Numerical simulation of fairing separation test for hypersonic air breathing vehicle

2016 ◽  
Vol 231 (2) ◽  
pp. 319-325 ◽  
Author(s):  
Ankit Raj ◽  
K Anandhanarayanan ◽  
R Krishnamurthy ◽  
Debasis Chakraborty
Keyword(s):  
Structural Integrity ◽  
Test Results ◽  
Air Breathing ◽  
Aerodynamic Loads ◽  
Pressure Distributions ◽  
Ground Test ◽  
Computational Fluid Dynamics Simulations ◽  
Euler Solver ◽  
Dynamics Simulations ◽  
Flight Hardware

Fairings are provided to cover hypersonic air breathing vehicle to protect it from adverse aerodynamic loading and kinetic heating. Separation dynamics of fairings is an important event in the launch of vehicle. Extensive computational fluid dynamics simulations are carried out for the design of fairings and vehicle and selection of time sequences of various separation events. A ground test of fairing separation is conducted in the sled facility to check the structural integrity and functionality of various separation mechanisms and flight hardware. Simulations have been carried out to study the separation dynamics of fairings at test conditions using grid-free Euler solver to get the aerodynamic loads and the loads are integrated to get the trajectory of fairings. The aerodynamic loads are provided to verify the structural integrity of various components and the trajectory of panels is used in the test planning. The pressure distributions on the vehicle are compared with the test results.

scholarly journals A Lab-Scale Underwater Glider With Flexible Camber Trailing Edge Wings

2021 ◽  
Author(s):  
Yuhong Liu ◽  
Shixun Xu ◽  
Shan Tian ◽  
Hongwei Zhang ◽  
Shihan Deng ◽  
...  
Keyword(s):  
Decisive Role ◽  
Test Results ◽  
Underwater Glider ◽  
Trailing Edge ◽  
Underwater Gliders ◽  
Steer By Wire ◽  
Computational Fluid Dynamics Simulations ◽  
Motion Performance ◽  
Flexible Deformation ◽  
Dynamics Simulations

Abstract Wings are the main source of lift for the underwater gliders (UGs), and play a decisive role in the motion performance of UGs. A lab-scale UG with flexible camber trailing edge wings was proposed and developed to investigate influences of the trailing edge of the wings on the motion performance of UGs. The flexible deformation of the trailing edge was realized by the steer-by-wire actuator. Test results showed that the trailing edge of the wing can realize the maximum upward/downward sloping angles of +16°/-16°. Combining computational fluid dynamics simulations and tank experiments, the glide efficiency and stable margins of the lab-scale UG with variable camber trailing edge wings were obtained. Results showed that the angles of attack corresponding to the minimum lift-to-drag ratios were all negative in cases of downward sloping, and those were all positive in cases of upward sloping. Moreover, the suitable camber of the trailing edge, i.e., downward-sloping trailing edge on descending glides and upward-sloping trailing edge on ascending glides, can not only greatly improve glide efficiency, but also benefit the flight stability. The lift-to-drag ratios of the lab-scale UG with appropriate variable camber trailing edge wings (i.e., on descending glide with downward-sloping trailing edge, and on ascending glide with upward-sloping trialing edge) can increase by at least 10% compared with those with symmetric airfoil.

scholarly journals Experimental and numerical investigations of cooling drag

2017 ◽  
Vol 231 (9) ◽  
pp. 1203-1210
Author(s):  
Teddy Hobeika ◽  
Simone Sebben ◽  
Lennart Löfdahl
Keyword(s):  
Velocity Distribution ◽  
Aerodynamic Drag ◽  
Cooling System ◽  
Good Prediction ◽  
Test Results ◽  
Cooling Flow ◽  
Computational Fluid Dynamics Simulations ◽  
Flow Through ◽  
Mass Flows ◽  
Dynamics Simulations

As the target figures for CO2 emissions are reduced every year, vehicle manufacturers seek to exploit all possible gains in the different vehicle attributes. Aerodynamic drag is an important factor that affects the vehicle’s fuel consumption, and its importance rises with the shift from the New European Driving Cycle to the Worldwide harmonized Light vehicles Test Cycle which has a higher average speed. In order to reduce vehicle drag, car manufacturers employ the use of grill/spoiler shutters which reduces the amount of air going through the vehicle’s cooling system, also known as cooling flow, thus reducing both its cooling capability and the resultant cooling drag. This paper investigates the influence of different grill blockages on the cooling flow through the radiator of a Volvo S60. By modifying the engine bay and radiator, load cells are used to measure the force acting on the radiator core while the velocity distribution across the radiator core is measured using pressure probes. These values are analyzed and compared to different vehicle configurations and grill inlet designs. A number of test configurations are reproduced in Computational Fluid Dynamics simulations and compared to the test results. For some grill configurations, the simulations provide a good prediction of mass flow and velocity distribution; however a clear discrepancy is present as the grill blockages increase. On the other hand, the force acting on the radiator core was well predicted for all configurations. This paper discusses the different parameters affecting cooling flow predictions such as wind tunnel blockage and measurement grid discretization by comparing radiator forces and mass flows. In addition, the changes on overall vehicle forces are discussed with the radiator force put in context with cooling drag.

scholarly journals Development and Flight Test Results of a Small UAS Distributed Flush Airdata System

2018 ◽  
Vol 35 (5) ◽  
pp. 1127-1140 ◽  
Author(s):  
Roger J. Laurence ◽  
Brian M. Argrow
Keyword(s):  
Angle Of Attack ◽  
Feedforward Neural Networks ◽  
Flight Test ◽  
Unmanned Aircraft ◽  
Wind Instruments ◽  
Test Results ◽  
Alternative Approach ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Relative Wind

AbstractSmall unmanned aircraft systems (sUAS) have proven their effectiveness for measuring both the inertial and aircraft-relative wind. One of the more common aircraft-relative wind instruments is the multihole probe (MHP). While the MHP is accurate and simple to use, two main drawbacks exist: 1) the MHP airdata system can cost several times that of the sUAS and 2) the probe itself is often exposed to damage during routine operations. Flush airdata systems (FADS) are an alternative approach and utilize pressure ports flush with the aircraft surface. This removes any external components, thereby mitigating the risk of damage to the airdata system. The work presented details the implementation of a FADS for sUAS. Computational fluid dynamics simulations were used to determine the port locations of the FADS. Airframe locations were sorted based on the total sensitivity over a range of angles of attack and sideslip. The FADS was calibrated in flight using an onboard MHP. Multilayer feedforward neural networks were employed to produce estimates of the angle of attack and sideslip, while static and stagnation ports on the fuselage measured airspeed. Results from flight testing show errors in angle of attack and sideslip were unbiased. Additionally, 97.9% of the errors in airspeed were within 1 m s−1 of the MHP, while 93.8% and 87.3% of the angle of attack and sideslip errors, respectively, were within 1°. Flight tests show that a FADS can be calibrated in flight and that it is an effective method for measuring the aircraft-relative wind from small UAS.

Assessing the Antimalarial Potentials of Phytochemicals: Virtual Screening, Molecular Dynamics and In-Vitro Investigations

2019 ◽  
Vol 16 (3) ◽  
pp. 291-300
Author(s):  
Saumya K. Patel ◽  
Mohd Athar ◽  
Prakash C. Jha ◽  
Vijay M. Khedkar ◽  
Yogesh Jasrai ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Integrity ◽  
Md Simulations ◽  
Tylophora Indica ◽  
Multidrug Resistance Protein 1 ◽  
Receptor Complexes ◽  
Resistance Protein ◽  
Dynamics Simulations ◽  
Stable Trajectory

Background: Combined in-silico and in-vitro approaches were adopted to investigate the antiplasmodial activity of Catharanthus roseus and Tylophora indica plant extracts as well as their isolated components (vinblastine, vincristine and tylophorine). </P><P> Methods: We employed molecular docking to prioritize phytochemicals from a library of 26 compounds against Plasmodium falciparum multidrug-resistance protein 1 (PfMDR1). Furthermore, Molecular Dynamics (MD) simulations were performed for a duration of 10 ns to estimate the dynamical structural integrity of ligand-receptor complexes. </P><P> Results: The retrieved bioactive compounds viz. tylophorine, vinblastin and vincristine were found to exhibit significant interacting behaviour; as validated by in-vitro studies on chloroquine sensitive (3D7) as well as chloroquine resistant (RKL9) strain. Moreover, they also displayed stable trajectory (RMSD, RMSF) and molecular properties with consistent interaction profile in molecular dynamics simulations. </P><P> Conclusion: We anticipate that the retrieved phytochemicals can serve as the potential hits and presented findings would be helpful for the designing of malarial therapeutics.

scholarly journals Aerodynamic analysis of uphill drafting in cycling

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
T. van Druenen ◽  
B. Blocken
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Speed ◽  
Scientific Literature ◽  
Sensitivity Analyses ◽  
Air Resistance ◽  
Wind Tunnel Measurements ◽  
Aerodynamic Effect ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

AbstractSome teams aiming for victory in a mountain stage in cycling take control in the uphill sections of the stage. While drafting, the team imposes a high speed at the front of the peloton defending their team leader from opponent’s attacks. Drafting is a well-known strategy on flat or descending sections and has been studied before in this context. However, there are no systematic and extensive studies in the scientific literature on the aerodynamic effect of uphill drafting. Some studies even suggested that for gradients above 7.2% the speeds drop to 17 km/h and the air resistance can be neglected. In this paper, uphill drafting is analyzed and quantified by means of drag reductions and power reductions obtained by computational fluid dynamics simulations validated with wind tunnel measurements. It is shown that even for gradients above 7.2%, drafting can yield substantial benefits. Drafting allows cyclists to save over 7% of power on a slope of 7.5% at a speed of 6 m/s. At a speed of 8 m/s, this reduction can exceed 16%. Sensitivity analyses indicate that significant power savings can be achieved, also with varying bicycle, cyclist, road and environmental characteristics.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

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