scholarly journals Research on Hydrodynamic Characteristics of Blended Wing Body Underwater Glider with Rudder

2020 ◽  
Vol 38 (1) ◽  
pp. 24-30
Author(s):  
Yunlong Ma ◽  
Guang Pan ◽  
Qiaogao Huang ◽  
Jinglu Li
Keyword(s):  
The Body ◽  
Hydrodynamic Characteristics ◽  
Shape Design ◽  
Underwater Glider ◽  
Trailing Edge ◽  
Blended Wing Body ◽  
The Difference ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Rudder Angle

In order to improve the maneuverability and stability of the Blended Wing Body (BWB) underwater glider, the trailing edge rudder is integrated into its shape design in this paper. Through the numerical simulation of CFD, the variation laws of the hydraulic parameters such as lift, drag, lift-to-drag ratio with the angle of attack and rudder angle are given. Compared with the traditional underwater glider, the BWB underwater glider not only has high loading capacity, but also has a maximum lift-to-drag ratio three times that of the former, resulting in higher energy efficiency. At the same time, by adding trailing edge rudders, the maneuverability of the BWB underwater glider is improved, and the lift-to-drag ratio under the same large rudder angle is increased by more than 30% compared with the variable-wing underwater glider. Finally, through the analysis of the numerical results and the cloud image, the difference interaction extent between the rudder and the body of the BWB underwater glider and the traditional torpedo or AUV is illustrated.

CFD Investigation on the Hydrodynamic Characteristics of Blended Wing Unmanned Underwater Gliders With Emphasis on the Control Surfaces

2020 ◽  
Author(s):  
Mukesh Guggilla ◽  
Vijayakumar Rajagopalan
Keyword(s):  
The Body ◽  
Hydrodynamic Characteristics ◽  
Longitudinal Motion ◽  
Low Velocity ◽  
Sweep Angle ◽  
Underwater Gliders ◽  
Naca0012 Airfoil ◽  
Drag Ratio ◽  
Control Surfaces ◽  
Lift To Drag Ratio

Abstract Underwater Gliders are unique buoyancy propelled oceanographic profiling vehicles. Their speed and endurance in longitudinal motion are affected by the symmetry, sweep dihedral angle and span of the control surfaces. In the low-velocity regime, these parameters can be varied to examine the flow around the glider. They also affect the lift-to-drag ratio (L/D) essential for the manoeuvring path in longitudinal and transverse motions. In this paper, the sweep angle of the main wing of a blended wing autonomous underwater glider configuration is varied as 10°, 15°, 30°, 45° and 60° and the resulting hull forms are numerically simulated in the commercial software, STARCCM+. The main wing is a tapered NACA0018 section (taken as per the general arrangement requirement) with 1.5m chord at the root and 0. 1m at the tip. The numerical model is validated using the CFD results of NACA0012 airfoil from Sun.C et al, 2015 [1]. The hydrodynamic forces are obtained by varying the angle of attack (α) of the body from −15° to 15°, for flow velocity of 0.4m/s. The hydrodynamic coefficients (lift-to-drag ratios) and flow physics around the wing are analyzed to arrive at an optimum Lift-to-drag ratio for increased endurance.

scholarly journals A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 828
Author(s):  
Igor Rodriguez-Eguia ◽  
Iñigo Errasti ◽  
Unai Fernandez-Gamiz ◽  
Jesús María Blanco ◽  
Ekaitz Zulueta ◽  
...  
Keyword(s):  
Aerodynamic Coefficients ◽  
Trailing Edge ◽  
High Lift ◽  
Trailing Edge Flaps ◽  
Artificial Neural Network Ann ◽  
Lift And Drag ◽  
Artificial Neuronal Network ◽  
Naca 0012 ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

Hydrodynamic Evaluation of a Generic Sail Used in an Innovative Prawn-Trawl Otter Board

2015 ◽  
Author(s):  
Cheslav Balash ◽  
David Sterling ◽  
Matt Broadhurst ◽  
Arno Dubois ◽  
Morgan Behrel
Keyword(s):  
Degrees Of Freedom ◽  
Design Feature ◽  
Hydrodynamic Characteristics ◽  
Flat Plates ◽  
Successful Operation ◽  
Six Degrees Of Freedom ◽  
Recent Innovation ◽  
Hydrodynamic Evaluation ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In prawn-trawling operations, otter boards provide the horizontal force required to maintain net openings, and are typically low aspect ratio (∼0.5) flat plates operating on the seabed at high angles of attack (AOA; 35–40°). Such characteristics cause otter boards to account for up to 30% of the total trawling resistance, including that from the vessel. A recent innovation is the batwing otter board, which is designed to spread trawls with substantially less towing resistance and benthic impacts. A key design feature is the use of a sail, instead of a flat plate, as the hydrodynamic foil. The superior drag and benthic performance of the batwing is achieved by (i) successful operation at an AOA of ∼20° and (ii) having the heavy sea floor contact shoe in line with the direction of tow. This study investigated the hydrodynamic characteristics of a generic sail by varying its twist and camber, to identify optimal settings for maximum spreading efficiency and stability. Loads in six degrees of freedom were measured at AOAs between 0 and 40° in a flume tank at a constant flow velocity, and with five combinations of twist and camber. The results showed that for the studied sail, the design AOA (20°) provides a suitable compromise between greater efficiency (occurring at lower AOAs) and greater effectiveness (occurring at higher AOAs). At optimum settings (20°, medium camber and twist), a lift-to-drag ratio >3 was achieved, which is ∼3 times more than that of contemporary prawn-trawling otter boards. Such a result implies relative drag reductions of 10–20% for trawling systems, depending on the rig configuration.

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

2016 ◽  
Vol 231 (5) ◽  
pp. 840-858 ◽  
Author(s):  
Yasumasa Watanabe ◽  
Kojiro Suzuki ◽  
Ethirajan Rathakrishnan
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Positive Pressure ◽  
Stagnation Region ◽  
Total Drag ◽  
Hypersonic Speeds ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Blunt Nose

Breathing blunt nose technique is one of the promising methods for reducing the drag of blunt-nosed body at hypersonic speeds. The air, traversed by the bow shock positioned ahead of the nose, at the stagnation region is allowed to enter through a hole at the blunt-nose and ejected at the rear part (base region) of the body. This manipulation reduces the positive pressure over the stagnation regions of the nose and increases the pressure at the base, resulting in reduced suction at the base. The simultaneous manifestation of reducing the compression at the nose and suction at the base regions results in reduction of the total drag. The drag reduction caused by the breathing blunt nose technique has been measured in a Mach 7 tunnel. Also, the drag and flow field around the blunt-nosed body, with and without breathing hole, has been computed. The aerodynamic characteristics of the breathing blunt nose model obtained experimentally are compared with the CFD results. It is found that the breathing results in 5% reduction in drag. The lift coefficient also comes down for the model with breathing nose. But the lift-to-drag ratio is found to be the same for both the cases; the blunt-nosed body with and without nose-hole.

Two-dimensional impervious sails: experimental results compared with theory

1984 ◽  
Vol 144 ◽  
pp. 445-462 ◽  
Author(s):  
B. G. Newman ◽  
H. T. Low
Keyword(s):  
Reynolds Number ◽  
Dynamic Instability ◽  
Two Dimensional ◽  
Poor Agreement ◽  
Trailing Edge ◽  
Small Incidence ◽  
Visualization Experiments ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Edge Flow

Experiments have been made on quasi two-dimensional sails of small camber and at small incidence. Four excess-length ratios have been tested at a Reynolds number of 1.2 x 105. The results for lift, tension, centre of lift, maximum camber and its position, and leading- and trailing-edge membrane angles have been compared with existing inviscid theories and show poor agreement in general. This is attributed to leading- and trailing-edge flow separations as indicated by supplementary flow-visualization experiments. The optimum incidences in particular are much greater than the theoretical value of 0°. Luffing occurs at slightly negative incidences and appears to be a dynamic instability. The highest lift-to-drag ratio obtained was 16.5 on a membrane with an excess-length ratio of 0.03.

CFD Approach to Modelling Hydrodynamic Characteristics of Underwater Glider

2019 ◽  
Vol 2019 (4) ◽  
pp. 32-45
Author(s):  
Kamila Stryczniewicz ◽  
Przemysław Drężek
Keyword(s):  
Flow Behavior ◽  
Equations Of Motion ◽  
Vertical Plane ◽  
Dynamic Modelling ◽  
The Body ◽  
Hydrodynamic Characteristics ◽  
Motion Simulation ◽  
Underwater Glider ◽  
Lift And Drag ◽  
Equations Of Motions

Abstract Autonomous underwater gliders are buoyancy propelled vehicles. Their way of propulsion relies upon changing their buoyancy with internal pumping systems enabling them up and down motions, and their forward gliding motions are generated by hydrodynamic lift forces exerted on a pair of wings attached to a glider hull. In this study lift and drag characteristics of a glider were performed using Computational Fluid Dynamics (CFD) approach and results were compared with the literature. Flow behavior, lift and drag forces distribution at different angles of attack were studied for Reynolds numbers varying around 105 for NACA0012 wing configurations. The variable of the glider was the angle of attack, the velocity was constant. Flow velocity was 0.5 m/s and angle of the body varying from −8° to 8° in steps of 2°. Results from the CFD constituted the basis for the calculation the equations of motions of glider in the vertical plane. Therefore, vehicle motion simulation was achieved through numeric integration of the equations of motion. The equations of motions will be solved in the MatLab software. This work will contribute to dynamic modelling and three-dimensional motion simulation of a torpedo shaped underwater glider.

scholarly journals Conceptual Design, Flying, and Handling Qualities Assessment of a Blended Wing Body (BWB) Aircraft by Using an Engineering Flight Simulator

Aerospace ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 51 ◽  
Author(s):  
Clayton Humphreys-Jennings ◽  
Ilias Lappas ◽  
Dragos Mihai Sovar
Keyword(s):  
Static Stability ◽  
Flight Simulator ◽  
Handling Qualities ◽  
Stability And Control ◽  
Flying Qualities ◽  
Blended Wing Body ◽  
And Control ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Mission Profile

The Blended Wing Body (BWB) configuration is considered to have the potential of providing significant advantages when compared to conventional aircraft designs. At the same time, numerous studies have reported that technical challenges exist in many areas of its design, including stability and control. This study aims to create a novel BWB design to test its flying and handling qualities using an engineering flight simulator and as such, to identify potential design solutions which will enhance its controllability and manoeuvrability characteristics. This aircraft is aimed toward the commercial sector with a range of 3000 nautical miles, carrying 200 passengers. The BWB design was flight tested at an engineering flight simulator to first determine its static stability through a standard commercial mission profile, and then to determine its dynamic stability characteristics through standard dynamic modes. Its flying qualities suggested its stability with a static margin of 8.652% of the mean aerodynamic chord (MAC) and consistent response from the pilot input. In addition, the aircraft achieved a maximum lift-to-drag ratio of 28.1; a maximum range of 4,581 nautical miles; zero-lift drag of 0.005; while meeting all the requirements of the dynamic modes.

scholarly journals Effects of Boundary Layer Control Method on Hydrodynamic Characteristics and Tip Vortex Creation of a Hydrofoil

2017 ◽  
Vol 24 (2) ◽  
pp. 27-39
Author(s):  
Parviz Ghadimi ◽  
Araz Tanha ◽  
Navid Nemati Kourabbasloo ◽  
Sasan Tavakoli
Keyword(s):  
Boundary Layer ◽  
Control Method ◽  
Water Injection ◽  
Tip Vortex ◽  
Boundary Layer Control ◽  
Hydrodynamic Characteristics ◽  
Negative Case ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Layer Control

Abstract There is currently a significant focus on using boundary layer control (BLC) approach for controlling the flow around bodies, especially the foil sections. In marine engineering this is done with the hope of increasing the lift - to - drag ratio and efficiency of the hydrofoils. In this paper, effects of the method on hydrodynamic characteristics and tip vortex formation of a hydrofoil are studied. Steady water injection at the tip of the hydrofoil is simulated in different conditions by using ANSYS-CFX commercial software. Validity of the proposed simulations is verified by comparing the obtained results against available experimental data. Effects of the injection on the lift, drag, and lift - to - drag ratio are studied and the ranges within which the injection has the most positive or negative effects, are determined. Furthermore, flow pattern and pressure variation are studied upon the water injection to determine the most positive and negative case and to ascertain the main reasons triggering these phenomena.

Development of an Aeroelastic Flap to Increase the Aerodynamic Efficiency of a Wind Turbine’s Rotor Blade

2016 ◽  
Vol 831 ◽  
pp. 112-116
Author(s):  
Frank Kortenstedde ◽  
Johannes Crombag ◽  
Michael Twardzik ◽  
Julian K.A. Langowski ◽  
Benjamin Stanke
Keyword(s):  
Rotor Blade ◽  
Technological Development ◽  
Energy Yield ◽  
Trailing Edge ◽  
Economic Output ◽  
Reinforced Plastic ◽  
Horizontal Axis Wind Turbines ◽  
Interaction Simulation ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Horizontal-axis wind turbines are sophisticated technical constructions that require modern design methods for further improvement and higher economic output. Thorough understanding of the whole turbine and its components is indispensable for this aim. The technological development in the last decades indicates the progress in this area and shows the potential of optimizations due to the improvement of rotor blade aerodynamics by additional aerodynamic devices. In this project the effect of an aeroelastic flap mounted on the trailing edge of a rotor blade on energy yield was investigated. For this purpose a flexible flap of fiberglass reinforced plastic for the profile at 70% of the rotor blade span has been designed for the trailing edge and analyzed using a 2-way fluid-structure-interaction simulation. In the first step the simulation is reduced to a two-dimensional investigation using the cross-section at 70% diameter of the rotor blade. Compared to an unmodified profile, the aeroelastic flap increases the lift-to-drag-ratio of the profile in an angle of attack range between 3.5° to 9.5°. The aeroelastic flap has a positive effect on the glide ratio, similar to a non-elastic, static flap.

scholarly journals Center Body Airfoil Design for Blended Wing Body Configuration

2018 ◽  
Vol 36 (2) ◽  
pp. 203-210
Author(s):  
Peifeng Li ◽  
Binqian Zhang ◽  
Yujin Tao ◽  
Zhenli Chen ◽  
Dong Li
Keyword(s):  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Static Stability ◽  
Positive Zero ◽  
Pitching Moment ◽  
Trailing Edge ◽  
Edge Loading ◽  
Blended Wing Body ◽  
Drag Ratio ◽  
Center Body

To design the center-body airfoil of a blended wing body configuration, the aerodynamic effects of the symmetrical airfoil, trailing-edge reflexed airfoil, leading-edge loaded airfoil and leading-edge loaded plus trailing-edge reflexed airfoil are investigated based on the constraints of system arrangement. A 150-passenger BWB configuration is studied; for a center-body with symmetrical airfoil, the larger outer-wing geometrical twist should be used to fulfill the positive zero-lift pitching moment according to the design requirements of longitudinal static stability, however, lift to drag ratio shows a big decrease. For leading-edge loaded airfoil, it is difficult to achieve a positive zero-lift pitching moment because of the platform limitation. For trailing-edge reflexed airfoil or leading-edge loaded plus trailing-edge reflexed airfoil, it is easy to achieve ideal design results when reasonably designing the leading-edge loading and trailing-edge unloading. The application of a blended wing body UAV shows that the loss of aerodynamic characteristics is small when adopting the "eagle hook" stealth leading edge that has the characteristics of leading edge loading.

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