Topic
Pitching moment
About: Pitching moment is a research topic. Over the lifetime, 3213 publications have been published within this topic receiving 38721 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a mathematical model for performance prediction of a high-speed planing hull in forward acceleration motion has been developed, where three degrees of freedom have been considered for solving the problem.
17 citations
TL;DR: In this article, an automated iterative design method was developed by which an airfoil with a substantial amount of natural laminar flow can be designed while maintaining other aerodynamic and geometric constraints.
Abstract: An automated iterative design method has been developed by which an airfoil with a substantial amount of natural laminar e ow can be designed while maintaining other aerodynamic and geometric constraints. Drag reductions have been realized using the design method over a range of Mach numbers, Reynolds numbers, and airfoil thicknesses. The key features of the method are the compressible linear stability analysis code used to calculate N-factors; the ability to calculate a target N-factor distribution that forces the e ow to undergo transition at the desired location; the target pressure/ N-factor relationship that is used to modify target pressures to produce the desired N-factor distribution; and its ability to design airfoils to meet lift, pitching moment, thickness, and leading-edge radius constraints while also being able to meet the natural laminar e ow constraint.
17 citations
TL;DR: In this paper, a clearer understanding of how freestream disturbances affect the aerodynamic forces of helicopter rotors, wind-turbine blades, and maneuvering aircraft is presented.
Abstract: Dynamically moving airfoils are encountered in helicopter rotors, wind-turbine blades, and maneuvering aircraft. A clearer understanding of how freestream disturbances affect the aerodynamic forces...
17 citations
TL;DR: In this article, the effects of pitch phase angle and pitch amplitude on the aerodynamic properties of a two-dimensional (2D) flapping wing executing simple harmonic motion in hovering mode were investigated.
Abstract: This paper reports on a fundamental investigation of the effects of pitching phase angle (ϕ) and pitching amplitude (αA) on the aerodynamics of a two-dimensional (2D) flapping wing executing simple harmonic motion in hovering mode. A force sensor and digital particle image velocimetry were employed to obtain the time-dependent aerodynamic forces acting on the wing and the associated flow structures, respectively. Pitching phase angle ranging from 0° to 360° at three different pitching amplitudes, that is, 30°, 45° and 60°, was studied. Our experimental results revealed that the largest lift and lift/drag ratio were achieved under the condition of advanced pitching (ϕ > 90°). However, further increasing ϕ beyond a certain value would not enhance the average lift any more. In contrast, the delayed pitching (ϕ < 90°) would cause the average lift to decrease and generally the averaged drag to increase, compared to the normal pitching (ϕ = 90°), overall reducing the lift/drag ratio greatly. Our experimental results also supported the findings of Lua et al. (J Exp Fluids 51:177–195, 2011) that there are two kinds of wing–wake interactions, and they can either enhance or reduce lift on the wing depending on the wing motion and the timing of the reverse stroke. Our results show that wing–wake interaction of the first kind normally has an adverse effect on lift generation when the wing is undergoing delayed pitching but has a positive effect on the lift when the wing is undergoing advanced pitching motion. When the ϕ became larger, the second kind of wing–wake interaction, that is, sliding of the leading edge vortex under the wing, will cause the concurrent fall in lift and drag.
17 citations
TL;DR: In this paper, the aerodynamic pitching moment, lift and drag forces acting on a ski-jumper during free flight and landing phases were measured using scaled models in a wind tunnel.
Abstract: The aerodynamic pitching moment, lift and drag forces acting on a ski-jumper during the free flight and landing phases were measured using scaled models in a wind tunnel. Comparisons are made between those meaurements and observations of actual ski-jumps. It is shown that the high angles of incidence (typically α varies from 35° to 55°) adopted by ski-jumpers during free flight is determined by the need to prevent tumbling. Over this range of incidence angles, the opposing moments due to weight distribution and aerodynamic pressure distribution are approximately in equilibrium, and small out-of-balance moments can be accommodated by arm movements. The maximum lift/drag ratio on a ski-jumper in free flight occurs at α ≃ 25°. If it were possible to avoid tumbling at low incidence angles, maximum jump lengths would be achieved at α ≃ 8°.
17 citations