scispace - formally typeset
Search or ask a question
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
More filters
Proceedings ArticleDOI
19 Jun 1995
TL;DR: In this paper, a numerical investigation was carried out to systematically develop airfoils which are changing their shape during operation, with specially designed dynamically deforming airfoil sections the dynamic stall characteristics can successfully be influenced.
Abstract: Airfoil designs for helicopter rotors are based on compromises: On the advancing side the blade encounters high speed transonic flows including moving shock waves, on the retreating side, however, the high incidence of the blade may lead to dynamic stall with strong hysteresis effects in force and moment loops. It is the aim of the present numerical investigation to systematically develop airfoils which are changing their shape during operation. With specially designed dynamically deforming airfoil sections the dynamic stall characteristics can successfully be influenced. Rather small airfoil modifications show already considerable benefits with respect to a reduction of the negative (nose-down) pitching moment peak as well as with the avoidance of negative aerodynamic damping.

12 citations

Journal ArticleDOI
11 Apr 2018
TL;DR: Hu et al. as mentioned in this paper investigated the relationship between the core swirl ratio and the local through-flow coefficient for both Batchelor type flow and Stewartson type flow using a test rig at the University of Duisburg-Essen.
Abstract: In radial pumps and turbines, the centrifugal through-flow in both the front and the back chambers is quite common. It strongly impacts the core swirl ratio, pressure distribution, axial thrust and frictional torque. In order to investigate these relationships experimentally, a test rig was designed at the University of Duisburg-Essen and described in this paper. Based on both the experimental and numerical results, correlations are determined to predict the impacts of the centrifugal through-flow on the core swirl ratio, the thrust coefficient and the moment coefficient. Two correlations respectively are determined to associate the core swirl ratio with the local through-flow coefficient for both Batchelor type flow and Stewartson type flow. The correlations describing the thrust coefficient and the moment coefficient in a rotor-stator cavity with centripetal through-flow (Hu et al., 2017) are modified for the case of centrifugal through-flow. The Daily and Nece diagram distinguishing between different flow regimes in rotor-stator cavities is extended with a through-flow coordinate into 3D. The achieved results provide a comprehensive data base which is intended to support the calculation of axial thrust and moment coefficients during the design process of radial pumps and turbines in a more accurate manner.

12 citations

Journal ArticleDOI
TL;DR: In this paper, a back-flow flap attached to the suction side of an airfoil is investigated in both passively and actively actuated modes for the control of dynamic stall.
Abstract: A back-flow flap attached to the suction side of an airfoil is investigated in both passively and actively actuated modes for the control of dynamic stall. This method of dynamic stall control has low power requirements and no parasitic drag when not actuated. Experiments in a low-speed wind tunnel at 50 m/s were used to characterize the reduction in dynamic stall hysteresis using pressure measurements on the midline airfoil section. It was found that the pitching moment peak is reduced by an average of 25% for all deep stall test cases for active actuation of the flap, while for passive actuation the pitching moment peak is reduced by 19%. In each case the maximum lift remained the same, while the peak drag increased by an average of 2.5% for the active flap, and by 0.9% for the passive flap. With the flap closed at low angles of attack, the reference values of the airfoil are retained.

12 citations

Patent
Heil Edward T1
14 Sep 2016
TL;DR: In this article, a method of controlling an active aerodynamic element for a vehicle includes determining a target position for the active aerodynamics element from a target aerodynamic force, which may be a given value that is provided based on dynamic conditions of the vehicle.
Abstract: A method of controlling an active aerodynamic element for a vehicle includes determining a target position for the active aerodynamic element from a target aerodynamic force, which may be a given value that is provided based on dynamic conditions of the vehicle. The method actuates the active aerodynamic element to the target position and senses an aerodynamic response characteristic of the active aerodynamic element while actuated to the target position. An estimated applied aerodynamic force is determined from the aerodynamic response characteristic, and is compared to the target aerodynamic force. A force error is determined from the comparison of the estimated applied aerodynamic force and the target aerodynamic force, and a modified position for the active aerodynamic element is determined from the force error and the target aerodynamic force. The active aerodynamic element is actuated to the modified position.

12 citations

Proceedings ArticleDOI
07 Jan 1991
TL;DR: The influence of the canard on the wing flow field, including canard-wing vortex interaction and wing vortex breakdown, is investigated in this article, where the thin-layer Navier-Stokes equations are solved for the flow about a coplanar close-coupled canardwing-body configuration at a transonic Mach number of 0.90 and at angles of attack ranging from 0 to 12 degrees.
Abstract: The thin-layer Navier-Stokes equations are solved for the flow about a coplanar close-coupled canard-wing-body configuration at a transonic Mach number of 0.90 and at angles of attack ranging from 0 to 12 degrees. The influence of the canard on the wing flowfield, including canard-wing vortex interaction and wing vortex breakdown, is investigated. A study of canard downwash and canard leading-edge vortex effects, which are the primary mechanisms of the canard-wing interaction, is emphasized. Comparisons between the computations and experimental measurements of surface pressure coefficients, lift, drag and pitching moment data are favorable. A grid refinement study for configurations with and without canard shows that accurate results are obtained using a refined grid for angles of attack where vortex burst is present. At an angle of attack of approximately 12 deg, favorable canard-wing interaction which delays wing vortex breakdown is indicated by the computations and is in good agreement with experimental findings.

12 citations


Network Information
Related Topics (5)
Reynolds number
68.4K papers, 1.6M citations
82% related
Boundary layer
64.9K papers, 1.4M citations
79% related
Turbine
106.6K papers, 1M citations
79% related
Laminar flow
56K papers, 1.2M citations
78% related
Turbulence
112.1K papers, 2.7M citations
77% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202353
202294
202168
202076
201983
201886