Ring-Vortex Panel Method for the Uniformly Loaded Propeller with Axisymmetric Hub

AIAA Journal ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 496-500 ◽  
Author(s):  
Rodolfo Bontempo ◽  
Marcello Manna
Keyword(s):  
Panel Method ◽  
Ring Vortex

scholarly journals Aspects of the Application of a Three Dimensional Panel Method Tool in the Design of a Light Aircraft

2005 ◽  
Author(s):  
Paulo Henriques Iscold Andrade De Oliveira ◽  
Marcos Vinícius Bortolus
Keyword(s):  
Three Dimensional ◽  
Panel Method

Vortex evolution in a round jet

1968 ◽  
Vol 31 (3) ◽  
pp. 435-448 ◽  
Author(s):  
H. A. Becker ◽  
T. A. Massaro
Keyword(s):  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Ring Vortex ◽  
Acoustic Excitation ◽  
Light Scatter ◽  
Turbulent Eddies ◽  
Cylindrical Vortex ◽  
Highly Sensitive ◽  
Pure Tones ◽  
Axisymmetrical Jet

A study has been made of the varicose instability of an axisymmetrical jet with a velocity distribution radially uniform at the nozzle mouth except for a laminar boundary layer at the wall. The evolutionary phenomena of instability, such as the rolling up of the cylindrical vortex layer into ring vortices, the coalescence of ring vortex pairs, and the eventual disintegration into turbulent eddies, have been investigated as a function of the Reynolds number using smoke photography, stroboscopic observation, and the light-scatter technique.Emphasis has been placed on the wavelength with maximum growth rate. The jet is highly sensitive to sound and the effects of several types of acoustic excitation, including pure tones, have been determined.

Experimental Investigation of the Submarine Crashback Maneuver

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
David H. Bridges ◽  
Martin J. Donnelly ◽  
Joel T. Park
Keyword(s):  
Vortex Structure ◽  
Thrust Force ◽  
Ring Vortex ◽  
Forward Motion ◽  
Compact Structure ◽  
Moment Coefficient ◽  
Different Types ◽  
Out Of Plane ◽  
Direction Opposite ◽  
Relative Flow

In order to decelerate a forward-moving submarine rapidly, often the propeller of the submarine is placed abruptly into reverse rotation, causing the propeller to generate a thrust force in the direction opposite to the submarine’s motion. This maneuver is known as the “crashback” maneuver. During crashback, the relative flow velocities in the vicinity of the propeller lead to the creation of a ring vortex around the propeller. This vortex has an unsteady asymmetry, which produces off-axis forces and moments on the propeller that are transmitted to the submarine. Tests were conducted in the William B. Morgan Large Cavitation Channel using an existing submarine model and propeller. A range of steady crashback conditions with fixed tunnel and propeller speeds was investigated. The dimensionless force and moment data were found to collapse well when plotted against the parameter η, which is defined as the ratio of the actual propeller speed to the propeller speed required for self-propulsion in forward motion. Unsteady crashback maneuvers were also investigated with two different types of simulations in which propeller and tunnel speeds were allowed to vary. It was noted during these simulations that the peak out-of-plane force and moment coefficient magnitudes in some cases exceeded those observed during the steady crashback measurements. Flow visualization and LDV studies showed that the ring vortex structure varied from an elongated vortex structure centered downstream of the propeller to a more compact structure that was located nearer the propeller as η became more negative, up to η=−0.8. For more negative values of η, the vortex core appeared to move out toward the propeller tip.

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