Experimental Investigation of the Turbulent Aerodynamic Environment Produced by a Generic Ship

Sydney, Anish; Ramsey, Joseph; Kimmel, Kevin

doi:10.2514/6.2016-1071

Cited by 15 publications

(2 citation statements)

References 3 publications

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“…center of flight deck).Velocity and RMS of velocity fluctuations profiles at x/L=0.708 show that the low Re simulation differs significantly from the model-scale and full-scale Re number simulations in the recirculation region behind the superstructure. The increase in RMS of velocity fluctuations seen at z/L=0.12-0.15 for the full-scale Re is due to the high level of RMS generated at the front of the superstructure being convected into the flight deck region, this is similar to the results reported inSydney et al (2016). At x/L=0.883 the low Re simulation still shows differences in the streamwise velocity profile with a larger boundary layer and the negative vertical velocity is about -0.03 larger in the region close to the flight deck.…”

supporting

confidence: 87%

“…The DES simulations were also capable of matching the shedding frequencies and turbulent power measured in the wind tunnel experiments. A more recent study done by Sydney et al (2016) used particle image velocimetry (PIV) to analyze the turbulent flow of the SFS2 airwake. The study showed that each of the backward facing steps generated a shear layer as well as a region of recirculation which has significant three-dimensional variations.…”

Section: Analysis Of the Airwakementioning

confidence: 99%

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Ship Airwakes in Waves and Motions and Effects on Helicopter Operation

et al. 2020

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This thesis focuses on the effects of wave-induced motions on the airwake of a ship and on the operation of a helicopter in the airwake. While the topic is broad, efforts are concentrated on understanding fundamentals of the ship's airwake structure at varying Reynolds (Re) numbers without motions, using available experimental data for validation of the computational fluid dynamics (CFD) methodology used, and on studying the effects of waves and motions on the airwake of a ship and a helicopter operating above a ship's flight deck in full-scale. The static ONR Tumblehome (ONRT) ship geometry with a solid boundary representative of the free surface is simulated at three different Re numbers, 3.2x10 4 , 1x10 6 , and 1.3x10 8. Validation is performed against experimental measurements at model-scale Re=1x10 6. Full-scale simulations of the ONRT are carried out in head winds and regular waves approximately equivalent to conditions seen at sea states 3 and 6. Effects of waves and motions are isolated for both sea states using simulations with combinations of waves and motions, waves and no motions, no waves with motions, and no motions or waves. A triple velocity decomposition is conducted in order to quantify changes in the airwake due to motions and waves. The operation of rotorcraft in the ONRT airwake is analyzed using one-way and two-way coupling approaches. The one-way coupling approach uses the velocity field data from the full-scale ONRT simulations and disk actuator theory to calculate thrust fluctuations for three different rotor sizes. The results of the one-way coupling approach show that the smallest rotor is much more affected by small scale turbulence, while small scale fluctuations are filtered out by larger rotor diameters. In the twoway coupling approach, a helicopter based on the Sikorsky SH-60 hovering above the flight deck is simulated, including explicitly moving grids to discretize the main rotor, tail rotor, and fuselage. This method captures the effects of the interaction between the rotor downwash and the v ONRT airwake. The study shows that for the mild conditions of sea state 3 the motions have little effect on the airwake behavior. At sea state 6 the airwake behavior is significantly altered, which is reflected in the resulting forces on the helicopter body operating in this condition. vi

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confidence: 87%

Section: Analysis Of the Airwakementioning

confidence: 99%