Pitching moment

About: Pitching moment is a research topic. Over the lifetime, 3213 publications have been published within this topic receiving 38721 citations.

Experimental results for the Eppler 387 airfoil at low Reynolds numbers in the Langley low-turbulence pressure tunnel

Abstract: Experimental results were obtained for an Eppler 387 airfoil in the Langley Low Turbulence Pressure Tunnel. The tests were conducted over a Mach number range from 0.03 to 0.13 and a chord Reynolds number range for 60,000 to 460,000. Lift and pitching moment data were obtained from airfoil surface pressure measurements and drag data for wake surveys. Oil flow visualization was used to determine laminar separation and turbulent reattachment locations. Comparisons of these results with data on the Eppler 387 airfoil from two other facilities as well as the Eppler airfoil code are included.

Unsteady aerodynamics associated with a horizontal-axis wind turbine

Abstract: The wind turbine industry is currently facing many difficulties constructing efficient wind turbine machines caused by the inability to adequately predict structural loading and power output. Available evidence from wind turbines in a field environment suggests that formation of complex unsteady separated flowfields may be responsible for many aspects of wind turbine component failure. To examine this possibility in more detail, the Combined Experiment was developed. A full-scale wind turbine was constructed and operated in a field environment. The environment chosen was subject to wide variations in wind speed and direction and subsequently generated an extensive set of data for a variety of inflow test conditions. A single wind turbine blade was instrumented with pressure transducers and strain gauges with several data sets collected across a wide spectrum of typical and limiting wind turbine operating conditions. Surface pressure data taken at various spanwise locations along the blade demonstrated highly transient and spatially complex aerodynamic behavior for even the most basic operating conditions. Integrated normal force coefficient data showed enhanced lift values significantly beyond that predicted from steady-state two-dimensional wind-tunnel test data. Surface pressure data and integrated moment coefficient data suggested formation of coherent vortices consistent with the dynamic stall process observed in wind-tunnel tests for pitching wings. The unsteady, three-dimensional aerodynamic behavior for this wind turbine was then discussed and summarized.

Vortex-lattice FORTRAN program for estimating subsonic aerodynamic characteristics of complex planforms

Abstract: Computer program for estimating subsonic aerodynamic characteristics of various aerodynamic configurations is presented. Program represents lifting planforms with vortex-lattice. Specific aerodynamic characteristics to be determined are described. Examples and typical running times of various types of configurations are provided.

2-D and 3-D oscillating wing aerodynamics for a range of angles of attack including stall

Abstract: A comprehensive experimental investigation of the pressure distribution over a semispan wing undergoing pitching motions representative of a helicopter rotor blade was conducted Testing the wing in the nonrotating condition isolates the three-dimensional (3-D) blade aerodynamic and dynamic stall characteristics from the complications of the rotor blade environment The test has generated a very complete, detailed, and accurate body of data These data include static and dynamic pressure distributions, surface flow visualizations, two-dimensional (2-D) airfoil data from the same model and installation, and important supporting blockage and wall pressure distributions This body of data is sufficiently comprehensive and accurate that it can be used for the validation of rotor blade aerodynamic models over a broad range of the important parameters including 3-D dynamic stall This data report presents all the cycle-averaged lift, drag, and pitching moment coefficient data versus angle of attack obtained from the instantaneous pressure data for the 3-D wing and the 2-D airfoil Also presented are examples of the following: cycle-to-cycle variations occurring for incipient or lightly stalled conditions; 3-D surface flow visualizations; supporting blockage and wall pressure distributions; and underlying detailed pressure results

Unsteady flow past an airfoil pitching at a constant rate

Abstract: The unsteady flow past a NACA 0012 airfoil that is undertaking a constant-rate pitching up motion is investigated experimentally by the PIDV technique in a water towing tank. The Reynolds number is 5000, based upon the airfoil's chord and the free-stream velocity. The airfoil is pitching impulsively from 0 to 30 deg. with a dimensionless pitch rate alpha of 0.131. Instantaneous velocity and associated vorticity data have been acquired over the entire flow field. The primary vortex dominates the flow behavior after it separates from the leading edge of the airfoil. Complete stall emerges after this vortex detaches from the airfoil and triggers the shedding of a counter-rotating vortex near the trailing edge. A parallel computational study using the discrete vortex, random walk approximation has also been conducted. In general, the computational results agree very well with the experiment.