Thrust Enhancement From Radial Velocity in Squid Inspired Thrusters

2012 ◽  
Author(s):  
Michael Krieg ◽  
Kamran Mohseni
Keyword(s):  
Radial Velocity ◽  
Driving Mechanism ◽  
Low Thrust ◽  
Vortex Ring Formation ◽  
Total Impulse ◽  
Fluid Jets ◽  
Force Range ◽  
And Control ◽  
Thrust Production ◽  
Control Surfaces

Squid and jellyfish generate propulsive forces by successively taking in and expelling high momentum jets of water. This method of propulsion offers several advantages to underwater vehicles/robots. The driving mechanism can be placed internal to the vehicle, reducing the drag associated with an abundance of external thrusters and control surfaces. The thrusters can generate accurate predictable forcing in the low thrust range, while still generating thrust nearly instantaneously over the entire force range. Vortex ring formation dynamics play an important role in creating thrust. It is observed that squid and jellyfish eject fluid jets which are not exactly parallel, and have a contracting velocity in the radial direction. A prototype thruster was developed which generates both parallel and converging propulsive jets. The total impulse of the jet is determined from DPIV techniques to determine the effect a non-zero radial velocity had on thrust production. The radial velocity was observed to increase the total impulse of the jet by 70% for low stroke ratio jets, and 75% for large stroke ratio jets.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

scholarly journals Body Flexibility Enhances Maneuverability in the World’s Largest Predator

2018 ◽  
Vol 59 (1) ◽  
pp. 48-60 ◽  
Author(s):  
P S Segre ◽  
D E Cade ◽  
J Calambokidis ◽  
F E Fish ◽  
A S Friedlaender ◽  
...  
Keyword(s):  
Open Ocean ◽  
The Body ◽  
Long Distance ◽  
Active Surfaces ◽  
Aquatic Locomotion ◽  
And Performance ◽  
And Control ◽  
Blue Whales ◽  
Control Surfaces ◽  
Complex Trajectories

Abstract Blue whales are often characterized as highly stable, open-ocean swimmers who sacrifice maneuverability for long-distance cruising performance. However, recent studies have revealed that blue whales actually exhibit surprisingly complex underwater behaviors, yet little is known about the performance and control of these maneuvers. Here, we use multi-sensor biologgers equipped with cameras to quantify the locomotor dynamics and the movement of the control surfaces used by foraging blue whales. Our results revealed that simple maneuvers (rolls, turns, and pitch changes) are performed using distinct combinations of control and power provided by the flippers, the flukes, and bending of the body, while complex trajectories are structured by combining sequences of simple maneuvers. Furthermore, blue whales improve their turning performance by using complex banked turns to take advantage of their substantial dorso-ventral flexibility. These results illustrate the important role body flexibility plays in enhancing control and performance of maneuvers, even in the largest of animals. The use of the body to supplement the performance of the hydrodynamically active surfaces may represent a new mechanism in the control of aquatic locomotion.

scholarly journals Longitudinal Actuated Abdomen Control for Energy Efficient Flight of Insects

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5480
Author(s):  
Titilayo Ogunwa ◽  
Blake McIvor ◽  
Nurkhairunisa Awang Jumat ◽  
Ermira Abdullah ◽  
Javaan Chahl
Keyword(s):  
Energy Efficient ◽  
Insect Flight ◽  
Design Feature ◽  
Unmanned Aircraft ◽  
Longitudinal Control ◽  
Flight Behaviour ◽  
Aerodynamic Control ◽  
The Cost ◽  
And Control ◽  
Control Surfaces

The actuated abdomens of insects such as dragonflies have long been suggested to play a role in optimisation and control of flight. We have examined the effect of this type of actuation in the simplified case of a small fixed wing aircraft to determine whether energetic advantages exist in normal flight when compared to the cost of actuation using aerodynamic control surfaces. We explore the benefits the abdomen/tail might provide to balance level flight against trim changes. We also consider the transient advantage of using alternative longitudinal control effectors in a pull up flight maneuver. Results show that the articulated abdomen significantly reduces energy consumption and increase performance in isolated manoeuvres. The results also indicate a design feature that could be incorporated into small unmanned aircraft under particular circumstances. We aim to highlight behaviours that would increase flight efficiency to inform designers of micro aerial vehicles and to aid the analysis of insect flight behaviour and energetics.

scholarly journals Design and Control of an Embedded Vision Guided Robotic Fish with Multiple Control Surfaces

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Junzhi Yu ◽  
Kai Wang ◽  
Min Tan ◽  
Jianwei Zhang
Keyword(s):  
Visual Processing ◽  
Vision System ◽  
The Body ◽  
Robotic Fish ◽  
Multiple Control ◽  
Caudal Fin ◽  
Embedded Vision ◽  
And Control ◽  
Control Surfaces ◽  
Pelvic Fin

This paper focuses on the development and control issues of a self-propelled robotic fish with multiple artificial control surfaces and an embedded vision system. By virtue of the hybrid propulsion capability in the body plus the caudal fin and the complementary maneuverability in accessory fins, a synthesized propulsion scheme including a caudal fin, a pair of pectoral fins, and a pelvic fin is proposed. To achieve flexible yet stable motions in aquatic environments, a central pattern generator- (CPG-) based control method is employed. Meanwhile, a monocular underwater vision serves as sensory feedback that modifies the control parameters. The integration of the CPG-based motion control and the visual processing in an embedded microcontroller allows the robotic fish to navigate online. Aquatic tests demonstrate the efficacy of the proposed mechatronic design and swimming control methods. Particularly, a pelvic fin actuated sideward swimming gait was first implemented. It is also found that the speeds and maneuverability of the robotic fish with coordinated control surfaces were largely superior to that of the swimming robot propelled by a single control surface.

scholarly journals Cleansing orthodontic brackets with air-powder polishing: effects on frictional force and degree of debris

2016 ◽  
Vol 21 (4) ◽  
pp. 60-65 ◽  
Author(s):  
Brisa dos Santos Leite ◽  
Nathalia Carolina Fernandes Fagundes ◽  
Mônica Lídia Castro Aragón ◽  
Carmen Gilda Barroso Tavares Dias ◽  
David Normando
Keyword(s):  
Image Analysis ◽  
Comparative Analysis ◽  
Frictional Force ◽  
Orthodontic Treatment ◽  
Orthodontic Brackets ◽  
Wilcoxon Test ◽  
Control Group ◽  
And Control ◽  
Sliding Mechanics ◽  
Control Surfaces

ABSTRACT Introduction: Debris buildup on the bracket-wire interface can influence friction. Cleansing brackets with air-powder polishing can affect this process. Objective: The aim of this study was to evaluate the frictional force and amount of debris remaining on orthodontic brackets subjected to prophylaxis with air-powder polishing. Methods: Frictional force and debris buildup on the surface of 28 premolar brackets were evaluated after orthodontic treatment. In one hemiarch, each bracket was subjected to air-powder polishing (n = 14) for five seconds, while the contralateral hemiarch (n = 14) served as control. Mechanical friction tests were performed and images of the polished bracket surfaces and control surfaces were examined. Wilcoxon test was applied for comparative analysis between hemiarches at p < 0.05. Results: Brackets that had been cleaned with air-powder polishing showed lower friction (median = 1.27 N) when compared to the control surfaces (median = 4.52 N) (p < 0.01). Image analysis showed that the control group exhibited greater debris buildup (median = 2.0) compared with the group that received prophylaxis with air-powder polishing (median = 0.5) (p < 0.05). Conclusion: Cleansing orthodontic brackets with air-powder polishing significantly reduces debris buildup on the bracket surface while decreasing friction levels observed during sliding mechanics.

Marine Applications of the Biomimetic Humpback Whale Flipper

2011 ◽  
Vol 45 (4) ◽  
pp. 198-207 ◽  
Author(s):  
Frank E. Fish ◽  
Paul W. Weber ◽  
Mark M. Murray ◽  
Laurens E. Howle
Keyword(s):  
Leading Edge ◽  
Humpback Whale ◽  
Hydrodynamic Effect ◽  
Technological Advancement ◽  
Transfer Of Technology ◽  
Biomimetic Approach ◽  
Engineered Systems ◽  
Marine Applications ◽  
And Control ◽  
Control Surfaces

AbstractThe biomimetic approach seeks technological advancement through a transfer of technology from natural technologies to engineered systems. The morphology of the wing-like flipper of the humpback whale has potential for marine applications. As opposed to the straight leading edge of conventional hydrofoils, the humpback whale flipper has a number of sinusoid-like rounded bumps, called tubercles, which are arranged periodically along the leading edge. The presence of the tubercles modifies the water flow over the wing-like surface, creating regions of vortex generation between the tubercles. These vortices interact with the flow over the tubercle and accelerate that flow, helping to maintain a partially attached boundary layer. This hydrodynamic effect can delay stall to higher angles of attack, increases lift, and reduces drag compared to the post-stall condition of conventional wings. As the humpback whale functions in the marine environment in a Reynolds regime similar to some engineered marine systems, the use of tubercles has the potential to enhance the performance of wing-like structures. Specific applications of the tubercles for marine technology include sailboat masts, fans, propellers, turbines, and control surfaces, such as rudders, dive planes, stabilizers, spoilers, and keels.

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