ENCIT2012-021 PRELIMINARY STUDY OF AERODYNAMIC HEATING AT HYPERSONIC VEHICLE 14-X - PDF
Thiago Lima de Assunção, Paulo Gilberto de Paula Toro, IEAv, Brazil
Abstract: Vehicles flying at high speeds undergo a process of temperature increase in the wall and surrounding. Knowledge of the phenomenon, as well as determining the intensity, is of paramount importance to the material specification to be used for its manufacture, its thermal protection and also provide telemetry problems generated by ionization of the air. Since this is that this work fits, proposing a methodology for calculating for aerodynamic heating of hypersonic vehicle and also estimating the flow of heat generated in the fly regime.
Keywords:aerodynamic heating; hypersonic; 14-X.
Presentation Schedule: Wednesday, 10:00-10:20. Session: AES1-3. Presenter: Valeria S. Faillace O. Leite.
ENCIT2012-007 AIRFOIL AERODYNAMICS AND AEROACOUSTICS USING COMPRESSIBLE LARGE EDDY SIMULATION - PDF
William Roberto Wolf, João Luiz Filgueiras de Azevedo, IAE, Brazil
Lele Sanjiva, Stanford University, United States
Abstract: The present work concerns the investigation of the broadband noise that arises from the interaction of turbulent boundary layers with an airfoil trailing edge. A compressible large eddy simulation (LES) is conducted for the calculation of nearfield noise sources and farfield acoustic predictions are performed by the Ffowcs Williams-Hawkings (FWH) equation. Flow simulation and acoustic predictions are performed for a NACA0012 airfoil at zero deg. angle of incidence and results are compared to experimental data available in the literature.
Keywords:Airfoil noise; LES; Acoustic analogy.
Presentation Schedule: Tuesday, 15:20-15:40. Session: AES1-1. Presenter: William Roberto Wolf.
ENCIT2012-193 NUMERICAL SIMULATION OF AIRFOILS APPLIED TO UAVS - PDF
Paulo Cézar Pereira Corrêa, Manuel Barcelos, UnB, Brazil
Abstract: This essay aims the process optimization when referred to aeronautical projects. By using mesh generators softwares and simulations made in CFD, the article employs numerical techniques to simulate airfoils and shows that is possible to extract accurated and conservative outcomes when compared to wind tunnel results. The test cases studied were based on the Selig 1223 type of airfoil and developed into the ANSYS platform, whereas by using the ICEM mesh tool, structured meshs were generated and imported to the CFX enviroment, where they could be simulated and analyzed.
Keywords:Airfoils; CFX; ICEM; Selig 1223.
Presentation Schedule: Tuesday, 17:40-18:00. Session: AES1-2. Presenter: Paulo Cézar Pereira Corrêa.
ENCIT2012-207 SIMULTANEOUS IDENTIFICATION OF AERODYNAMIC STATES FOR A TRANSONIC TYPICAL SECTION - PDF
João Henrique Albino de Azevedo, ITA, Brazil
João Luiz Filgueiras de Azevedo, Roberto Gil Annes da Silva, IAE, Brazil
Abstract: The objective of the present work is to study forms of identifying the aerodynamic states, for state space aeroelastic stability analyses in the frequency domain, using high-fidelity CFD codes in an efficient fashion. In particular, there is interest in the use of non-parametric identification techniques in order to obtain the necessary aerodynamic transfer functions from a single unsteady CFD computation. The work implements a single combined input method in order to simultaneously excite the aerodynamic responses in all the system natural modes and, at the same time, allow the output to be split into the contribution of each individual mode to the aerodynamic transfer function. The proposed approach is applied to a NACA 0012 airfoil-based typical section model in transonic flight.
Keywords:System identification; Aerodynamic states; Flutter prediction.
Presentation Schedule: Tuesday, 15:40-16:00. Session: AES1-1. Presenter: Joao Luiz F. Azevedo.
ENCIT2012-253 EXPERIMENTS IN TRANSONIC WIND TUNNEL USING A SUPERSONIC FIRST-THROAT - PDF
Bruno Goffert, ITA, Brazil
João Batista Pessoa Falcão Filho, Guido Pires Arantes Ubertini, IAE, Brazil
Abstract: The purpose of this work is to describe the preliminar experimental data obtained with the supersonic first-throat installed in the Pilot Transonic Wind Tunnel (TTP) of the Aerodynamic Division of the Institute of Aeronautics and Space. It is presented the main components of the wind tunnel, as well as the acquisition systems used to assess the experimental data. A special designed pressure probe with 33 measuring stations was utilized to obtain the Mach number distribution at the test section center line. It was also used 25 pressure taps distributed along the top and bottom walls of the tunnel to obtain the Mach number distribution along the test section walls. The tunnel used injection system in a combined fashion with the continuous operation of the tunnel to reach Mach number 1.3. Mass flow extraction was also used with the re-entry flaps at 5 degrees open to enhance the Mach number uniformity along the test section. The experimental results were compared with other typical wind tunnel experimental data.
Keywords:Supersonic Flow; Transonic Wind Tunnel; Supersonic Nozzle.
Presentation Schedule: Tuesday, 16:20-16:40. Session: AES1-1. Presenter: Guido Pires Arantes Ubertini.
ENCIT2012-255 EVALUATION OF THE EFFECTS OF ILLUMINATION, TEMPERATURE AND PAINTING FINISH IN PSP TECHNIQUE - PDF
Rafael Costa, UNIVAP, Brazil
Ana Cristina Avelar, Falcão Filho João Batista, IAE, Brazil
Abstract: In the present paper results of global pressure measurements on a NACA 12 profile, obtained with pressure sensitive paint (PSP), will be presented and compared with pressure tap measurements with the purpose of analyzing the influence of parameter as illumination efficiency and temperature variation of the air flow during the experiments in the accuracy of the PSP results. The experimental measurements were conducted in the Pilot Transonic Wind Tunnel (PTT) of the Instituto de Aeronáutica e Espaço (IAE) for Mach number values of 0.4, 0.6 and 0.8. It was showed that in a carefully prepared experiment, under appropriated operational conditions, and nice adjustments of the PSP components, the accuracy of the obtained results can be vey good. However, even when the influence of temperature is significant and the illumination condition is not ideal, the behavior of the pressure profile on painted surface can be well estimated.
Keywords:Transonic Wind Tunnel; Pressure Sensitive Paint (PSP); NACA 0012 profile.
Presentation Schedule: Tuesday, 14:20-14:40. Session: AES1-1. Presenter: Ana Cristina Avelar.
ENCIT2012-301 COMPRESSIBILITY IMPACT ON THE AERODYNAMIC SURFACE QUANTITIES OF RAREFIED HYPERSONIC FLOW OVER FORWARD-FACING STEPS - PDF
Paulo H. M. Leite, Wilson F. N. Santos, INPE, Brazil
Abstract: Compressibility effects on hypersonic flow over forward-facing steps have been numerically investigated by using the Direct Simulation Monte Carlo (DSMC) method. The work is motivated by interest in assessing the impact of surface discontinuities on hypersonic configurations in the transition flow regime. The computations were carried out by assuming step frontal-face height from 3 to 5 millimeters and freestream Mach number from 5 to 25 at zero-degree angle of incidence. The results highlight some significant differences on the aerodynamic surface quantities due to variations on the step frontal-face height and on the freestream Mach number. Interesting features observed on pressure, skin friction, and heat transfer coefficients showed that small frontal-face thickness, compared to the freestream mean free path, still has important effects on these properties for the freestream Mach number range investigated.
Keywords:DSMC; Hypersonic flow; Rarefeid; Forward-facing step.
Presentation Schedule: Wednesday, 10:20-10:40. Session: AES1-3. Presenter: Wilson F N Santos.
ENCIT2012-315 DIRECT NOISE COMPUTATION OF LOW AND MODERATE MACH NUMBER FLOWS WITH WAKE INTERACTION - PDF
Bruno Backes, UFSC, Brazil
William Roberto Wolf, João Luiz Filgueiras de Azevedo, IAE, Brazil
Abstract: Direct noise calculations of a model airframe noise problem are conducted in order to assess the effects of wake and boundary layer interaction on aeroacoustics. Simulations of unsteady laminar flows including both noise generation, and its subsequent propagation to the far field, are performed for a two-dimensional configuration composed of a cylinder placed above a NACA 0012 airfoil at 5º angle of incidence. The Reynolds number based on the airfoil chord is set at Re=5000 and the Reynolds number based on the diameter of the cylinder is Re=200. An investigation of freestream Mach number effects on sound radiation is presented for Ma = 0.1, 0.3 and 0.5.
Keywords:Direct noise computation; High-order schemes; Wake interaction.
Presentation Schedule: Wednesday, 09:40-10:00. Session: AES1-3. Presenter: William Roberto Wolf.
ENCIT2012-328 ANALYSIS OF A NACA 0012 PROFILE IN A SMALL SUBSONIC INDUCTION DRIVEN WIND TUNNEL - PDF
Ariane Fassina Bredariol, ITA, Brazil
Alcides Rocha Silva, João Batista Pessoa Falcão Filho, IAE, Brazil
Abstract: The Aerodynamic Division (ALA) from the Institute of Aeronautics and Space (IAE) has recently developed a small wind tunnel driven by induction. Through a test campaign, it was verified the good quality of the flow in the test section, certifying it to perform reliable tests. The tunnel is driven by a mixing chamber which uses a supersonic injector working at Mach number 1.9. As the stagnation pressure varies in the injector up to 10 bar, the flow in the test section is established up to Mach number 0.37. Its test section is square with side length of 0.144 m. In these kinds of installations, it is very common to utilize standard devices to investigate the quality of the flow in the test section, such as Pitot probes, pressure probes, yaw meters, etc. In addition, standard models with simple geometries are frequently used in order to compare the experimental results with theoretical predictions and even with experimental results from other wind tunnels. Tests like these characterize a specific phase nominated calibration phase, in which the main operational characteristics of the installation are assessed. With this aim, an aeronautical profile NACA 0012 was installed in the small wind tunnel, since there are extensive available data in the scientific literature. Pressure taps over the profile surface were done and they were connected to pressure sensors to determine the pressure distribution over the model. The profile was installed vertically in the test section, thereby allowing adjustments to the angle of attack. Near the test section entrance, there is a pressure tap at the tunnel wall to determine the undisturbed Mach number condition. This report describes the main steps undertaken during the test campaign with the NACA 0012 in the small wind tunnel in the range from Mach number 0.15 to 0.37 and angles of attack -5, 0 and +5, being analyzed blockage effects.
Keywords:subsonic wind tunnel; profile NACA 0012; pressure coefficient.
Presentation Schedule: Tuesday, 15:00-15:20. Session: AES1-1. Presenter: Ariane Fassina Bredariol.
ENCIT2012-240 INTERNAL BALANCE DEVELOPMENT FOR DRAG MEASUREMENTS - PDF
Solange de Andrade, João Batista Pessoa Falcão Filho, Bruno Goffert, IAE, Brazil
Abstract: The measurement of steady and fluctuating aerodynamic forces acting on a body is one of the main tasks in wind tunnel experiments. In aerodynamic testing, strain gauge balances will usually be applied as, particularly in the past, the main focus was directed to the measurement of steady forces. During the early years of wind tunnel testing, forces and moments were literally measured through pan-type balances, called internal balances. Nevertheless, technology has advanced since those early days, the term "balance" is still applied to different devices used for force and moment measurements. Internal balances are almost universally used for measurements in supersonic and transonic tunnels and are also becoming popular in subsonic tunnels, indeed they can be used in different wind tunnels, ranging from low-speed to transonic, from short to continuous running time and encompassing cryogenic and high pressure principles. The aim of this project is to manufacture a low cost internal balance, that will be useful in many experimental campaigns, specially in drag measurements, in the Pilot Transonic Wind Tunnel of the Institute of Aeronautics and Space (IAE) from DCTA. Thus, an internal balance was designed and will be properly produced, calibrated and tested, but it is very important that the balance displays high rigidity and low interference between the individual force components so that it is possible to obtain a satisfactory calibration.
Keywords:Force measurements; Internal balance; Strain gages; Wind tunnel testing.
Presentation Schedule: Tuesday, 17:00-17:20. Session: AES1-2. Presenter: Solange de Andrade.
ENCIT2012-288 THE INFLUENCE OF THE SST TURBULENCE MODEL COEFFICIENTS ON DETERMINING THE SHOCK WAVE POSITION OF A TRANSONIC FLOW OVER AN AIRFOIL - PDF
Paulo Arthur Beck, Horácio Antonio Vielmo, UFRGS, Brazil
Abstract: This paper presents a numerical analysis on the influence of the SST turbulence model's diffusion coefficients in determining the position of the shock wave due to a transonic flow over the OAT15A airfoil. The conservation equations for mass and momentum, the turbulence model's equations for the turbulent kinetic energy and the specific dissipation rate, the enthalpy and the internal energy equations modeled the flows. The Finite Volume Method, as implemented by the commercial software Star-CCM+, approximated the flows to a discrete computational domain of O-mesh topology and hexahedral volumes, generating a system equations solved using a coupled approach. A mesh independency study verified the computation accuracy. The numerical results referenced experimental data found in literature in order to validate the numerical results. The shock wave location, the drag coefficient and the lift coefficient have been computed with greater accuracy by choosing values for the turbulence model diffusion coefficients that are realizable and yet constrained to values which produce correct near wall solution.
Keywords:SST Turbulence Model; Finite Volumes Method; Shock Wave Position; OAT15A; Star-CCM+.
Presentation Schedule: Tuesday, 16:00-16:20. Session: AES1-1. Presenter: Paulo Arthur Beck.
ENCIT2012-325 PRESSURE DISTRIBUTIONS ON AN AGARD MODEL IN A TRANSONIC WIND TUNNEL USING PSP TECHNIQUE - PDF
Andre Ribeiro de Barros Aguiar, Cayo Prado Fernandes Francisco, UFABC, Brazil
Ana Cristina Avelar, João Batista Pessoa Falcão Filho, IAE, Brazil
Jessica Jia Ling Hsu, UNIP, Brazil
Abstract: The TTP (Pilot Transonic Wind Tunnel) of the IAE (Institute of Aeronautics and Space) is a modern installation and completely operational but, since it is a relatively new installation, new technologies and procedures are being agregated and special tests are needed to as verify its reliability in comparison with other wind tunnel installations. Among many testing devices used to assess the flow behavior in the test section of a transonic wind tunnel, standard models are very useful because they can represent a more complete test assessment as the final aerodynamic parameters are verified. The AGARD association (Advisory Group for Aerospace Research and Development) has created some very useful standard models which are now very popular because of the great amount of compiled data in the scientific literature. The models are used as an inter-laboratorial tool to compare wind tunnel performances. Standard Model C will be used in the tests undertaken in the TTP because it has good transonic behavior. In this approach pressure distribution over the model will be determined by PSP (Pressure Sensitive Paint) technique to allow a complete surface field of the pressure to be compared with the experimental data from two reliable transonic industrial installations, the AEDC 16' PWT and the NAA 7' TWT wind tunnels. Experimental data to be obtained in TTP with a standard AGARD Model C avaiable in the Aerodynamic Division (ALA) will be compared with the data from the literature to assess possible wall interference effects and atest the tunnel reliability in aeronautical experiments. The results and discussions will be presented in the final version of the present work.
Keywords:AGARD standard model C; Transonic Testing; Pressure Sensitive Paint.
Presentation Schedule: Tuesday, 14:40-15:00. Session: AES1-1. Presenter: Andre Ribeiro de Barros Aguiar.
ENCIT2012-359 VORTEX METHOD SIMULATION OF BLASIUS' FLAT PLATE BOUNDARY LAYER - PDF
Helaine Crispim dos Santos, Victor Santoro Santiago, Gustavo César Rachid Bodstein, UFRJ, Brazil
Abstract: The Vortex Method has been extensively used to simulate external flows around bluff and streamlined bodies. It relies on the discretization of the vorticity field into a cloud of vortex blobs to simulate the convective-diffusive transport of vorticity. Vortex blobs are generated in the neighborhood of the solid wall in order to satisfy the no-slip and the no-penetration boundary conditions, and they move in a lagrangian manner to solve the vorticity transport equation. Despite the tremendous development that this powerful mesh-free technique has recently achieved, the numerical implementation of the wall boundary conditions is currently under intense investigation, since it is intimately connected to the vorticity generation process in the vicinity of the body surface. In this paper we describe an efficient two-dimensional vortex method algorithm, with emphasis on a new model for the vortex creation near the surface that increases the accuracy of the simultaneous implementation of the wall boundary conditions. We employ the Adaptive Fast Multipole Method to calculate the induced velocities and the Corrected Core-Spreading Method to simulate the vorticity diffusion in the boundary layer and wake. The method is second-order accurate in space when gaussian vortex blobs are used and second-order accurate in time when the Adams-Bashforth scheme is used to march the integration process in time. The algorithm is tested against the well-known two-dimensional, incompressible boundary-layer flow over a flat plate. The observed agreement between the numerical results and the exact Blasius solution indicates that the algorithm provides an excellent representation of the vorticity field.
Keywords:vortex method; corrected core-spreading method; adaptive fast multipole method; Blasius flat-plate boundary layer; wall boundary conditions.
Presentation Schedule: Tuesday, 17:20-17:40. Session: AES1-2. Presenter: Helaine Crispim dos Santos.