Examinando por Autor "Barroso, Estela"

Mostrando 1 - 10 de 10

Restringido
A comparative analysis of helicopter recovery maneuvers on a SFS by means of PIV and balance measurements
(Elsevier, 2023-05-23) Matías García, J. C.; Bardera, Rafael; Franchini, Sebastián; Barroso, Estela; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
The flow field around a frigate is complex due to flow detachments, high velocity gradients, and flow unsteadiness. These flow patterns can endanger helicopter operations around frigates and increase pilot workload above the flight deck. This paper contains a comparative analysis of three different recovery maneuvers: an approach from the stern in the centerline plane (S); a diagonal maneuver (D); and an L-shaped maneuver. The comparison is made using wind tunnel tests with a scaled frigate and a motorized helicopter. For the three maneuvers, velocity contours around the helicopter with Particle Image Velocimetry are obtained. An internal balance is also used to obtain forces and moments on the helicopter during the flight path of the maneuvers. Those measurements show that the wake of the ship mostly affects longitudinal and thrust forces. In addition, pitch torque is highly reduced when the helicopter is behind the frigate superstructure, and the roll moment is also important when the wind angle increases. In the end, an estimation of pilot workload is presented to conclude that L-shaped maneuver is the best for 0° and small WOD angles and D or S recoveries for moderately high negative WOD angles.
Acceso Abierto
Calibration of a 3-Component External Balance for MAVs Wind Tunnel Research
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-12-02) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Sor, Suthyvann; Matías García, J. C.; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
This paper presents a 3-component external balance, specifically designed, built, and calibrated at the National Institute for Aerospace Technology (INTA) for measuring aerodynamic forces on Micro Aerial Vehicles in the wind tunnel. The balance employs high-precision strain gauge cells as its load-sensing elements, strategically positioned in a metallic structure to measure lift force, aerodynamic drag force, and pitching moment. The entire calibration process of the balance, including the mathematical formulation to derive the calibration matrix and the calibration bench designed and manufactured for this purpose, is detailed in this paper. Moreover, the complete analysis of component interferences of the aerodynamic components and an assessment of the uncertainties inherent in the system are presented.
Acceso Abierto
CFD study of the effect of leading-edge tubercles on the aerodynamic characteristics of a small UAV based on eppler 186 airfoils
(Elsevier, 2024-09-12) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA)
A numerical analysis is carried out to evaluate the aerodynamic characteristics of a small Unmanned Aerial Vehicle (UAV) whose wings are modified to incorporate sinusoidal leading edges (tubercles). This UAV has a rectangular wing composed of Eppler 186 airfoils. The aerodynamic characteristics of four UAV configurations varying the wavelength and amplitude along the wingspan are evaluated using Computational Fluid Dynamics (CFD). Results are compared with the baseline case, that is, without leading-edge tubercles. The wing configu rations with tubercles exhibited increased lift at high angles of attack and delayed stall. The configuration with maximum amplitude (a = 0.05c) and minium wavelength (λ = 0.25c) achieved an increase up to 17 % in the maximum lift coefficient and delayed the stall up to the angle of attack of 20◦ compared to the baseline case.
Acceso Abierto
Computational Study of Aerodynamic Effects of the Dihedral and Angle of Attack of Biomimetic Grids Installed on a Mini UAV
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-12-29) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Instituto Nacional de Técnica Aeroespacial (INTA); Ministerio de Defensa de España
In this paper, a numerical analysis of a biomimetic unmanned aerial vehicle (UAV) is presented. Its wings feature three grids at the tip similar to the primary feathers of birds in order to modify the lift distribution over the wing and help in reducing the induced drag. Numerical analysis using computational fluid dynamics (CFD) is presented to analyze the aerodynamic effects of the changes in dihedral and angle of attack (with respect of the rest of the wing) of these small grids at the tip. The aerodynamic performances (lift, drag, and efficiency) and rolling capabilities are obtained under different flight conditions. The effects of changing the dihedral are small. However, the change in the grid angle of attack increases aerodynamic efficiency by up to 2.5 times when the UAV is under cruise flight conditions. Changes to the angle of attack of the grids also provide increased capabilities for rolling. Finally, boundary values of the pressure coefficient and non-dimensional velocity contours are presented on the surfaces of the UAV, in order to relate the aerodynamic results to the aerodynamic patterns observed over the wing.
Restringido
Effect of the incident wind angle in a frigate with Coanda active flow control
(Elsevier, 2023-06-01) Matías García, J. C.; Bardera, Rafael; Barroso, Estela; Rodríguez Sevillano, A.; Instituto Nacional de Técnica Aeroespacial (INTA)
The aerodynamic environment around frigates can be complex. This can cause helicopter pilots operating on frigates to face risky situations during the recovery maneuver. In this paper, the introduction of active flow control using Coanda effect has been tested to improve flow characteristics above a frigate flight deck. Wind tunnel tests with Particle Image Velocimetry (PIV) have been performed in order to analyze the effectiveness of introducing Coanda effect at the hangar at four different wind over deck conditions. Applying Coanda effect on the upper part of the frigate hangar the re-attachment distance, and the recirculation areas are reduced. When the Coanda effect is applied also on the sides, the flow recirculation can be completely eliminated, especially for WOD angles different from 0°. The profiles of velocities at the height where the helicopter rotor operates are also corrected, making them uniform and similar to the free stream velocity. In exchange, there is an increase in turbulence intensity close to the hangar, without affecting the rest of the flight deck. The results have shown that Coanda effect clearly improves the aerodynamics over the flight deck where the helicopter operates, and it could help to increase the safety of helicopter operations around frigates.
Restringido
Experimental and numerical simulations of simple frigate with suction flow control over the deck
(Elsevier, 2021-09-15) Bardera, Rafael; Matías García, J. C.; Barroso, Estela; Instituto Nacional de Técnica Aeroespacial (INTA)
The air wake generated behind a frigate superstructure is a very complex and unsteady three-dimensional flow characterized by highly turbulent flow structures with great velocity gradients that result in flow separation over the flight deck where helicopter erations take a significant role. Naturally, this turbulent flow should be removed or, at least, reduced as maximum as possible to avoid accidents during the interaction between frigates and helicopters. This paper involves experimental and numerical analysis on a simple frigate model (SFS2) to understand and simulate the adverse effect of the turbulent flow of the air wake over the deck and tries to minimize it as with active flow control. The experimental study has been performed in the Low Speed Wind Tunnel nº1 of nstituto Nacional de T´ecnica Aeroespacial ‘‘Esteban Terradas’’ (INTA) with Particle Image Velocimetry (PIV) to obtain the velocity field over the flight deck. The frigate has been tested for the headwind condition of 0◦ (wind aligned with the flight deck) with a elocity of 10 m/s. The active flow control consists on generating suction on the flight deck by a mesh of holes. Several configurations of this suction mesh have been studied according to the diameter and location of holes and suction intensity. The suction mesh configuration with the highest diameter and flow rate presents the greatest aerodynamic improvement. The low-speed area over the deck is reduced from 36% to a minimum of 3%.
Acceso Abierto
From conventional to bioinspired: Evolution of tail surface designs in micro air vehicles
(Elsevier, 2024-12-23) Rodríguez Sevillano, A.; Bardera, Rafael; Barroso, Estela; Matías García, J. C.; López Cuervo, Alejandra; Instituto Nacional de Técnica Aeroespacial (INTA)
The paper presents the evolution of the tail surface design of a micro air vehicle based on adaptive wing geometry. The initial prototype was conceived as a tailless aircraft geometry, waiting for future innovations and stability augmentations. An initial experimental test bench will be presented to characterize the variation of wing profile curvature as a function of the voltage, through MFC actuators. Once these results have been analyzed, the process of conceiving a conventional T-tail was initiated, ultimately evolving toward the proposal of a bioinspired tail based on the tail shape of various birds. The results obtained in wind tunnel tests using PIV techniques will be presented. The results validate the selected tail surface design as an appropriate geometry for a bioinspired micro air vehicle.
Acceso Abierto
Numerical Analysis of Bioinspired Tails in a Fixed-Wing Micro Air Vehicle
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-09-08) Bardera, Rafael; Barroso, Estela; Rodríguez Sevillano, A.; Matías García, J. C.
"Bird tails play a key role in aerodynamics and flight stability. They produce extra lift for takeoff and landing maneuvers, enhance wing functions and maintain stability during flight (keeping the bird from yawing, rolling and pitching, or otherwise losing control). This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) involving a Zimmerman wing-body geometry. A selection of five tail shapes of the main types existing in nature is presented, and a parametric analysis is conducted looking into the influence of the most relevant tail geometric parameters to increase the longitudinal static stability of the vehicle. Based on the parametric study, a smaller subset of candidate tail designs are shortlisted to perform a detailed aerodynamic analysis. Then, steady RANS CFD simulations are conducted for a higher-fidelity study of these candidate tail designs to obtain an optimum of each tail type. The criterion for selection of the optimum tail configuration is the maximum aerodynamic efficiency, CL /CD , as well as a high longitudinal static stability. The squared-fan tail provides the highest aerodynamic efficiency while maintaining a high longitudinal stability of the vehicle. In conclusion, this paper provides an innovative study of improving longitudinal stability and aerodynamics through the implementation of bioinspired horizontal stabilizers in vehicles with these characteristics."
Acceso Abierto
Numerical analysis of the thermal convection through a flat plate in Martian conditions
(Elsevier, 2024-06-11) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; López Cuervo, Alejandra; Instituto Nacional de Técnica Aeroespacial (INTA)
There are currently several investigations being developed around Mars, primarily focused on the aerodynamics of drones and the study of atmosphere flow and Martian soil with the assistance of the Perseverance rover. Several phenomena in the Martian atmosphere can complicate flow measurements, and the Multi Mission Radioisotope Thermoelectric Generator (MMRTG) at the rear of the rover can introduce additional uncertainty to the measurements. These measurements are conducted with the system called MEDA, which is located at the front of the rover, under its head. Therefore, it is considered of interest to carry out a preliminary study to determine the feasibility of performing tests on Earth simulating the Martian atmosphere without the need for a vacuum chamber. This would make it possible to streamline and simplify the methods used. The aim of this work is to perform simulations on a plate, that can be considered as a simplification of the MMRTG heat exchanger system, which is composed of a cylinder with flat fins around it, over free and forced convection to verify whether flow behaviour in Martian conditions can be obtained from dimensional analysis on Earth.
Acceso Abierto
Wind Tunnel Balance Measurements of Bioinspired Tails for a Fixed Wing MAV
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-01-10) Bardera, Rafael; Rodríguez Sevillano, A.; Barroso, Estela; Matías García, J. C.; Sor, Suthyvann; Instituto Nacional de Técnica Aeroespacial (INTA)
"Bird tails play a significant role in aerodynamics and stability during flight. This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) with Zimmerman wing-body geometry. Five configurations of bioinspired horizontal tabilizers are presented. Then, 3-component external balance force measurements of each horizontal stabilizer are performed in the wind tunnel. The Squared-Fan-Shaped Horizontal Stabilizer (HSF-tail) is selected as the optimal horizontal stabilizer that provides the highest aerodynamic efficiency during cruise flight while maintaining high longitudinal stability on the vehicle. The integration of the HSF-tail increases the aerodynamic efficiency by more than 6% up to a maximum of 17% compared to the other alternatives while maintaining the lowest aerodynamic drag value during the cruise phase. Furthermore, balancemeasurements to analyze the influence of the HSF-tail deflection on the aerodynamic coefficients are conducted, resulting in increased lift force and reduced aerodynamic drag with negative tail deflections. Lastly, the experimental data is validated with CFD-RANS steady simulations for low angles of attack, obtaining a relative difference on the measurement around 5% for the aerodynamic drag coefficient and around 10% for the lift coefficient during the cruise flight that demonstrates a high degree of accuracy in the aerodynamic coefficients obtained by external balance in the wind tunnel. This work represents a novel approach through the implementation of a horizontal tabilizer inspired by the structure of the tails of birds that is expected to yield significant advancements in both stability and aerodynamic efficiency, with the potential to revolutionize MAV technology."