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Optimization Of Synthetic Jet Actuator Location For Aerodynamic Drag Reduction Of Backward-Facing Step

Optimization Of Synthetic Jet Actuator Location For Aerodynamic Drag Reduction Of Backward-Facing Step

I declare that this thesis entitled “Optimization of Synthetic Jet Actuator Location for Aerodynamic Drag Reduction of Backward-facing Step” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.

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Review on Aerodynamic Drag Reduction of Vehicles

Review on Aerodynamic Drag Reduction of Vehicles

Vortex generators (VG) is an aerodynamic body permanently fixed on vehicle with a certain angle with flow direction. Generally, VGs are placed in a group to create clock-wise or counter-clockwise vortices (as per their configuration) which add momentum to near wall surface where flow is separated, as a result, the separation is suppressed or shifted further downstream. An extensive experimental studies have been carried out to evaluate the performance of VGs on aerodynamic drag reduction [40]. In this research, three combinations of VGs namely, (i) complete line-22 VGs (ii) 4 VGs on each side (iii) 14 VGs in the centre were used on a modified Ahmed body which is shown in Figure 13. Details of flow structure are captured by PIV and hot-wire anemometry. Parametric studies of VG has also been conducted to figure out the optimum outcome by considering the effect of angle of VG with flow direction, their placement, effect on Re. Among of the tested done with three configurations of VGs, complete line of vortex generators is the most effective as it reduces the drag and lift as 12% and 60%, respectively.

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Aerodynamic Drag Reduction of Emergency Response Vehicles

Aerodynamic Drag Reduction of Emergency Response Vehicles

This paper addresses the aerodynamic drag reduction of vans, which are converted for use as emergency response vehicles (ERVs) to provide patient transport to hospital and within the police service in the UK. There has generally been far less research into aerodynamic improvements for vans [19], however funding constraints arising from the recent financial crisis, coupled with rising fuel prices, have forced public authorities in the UK to address the aerodynamic design of their ERVs. For example, the Yorkshire Ambulance Service Trust (YAST) fleet has 1500 ERVs travelling 40 million miles every year, resulting in the consumption of 4.2 million liters of fuel at a cost of more than £6 million. The YAST, in common with all other Ambulance Service Trusts in the UK, has ambitious targets of reducing CO 2 emissions from its fleet operations (currently set at 30%), and improved aerodynamic design has been identified as a significant potential contributor to achieving substantially reduced fuel consumption and CO 2 emissions.

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Enhancement of Aerodynamic Drag Reduction of Passenger Vehicle using CFD analysis-Review

Enhancement of Aerodynamic Drag Reduction of Passenger Vehicle using CFD analysis-Review

A. AERODYNAMIC: The subject “Aerodynamics” studies with air flow passing over the automobile and also the behavior of air flow with the help of experimental setup like as Wind Tunnel as well as theoretical (analytical or semi analytical) and computational fluid dynamics (CFD) approaches respectively. The term “air” is used in a generic sense. It basically means the flowing gaseous medium which could be air, helium, or any other gas for that matter depending on condition. Anything is passing through air then effect of aerodynamic is shown, like rocket launching, kite flying in sky. Even cars passing through air is also affected by aerodynamics effect [6]. CFD analysis is only efficient tool in order to evaluate specific design parameterization of a generic shape of automobile. Computational Fluid Dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze the problems that involve fluid flows. The analysis of system is associated by means of computer based simulation. Nowadays consume fuel 50% for ground vehicle all over worldwide and affected 60% greenhouse gas affected by the emission of gases from consuming fuel [1]. In recent times increasing the greenhouse effect in global warming world to reduce CO 2

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A Review Paper on Aerodynamic Drag Reduction and CFD Analysis of Vehicles

A Review Paper on Aerodynamic Drag Reduction and CFD Analysis of Vehicles

model of General Motor SUV and tested in the wind tunnel for expected wind conditions and road clearance. Two passive devices, rear screen which is plate behind the car and rear fairing where the end of the car is aerodynamically extended, were incorporated in the model and tested in the wind tunnel for different wind conditions. The conclusion was that rear screen could reduce drag up to 6.5% and rear fairing can reduce the drag by 26%. It was also mentioned that efficiency of rear screens from point of view of drag reducing equally depends on configuration, dimensions and arrangement of screens as well as on model’s rear part configuration. S.M. Rakibul Hassan Et al. (2014) [14] numerical methods

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Aerodynamic Drag Reduction of a Passenger Vehicle by Controlling the Wake Using CFD Analysis

Aerodynamic Drag Reduction of a Passenger Vehicle by Controlling the Wake Using CFD Analysis

With the increase in global warming and harmful emissions coupled with the increasing number of automobile road vehicles moving on highway roads has brought the attention of policy makers to focus on the research to mitigate climate change and also to increase the performance of road vehicles. Due to the current laws which have been reinforced on fuel emissions, scholars and manufacturers have been prompted to work back to back on improving the engine performance or reducing aerodynamic drag of road vehicles to improve fuel economy. This research focus on how aerodynamic drag can be reduced by adding a spoiler at the rear of a passenger vehicle to control the flow. The analysis is done through wind tunnel experiments in combination with CFD software package Fluent 16.0. The addition of a rear spoiler was found to be able to reduce aerodynamic drag but in the wrong run it considerably increased lift.

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Commercial Vehicle Aerodynamic Drag Reduction: (Tipper Truck)

Commercial Vehicle Aerodynamic Drag Reduction: (Tipper Truck)

Therefore the wind current moves specifically between the cab roof redirector and the top of the tipper body, it in this manner cause the air pressure in the cab to trailer crevice to reduction this negative weight being more articulated on the uncovered upper vertical face of the tipper subsequently the front face upper district of the tipper will really lessen that part of drop delivered by the uncovered frontal zone of the tipper, on the other hand the negative weight made by the wind stream over the main edge of the roof bombs quickly, showing early wind stream re connection.

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Review of Research on Vehicles Aerodynamic Drag Reduction Methods

Review of Research on Vehicles Aerodynamic Drag Reduction Methods

Mazyan [29] analyzed the effect of applying drag reducing devices on a sedan, sports utility vehicle (SUV) and a tractor trailer model to improve the fuel consumption of the vehicle. Both RANS (Reynolds-averaged Navier–Stokes equations) and LES are used to analyze the percent drag reduction due to the use of different drag reducing devices. The numerical procedure is first validated against the experimental data for the tractor-trailer model with no drag reducing devices installed. Following the validation, simulations are carried out to investigate the percent drag reduction by installing a modified front head to help the flow transition from the tractor to the trailer, and inventive rear wings that direct the air flow towards the rear of the vehicle where low pressure exists. The tractor trailer results showed a total drag reduction of around 21% when the front and rear drag reducing devices was installed. Huminic et al. [34] presented new results concerning the flow around the Ahmed body fitted with a rear underbody diffuser without endplates, to reveal the influence of the underbody geometry, shaped as a venturi nozzle, on the main aerodynamic characteristics. The study was performed for different geometrical configurations of the underbody, radius of the front section, length and the angle of the diffuser being the parameters, which were varied. Later, based on a theoretical approach, the coefficients of the equivalent aerodynamic resistances of the front section of underbody and diffuser were computed, which help to evaluate the drag due to underbody geometry.

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Diving speeds and angles of a gyrfalcon (Falco rusticolus)

Diving speeds and angles of a gyrfalcon (Falco rusticolus)

The speeds of 47–58 m s −1 reported for 8 of the 11 dives in this study are the highest ever measured for animals with methods of known accuracy. The previous record was 43 m s −1 for a flock of mergansers (Mergus serrator) (Alerstam, 1987). Even so, Kumpan could have gone faster if he had not controlled his speed by increasing drag. For example, the ideal falcon with minimum drag can reach a speed of 72 m s −1 in a 45 ° dive with a vertical drop of 450 m, starting from 15 m s −1 , and speeds of 100 m s −1 or more are plausible in steeper dives with vertical drops of over 1000 m (Tucker, 1998). Kumpan’s dives, however, were controlled maneuvers in which he increased drag in two large and distinct steps: first, to maintain a speed limit after acceleration, and a second time to begin decelerating from the speed limit.

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Reduction Of Drag Forces Of An Aircraft

Reduction Of Drag Forces Of An Aircraft

40 Lift is primarily caused by angle of attack. When positioned in a suitable angle it deflects the incoming air resulting in a force called aerodynamic force which can be resolved into two components lift and drag .Angle of attack can be defined as the angle between the reference line of the body and the direction of fluid flow on the body. Lift primarily takes place due to a principle called as Bernoulli Principle . It states that an increase in speed occurs simultaneously with a decrease in pressure . This principle basically can be derived from the principle of conservation of energy . It states that, in a steady flow the sum of all forms of energy in a fluid along a streamline is the same at all the points at that streamline. Thus the sum of kinetic energy , potential energy and internal energy remain constant.

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Analysis of Car Body Aerodynamics to Reduce Drag Coefficient using CFD Tool

Analysis of Car Body Aerodynamics to Reduce Drag Coefficient using CFD Tool

From analysis it is clear that the flow of air tends to separate without implementation of vortex generators at the back end. Implementation of vortex generators at the back end leads to better control of flow separation and drag reduction thereby improving the overall performance of an automobile. Hence, it can be concluded that aerodynamic stability and fuel economy can be improved by implementation of vortex generators.

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Analysis of Car Body Aerodynamics to Reduce Drag Coefficient using CFD Tool

Analysis of Car Body Aerodynamics to Reduce Drag Coefficient using CFD Tool

From analysis it is clear that the flow of air tends to separate without implementation of vortex generators at the back end. Implementation of vortex generators at the back end leads to better control of flow separation and drag reduction thereby improving the overall performance of an automobile. Hence, it can be concluded that aerodynamic stability and fuel economy can be improved by implementation of vortex generators.

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Design modification on Indian Road Vehicles to Reduce Aerodynamic Drag

Design modification on Indian Road Vehicles to Reduce Aerodynamic Drag

Investing in good aerodynamic styling on new trucks will repay your investment. Manufacturers go to enormous expense using wind tunnels to improve aerodynamic stability and reduce parasitic drag. The truck pictured is an example of good aerodynamic styling and air management. To understand how this styling reduces your fuel consumption look at the simplified diagram below of an articulated truck without any curved edges. Also note that there is a large gap between the tractor and the trailer. Compare this with the well styled tractor and trailer in the second picture. You’ll see that there are fewer areas of turbulence and turbulence causes drag. The second vehicle will use less fuel. Ensure that air can flow easily and smoothly over the shape of your vehicle, by minimizing things that stick out and block the air’s passage. Wherever possible chose smooth sided designs, curved edges, hidden buckles and a close gap between your tractor and your trailer.

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COMPUTATIONAL STUDY OF SUPERSONIC FLOW PAST BLUNTED TANGENT-OGIVE NOSE CONE

COMPUTATIONAL STUDY OF SUPERSONIC FLOW PAST BLUNTED TANGENT-OGIVE NOSE CONE

The Mach number contours clearly depict the structure of bow shock formed near the nose, which comprises strong and weak regions of flow separated by a sonic line through which flow re-accelerates to the supersonic velocity. The corresponding shock locations ahead of the blunted tangent ogive are indicated by the sudden jump in Mach number and static pressure plots. The Mach number plot shows a sharp decrease and the static pressure plot shows a sharp rise for the detached shock. The pressure coefficient as well as aerodynamic drag coefficient decreases with increasing the ogive radius for a fixed bluntness ratio.

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Wind turbine blade design

Wind turbine blade design

An alternative method of propulsion is the use of aerodynamic lift (Table 1), which was utilised without precise theoretical explanation for over 700 years in windmills then later in vintage aircraft. Today, due to its difficult mathematical analysis, aerodynamics has become a subject of its own. Multiple theories have emerged of increasing complexity explaining how lift force is generated and predicted. Aerodynamic force is the integrated effect of the pressure and skin friction caused by the flow of air over the aerofoil surface [7]. Attributed to the resultant force caused by the redirection of air over the aerofoil known as downwash [8]. Most importantly for wind turbine rotors, aerodynamic lift can be generated at a narrow corridor of varying angles normal to the wind direction. This indicates no decrease in relative wind velocity at any rotor speed (Table 1).

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The relationship between 3 D kinematics and gliding performance in the
southern flying squirrel, Glaucomys volans

The relationship between 3 D kinematics and gliding performance in the southern flying squirrel, Glaucomys volans

Field estimates of glide angle in the closely related and similarly sized northern flying squirrel (Glaucomys sabrinus) averaged 26.8°, corresponding to a mean lift-to-drag ratio of 1.98 (Vernes, 2001), presuming a steady glide. The mean net height loss for these glides was 10.2·m, compared to 4·m in our experiments. It is likely that the squirrels in this study did not launch from a great enough height to reach their minimum glide angle. The expected glide trajectory for mammals begins with a relatively steep glide angle until the animal has reached a sufficiently high speed to maximize its lift. When this steady speed is reached, the glide angle is expected to become constant until the animal is about to land, at which time the animal rises slightly as it rapidly increases its angle of attack in order to orient itself such that it can land on the vertical trunk of the landing tree. In the present study, the squirrels did not exhibit steady glides. According to the predicted glide trajectory described above, the fact that the squirrels in this (6) D

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Numerical study of aerodynamic drag force on student formula car

Numerical study of aerodynamic drag force on student formula car

Numerical study of aerodynamic drag force on student formula car has been made as well. A virtual simulation study has brought a result where inspired student to increase a confident level, especially in the design concept of student formula car that would suggest the best design in future development. From the simulation study also can observe the area which generated turbulence flow, low pressure, high pressure, coefficient of drag, the coefficient of lift, wake area, pressure distribution on the surface, trailing vortices flow, noise study, skin friction drag and pressure drag. In the simulation study revealed that Cd = 0.28 has a tendency to produce aerodynamic student formula car range. Furthermore, from the simulation study also found that the separated flow occurs whenever the student formula car moving above 50km/h. The more blunt design the vehicle, the higher coefficient of drag will produce.

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Static Aeroelasticity Considerations in Aerodynamic Adaptation of Wings for Low Drag

Static Aeroelasticity Considerations in Aerodynamic Adaptation of Wings for Low Drag

In this thesis, a methodology has been presented that allows for the calculation of flap angles to reproduce a desired lift distribution and simultaneously mini- mize profile drag. If the desired lift distribution is elliptical, then the induced drag will also be minimized. This methodology includes calculations for the wing twist and accounts for static aeroelastic phenomena, such as flap reversal and flap effectiveness, in the flap angle calculations.

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Optimization and design of an aircraft’s morphing wing tip demonstrator for drag reduction at low speed, Part I – Aerodynamic optimization using genetic, bee colony and gradient descent algorithms

Optimization and design of an aircraft’s morphing wing tip demonstrator for drag reduction at low speed, Part I – Aerodynamic optimization using genetic, bee colony and gradient descent algorithms

It was observed that for the problem of upper-surface air- foil morphing, where there are two parameters to optimize, the three optimization methods found the global optimum area in almost all the cases and situated their results inside that region, with the GD method having the lowest quality results. The Monte Carlo maps show that there was no particular unique solution to the optimization of an airfoil upper- surface, as there was a region in which various combinations of actuator displacements had obtained relatively the same transition point location or drag coefficient value. For any given test case out of the 20 cases, the three algorithms could give three different solutions (where a solution refers to a com- bination of displacements) located inside the global optimum region. Nonetheless, the genetic algorithm has proven its reli- ability and that it obtained similar and even better results than the BC algorithm for most of the test cases, therefore it was

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PROBLEMS IN FLIGHT DYNAMICS AND ITS SOLUTIONS

PROBLEMS IN FLIGHT DYNAMICS AND ITS SOLUTIONS

The mechanics of the flight studies the forces acting on the aircraft in flight, and the reaction of the aircraft to the action of these forces. All aircraft are equipped with a control system that allows the pilot to maneuver and release forces from the control levers on each of the three axes. The aerodynamic moments required to rotate the aircraft are usually realized by deflecting control surfaces that change the curvature of the profile. Control surfaces are located as far as possible from the center of gravity in order to create the maximum control moment.

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