Topic
Pitching moment
About: Pitching moment is a research topic. Over the lifetime, 3213 publications have been published within this topic receiving 38721 citations.
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TL;DR: In this paper, a case study on the supersonic flow around the lateral jet controlled missile has been performed and case studies have been performed by comparing the normal force coefficient and the moment coefficient of a missile body.
37 citations
TL;DR: In this paper, a comparison of flow between an FRS and a typical FRS was conducted to evaluate the effect of rotational moment on the FRS's aerodynamic behavior, and the results showed that the aerodynamic force depends on nondimensional variables, including flapping amplitude, mean angle of attack, pitching amplitude, ratio of period of flapping to rotation motion n, and Reynolds number.
Abstract: A flapping rotary wing is a novel layout for micro air vehicle design. A computational fluid dynamics method is employed to understand the unsteady aerodynamic behavior of such a layout at a low Reynolds number. A comparison of flow between an flapping wing and a typical flapping rotary wing is conducted to evaluate the effect of rotational moment. Although the mean lift of the flapping wing is close to zero, a large mean rotational moment can drive the wing to rotate. A large mean lift coefficient can be obtained when the wing begins to rotate, but the mean rotational moment coefficient starts to decrease. The leading-edge vortex is attached to the wing surface until it moves to the trailing edge, despite the negative spanwise flow near the tip. The aerodynamic force depends on nondimensional variables, including flapping amplitude, mean angle of attack, pitching amplitude, ratio of period of flapping to rotation motion n, and Reynolds number. An analysis of these nondimensional variables shows that only...
37 citations
01 Jan 1988
TL;DR: In this paper, the aerodynamic force and stability characteristics of flat-plate wings were investigated in a wind tunnel for the cases of two delta wings with respective leading edge sweeps of 70 and 45 degrees, and a rectangular wing whose aspect ratio was equal to that of the 70-deg delta wing.
Abstract: Large-amplitude unsteady motion effects on the aerodynamic force and stability characteristics of flat-plate wings were investigated in a wind tunnel for the cases of two delta wings with respective leading edge sweeps of 70 and 45 deg, and a rectangular wing whose aspect ratio was equal to that of the 70-deg delta wing. Attention was given to the effects of reduced frequency and mean angle of attack. It is found that lags in vortex burst location and separation/reattachment of flow on the upper surface of the wing produced large overshoots and hysteresis loops in normal force and pitching moment coefficients that were a strong function of mean oscillation angle and reduced frequency.
37 citations
TL;DR: In this article, a genetic algorithm was used to minimize the total drag at fixed lift subject to various geometrical and aerodynamic constraints, such as pitch moment, pressure and free-stream Mach number.
Abstract: Ar obust and efficient approach to the multiobjective constrained design, previously developed by the authors, is extended to optimization of three-dimensional aerodynamic wings. The objective is to minimize the total drag at fixed lift subject to various geometrical and aerodynamical constraints. The approach employs genetic algorithms (GAs) as an optimization tool in combination with a reduced-order-models (ROM) method, based on linked local databases obtained by full Navier‐Stokes computations. The work focuses on the following issues: geometrical representation of three-dimensional shapes, handling of sensitive nonlinear constraints such as pitching moment, and the influence of flight conditions on the results of optimization. The method, implemented in the computer code OPTIMAS (Optimization of Aerodynamic Shapes), was applied to the problem of multipoint transonic threedimensional wing optimization with nonlinear constraints. The results include a variety of optimization cases for two wings: a classical test case of ONERA M6 wing and a generic cranked transport-type wing. For the investigated class of problems, significant aerodynamic gains have been obtained. Nomenclature C D = total drag coefficient CL = total lift coefficient C M = total pitching-moment coefficient C p = pressure coefficient M = freestream Mach number N D = dimension of the search space Nws = number of sectional airfoils Q = objective function R/c = relative radius of the airfoil leading edge Re = freestream Reynolds number t/c = relative thickness of airfoil α = angle of attack θ = trailing-edge angle of airfoil
37 citations
TL;DR: In this article, the authors focus on the correlation of surface-film behavior including rivulet formulation with measured values of lift, drag, and moment at angles of attack up to stall and quantify effects of boundary-laye r trips for linking flight and wind-tunnel models in rain.
Abstract: Emphasis is placed on the correlation of surface-film behavior including rivulet formulation with measured values of lift, drag, and moment at angles of attack up to stall. Four regions of surface flow are identified: 1) the droplet-impact, 2) film-convection, 3) rivulet-formation, and 4) droplet-convection regions. The extent that each of these regions covers the airfoil surface changes with incidence and correlates with changes in aerodynamicforce coefficients. Additionally, results quantify effects of the use of boundary-laye r trips for linking flight and wind-tunnel models in rain, and show that surface water phenomena affect laminar-to-turbulent transition in a manner that is inconsistent with the use of transition fixing to increase the effective test Reynolds number. Nomenclature ^wing = wing planform area Cd = drag coefficient, DRAG/^wing C, = lift coefficient, LIFT/^wing Cm — moment coefficient, PITCHING MOMENT/^wing c = chord length Re = Reynolds number based on chord length and freestream velocity a = angle of attack AQ = drag coefficient increment, (Crf)wet - (Cd)dry AC/% = percent change in lift coefficient, 100 x [(Q wet ~ (Q^MQ^ ACm .= moment coefficient increment, (Cw)wet - (Cm)dry
37 citations