applications
Dolphin: tail fin (flukes) thrust evaluation
dolphin length: 2.5 m ; oscillating/undulating freq.: 3Hz ; speed: 12kt
'Gray’s Paradox' Solved:
researchers discover secret of speedy dolphins.
(Rensselaer Polytechnic Institute)
researchers discover secret of speedy dolphins.
(Rensselaer Polytechnic Institute)
In 1936, zoologist James Gray estimated the drag dolphins must overcome to swim faster than 20 miles an hour.
Gray said dolphins lacked the muscles to swim so fast, and yet they did. This is known as Gray’s Paradox...
researchers have now determined that dolphins produce 212 pounds of thrust.
DPIV (Digital Particle Image Velocimetry) is used to track and measure the water flow around Primo, a retired U.S. Navy bottlenose dolphin.
The Journal of Experimental Biology (2014)
Measurement of hydrodynamic force generation by swimming dolphins using bubble DPIV
Frank E. Fish, Paul Legac, Terrie M. Williams and Timothy Wei
Vortex generated by a large amplitude fluke stroke from a swimming dolphin.
Velocity vectors are colored and based on vorticity, and the mean rise of the bubbles has been subtracted.
The white box is the control volume used to determine the circulation of the vortex, in this case Γ = 0.19 m2/s
and T = 700 N. The field of view is 1.2 m wide and 0.95 m high. There are 78 and 62 vectors in the horizontal
and vertical directions, respectively. The spacing between vectors is ~1.56 cm. Each vector is assigned a color
corresponding to the local vorticity or fluid rotation rate, ω. Colors indicate the magnitude of ω, where red
corresponds to positive or counterclockwise rotation (ω ≥ 15.0 s-1) and blue indicates negative or clockwise rotation.
The largest velocity magnitude in the image is ~67 cm/s, located just to the right of the tail vortex center; the
maximum vorticity value at the vortex core is 17.5 s-1.
Aircraft or dolphin ?
Rapier X-25: full UAS aerodynamics - PaMS vs OpenFOAM
full aircraft polar
wing-rake-aileron CL – CMy contribution
tail-ruddervator CL – CMy contribution
Rapier X-25: ailerons and ruddervators maneuver and lateral gust
Military aircraft: effect of the propeller wake on the vertical and horizontal tail before starting the take-off roll with lateral wind
wind from right: 18 m/s
roll over torque time history
roll over torque vs lateral wind
Light twin-engine aircraft: effect of the propeller wakes on the wing lift distribution
real aircraft and numerical model
aerodynamic load
In flight refueling: effect of the tanker wake on the receiver lift distribution
tanker-receiver configuration
lift coefficient variation
Business Jet: rolling and heaving motion with lateral wind
Stratofly: from the delta wing to the stratospheric flight
delta wing model
delta wing - lift coefficient
stratofly model
stratofly - pressure coefficient
Turboprop: effect of the combined propeller-wing wake on fuselage and vertical tail at cruise condition
reference config., without propellers
(non symmetric VTAIL)
(non symmetric VTAIL)
with propellers, without wing
with propellers, with lifting wing
UAV tiltrotor: unsteady aerodynamics (copter mode > tilt > plane mode) of a rough tiltrotor model
Vertical Axis Wind Turbine: effect of gust
swept area 8x10m2 , design power 30kW
typical gust-speed-power-TRS time history
performance
blade apparent and AoA @ wind=11m/s
blade forces @ wind=11m/s
Horizontal Axis Wind Turbine: effect of the oscillating wind
swept area 26m2 , design power 5kW
wind: 6m/s +/-5deg
Contra Rotating Open Rotor: aerodynamic analysis at typical sea-level take-off conditions
Flight speed @ see level: 68 m/s (M=0.2)
AoA: 0deg, 20deg
Rotors: diam. 4.27 m, 8 blades
Rotational velocitiy: 1029 rpm (Mtip=0.69)
AoA: 0deg, 20deg
Rotors: diam. 4.27 m, 8 blades
Rotational velocitiy: 1029 rpm (Mtip=0.69)
AoA = 0deg
1 revolution thrust coefficient
AoA = 20deg
1 revolution thrust coefficient
MiniTransat 6.50: hull hydrostatics and stability
hull stability curves
MiniTransat 6.50: aerodynamics of sails
pressure load on sails and apparent wind on streamlines
Aeroelasticity: PaMS-Nastran coupling
UAV joined wing
Car and Bus aerodynamic interference
The Dumned Hunchback: historical aircraft
'Damned hunchback'
It is unclear whether the nickname was genuine or invented by the fascist propaganda.
For sure, the Royal Navy experienced how dangerous and effective the Italian three-engined bomber could be
when pushed in attack by skilled and aggressive crews.
Born as a fast liner, the Savoia Marchetti S.79 'Sparviero' made its first flight back in 1934, and evolved in a fast bomber. It gained fame in the pre-war years through records and competitions, especially with the 'Sorci Verdi' (green rats) squadron. They wan the Paris-Damascus-Istres, placing three airplanes in the first three positions. It deserved, amongst others, the appreciation of Charles Lindberg.
In the urge of the war the S.79 became a torpedo-bomber, role that fitted it more than expected and where it became more famous.
Much of the credit goes to the dedication of the crews: until June 1943 they sank 84 ships and damaged 94 more.
Born as a fast liner, the Savoia Marchetti S.79 'Sparviero' made its first flight back in 1934, and evolved in a fast bomber. It gained fame in the pre-war years through records and competitions, especially with the 'Sorci Verdi' (green rats) squadron. They wan the Paris-Damascus-Istres, placing three airplanes in the first three positions. It deserved, amongst others, the appreciation of Charles Lindberg.
In the urge of the war the S.79 became a torpedo-bomber, role that fitted it more than expected and where it became more famous.
Much of the credit goes to the dedication of the crews: until June 1943 they sank 84 ships and damaged 94 more.
It wasn't perfect: the bombs were stored vertically in a very limited space; the seat of the bomber was uncomfortable
to say the least; defensive armament was limited in fire power and organization; the design was old-fashioned for
WWII standards, using steel tubes structure, metal and fabric skin for the fuselage and wooden wing.
However it was rugged and faithful, agile for its size, appreciated by its crews and able to withstand heavy damage in combat. And, finally, Italian industry was unable to design a valid successor before the end of hostilities. It was the most widely produced Italian bomber of World War II, with some 1,300 built, remaining in Italian service until 1952.
However it was rugged and faithful, agile for its size, appreciated by its crews and able to withstand heavy damage in combat. And, finally, Italian industry was unable to design a valid successor before the end of hostilities. It was the most widely produced Italian bomber of World War II, with some 1,300 built, remaining in Italian service until 1952.
Eng. Francesco Fortunato