips, Elgin A. Anderson, J. C. Jenkins, S. SunouchiAbstract:A closed-form analytic solution for the Downwash induced on an aft tail by the main wing of an airplane is presented. This infinite series solution is based on Prandtl's classical lifting-line theory and accounts for the effects of wing planform shape, as well as tail position and vortex rollup. The results obtained from the present analysis reduce to the known solution for an elliptic wing. Results for a tapered wing are also presented. This infinite series solution applies only to a main wing with no sweep or dihedral. However, an approximate correction is presented, which can be used with some caution for swept wings
Flemming Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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a near wake model for trailing vorticity compared with the blade element momentum theory
Wind Energy, 2004Co-Authors: Helge Aagaard Madsen, Flemming RasmussenAbstract:A near wake model for trailing vorticity originally proposed by Beddoes for high-resolution helicopter blade vortex interaction computations has been implemented and compared with the usual blade element momentum models used for wind turbine calculations. The model is in principle a lifting line model for the rotating blade, where only a quarter revolution of the wake system behind the blade is taken into account. This simplification of the wake enables a fast computation of the Downwash from the trailed vortex system along the blade using the indicial function method and thus makes it realistic to use the model in aeroelastic time simulations. The Downwash from the shed vorticity is also computed with a fast indicial function algorithm. In particular the model is investigated for use in calculations of aerodynamic damping for the different mode shapes of an operating wind turbine. Numerical results for the Downwash of a wing in straight flow with elliptical circulation are compared with analytical results. Further, the Downwash distribution of a 40 m long rotating blade is computed. Aerodynamic damping of the blade in axial harmonic translation and in the first flapwise mode is computed with the near wake model and compared with the results of a standard momentum model including a model for dynamic inflow. Copyright © 2004 John Wiley & Sons, Ltd.
Pei Wang - One of the best experts on this subject based on the ideXlab platform.
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design of uav Downwash airflow field detection system based on strain effect principle
Sensors, 2019Co-Authors: Hao Zhang, Elizabeth M. Musiu, Zepeng Yang, Pei WangAbstract:Accurate measurement of the Downwash flow field of plant protection unmanned aerial vehicles (UAVs) is essential for analyzing the spatial distribution of droplets. To realize on-line rapid detection of the Downwash flow field of a multi-rotor UAV, a flexible polypropylene detection device based on the principle of full bridge strain effect was proposed. Its performance principle was based on the physical deformation caused by wind pressure. The Fluid Flow and Static Structural modules of ANSYS 16.0 finite element software were used to simulate one-way fluid-solid coupling interaction. The surface of the resistive strain gauge embedded in the flexible detecting structure responded well to wind speed variation, hence it was suitable for Downwash airflow wind field detection. By solving the strain force on the surface of the flexible detection structure, the length and layout of the grating wire of the strain gauge on the surface of the flexible detection structure were optimized. Meanwhile at 4 m·s−1 wind speed, the output voltage at varied bridge flexible acquisition systems in the acquisition card was measured. Results indicated coefficient of variation of 3.67%, 1.63% and 1.5%, respectively, which proved the good data acquisition consistency of the system. Through calibration test, the regression equation for the relationship between output voltage and wind speed for three unique sensor signal measuring circuits was established. The determination coefficients R2 for single bridge, half bridge and full bridge circuits were 0.9885, 0.9866 and 0.9959, respectively. In conclusion, by applying the multi-rotor plant protection UAV test platform, the results indicated the maximum relative error of the wind speed at each sampling point of the system at 1.0 m altitude was below 5.61%. Simulated and measured value had an RMSE maximum error of 0.1246 m·s−1. Moreover, Downwash airflow detection not only has high accuracy but also has high sensitivity. Thus, there is convenience and practicability in the plant protection offered by this approach. The rapid measurement of UAV wind field and the established two-dimensional wind field model can provide a basis for precise application of agricultural aviation.