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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24 Jun 2002
TL;DR: In this article, a seamless procedure from CAD data to grid generation is developed to treat the complex configuration of the NAL airplane piggybacked on a rocket for ascending flight and its separation process from the rocket booster is efficiently simulated by the overset unstructured grid method.
Abstract: The present paper describes the numerical methods to compute flows around the NAL Scaled Supersonic Airplane in ascending flight and its separation process from the rocket booster. The Euler equations are solved on unstructured tetrahedral grid. A seamless procedure from CAD data to grid generation is developed to treat the complex configuration of the NAL airplane piggybacked on a rocket for ascending flight. The separation process of the airplane from the rocket is efficiently simulated by the overset unstructured grid method. Comparisons of the computed results with the experiments show good agreements in the lift and pitching moment histories. It is also shown that the small parts attached between the rocket and the airplane significantly change the aerodynamic coefficients of the airplane at transonic regime.
42 citations
TL;DR: In this article, the authors used sliding mesh technology to simulate the relative motion between a wing-in-ground-effect craft and wavy ground and analyzed the aerodynamic characteristics and flowfield.
Abstract: The flow around a wing-in-ground-effect craft flying at α=3 deg and α=9 deg over flat and wavy ground is simulated and investigated by using ANSYS FLUENT, employing the compressible Reynolds-averaged Navier–Stokes equations and the Spalart–Allmaras turbulence model. The sliding mesh technology is used to simulate the relative motion between the wing-in-ground-effect craft and wavy ground. The effects of the wavy ground, flight height, and angle of attack on the aerodynamic characteristics and flowfield are analyzed in detail. The aerodynamic forces are found to be periodic when the wing-in-ground-effect craft flies over wavy ground. The aerodynamic forces over both flat and wavy ground vary with flight height in the same pattern. As the flight height reduces, the lift, drag, and nose-down pitching moment all increase at both angles of attack (α=3 deg and α=9 deg); however, the lift-to-drag ratio increases for all flight heights at α=3 deg, while it first increases and then decreases at α=9 deg. Redu...
41 citations
TL;DR: In this paper, the aerodynamic characteristics of the Gurney flap were comprehensively investigated in terms of the performance requirements for a helicopter rotor by using two-dimensional Navier-Stokes equations.
Abstract: In the present study, the aerodynamic characteristics of the Gurney flap were comprehensively investigated in terms of the performance requirements for a helicopter rotor by using two-dimensional Navier-Stokes equations. To this end, with the rotor operating flow conditions in mind, the static aerodynamic characteristics of the Gurney flap are thoroughly compared with those of the clean airfoil at various Mach numbers, incidences, and Gurney flap heights. Next, to understand the general dynamic stall features of the airfoils with the Gurney flap, a series of parametric studies are performed with respect to oscillating frequency and amplitude, and the correlations of the aerodynamic coefficients are obtained by using the dynamic stall function of Bousman. It is concluded that there exists some optimum Gurney flap heights, which minimize the drag and pitching moment while maximizing the lift coefficient and lift-to-drag ratio at the same time. In the present study, the 2% Gurney flap would be a good compromise to satisfy all the major rotorcraft design criteria.
41 citations
TL;DR: In this paper, an oscillating NACA 0015 airfoil with pre-scheduled trailing-edge flap motion control was investigated by using particle image velocimetry (PIV).
Abstract: The flow around an oscillating NACA 0015 airfoil with prescheduled trailing-edge flap motion control was investigated by using particle image velocimetry (PIV). Aerodynamic load coefficients, obtained via surface pressure measurements, were also acquired to supplement the PIV results. The results demonstrate that upward flap deflections led to an improved negative peak pitching moment coefficient C
m,peak, mainly as a consequence of the increased suction pressure on the lower surface of the flap. The behavior of the leading-edge vortex (LEV) was largely unaffected. Its strength was, however, reduced slightly compared to that of the uncontrolled airfoil. No trailing-edge vortex was observed. For downward flap deflection, the strength of the LEV was found to be slightly increased. A favorable increase in C
l,max, as a consequence of downward flap-induced positive camber effects, accompanied by a detrimental increase in the nose-down C
m,peak, due to the large pressure increase on the lower surface of the flap, was also observed.
41 citations
01 Jun 1949
TL;DR: In this article, the boundary-layer and stalling characteristics on an NACA 64A006 airfoil section at a Reynolds number of 5,800,000 were presented.
Abstract: Report presenting the boundary-layer and stalling characteristics on an NACA 64A006 airfoil section at a Reynolds number of 5,800,000. Data included measurements of lift, drag, and pitching moment, chordwise distributions of pressure, visual studies of the boundary-layer flow, and surveys of the static-pressure and velocity distribution within the boundary layer. Results regarding force and moment characteristics, pressure distributions, and boundary-layer characteristics are provided.
41 citations