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1
Baydar, Adem. "Hot-wire measurements of compressor blade wakes in a cascade wind tunnel/". Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23254.
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A hot-wire system, with software designed for calibrating and taking data with single, double and triple hot-wire sensors separately, or three probes at once, was verified and used to make wake measurements downstream of a compressor stator blade in a cascade wind tunnel. Using a single hot-wire probe, velocity and turbulence data were obtained in the wake of the controlled-diffusion blade in order to verify LDV data taken in earlier studies. The tests were conducted at three inlet angles from near design incidence towards the expected stall condition at a Mach number of 0.25 and Reynolds number of about 700,000. Wake profiles were obtained from 0.08 to 0.2 chord lengths downstream of the blade. Good agreement was found with LDV measurements. Measurements at the highest incidence angle showed that the wake constituted one third of the flow and yet no separation occurred before the trailing edge on the suction side of the blade. Keywords: Laser doppler velocimeters
2
Hamilton, Christianne Rhea. "Design of Test Sections for a High Enthalpy Wind Tunnel". MSSTATE, 2003. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04082003-114126/.
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This document describes the design of a supersonic and a subsonic test section for a high enthalpy wind tunnel. A streamline is tracked through a supersonic test section using the method of characteristics. The specifics of the design program and the design techniques are illustrated for the supersonic section. The section of the paper dealing with the subsonic nozzle has a greatly diverse nature. This section details the inlet and exhaust restrictions and construction elements for the entire low speed system. The system is currently being set up for testing with the subsonic section, and the supersonic will eventually follow.
3
Sparks, Russell. "A novel six degree of freedom dynamic wind tunnel test facility". Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492066.
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Murray, Kenneth Douglas. "Automation and extension of LDV measurements of off-design flow in a cascade wind tunnel". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25708.
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Tourn, Cremona Silvana Cecilia. "Characterization of a New Open Jet Wind Tunnel to Optimize and Test Vertical Axis Wind Turbines". Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/461079.
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Basat en el creixent interès en les tecnologies ambientals urbanes, l'estudi de turinas d'eix vertical de petita escala mostra desafiaments motivadors. En aquesta tesi, es presenten els criteris de disseny, les característiques i potencialitats d'un nou túnel de vent de secció de prova oberta. Té un àrea de sortida i la broquet del túnel de 1,5 x 1,5 m2, i es pot operar amb velocitats de sortida de 3 m / s a 17 m / s. La caracterització del flux s'ha dut a terme amb tubs pitot calibrats, anemòmetres de cassoletes i anemòmetres de fil calent. Es consideren dues configuracions diferents de l'àrea de prova, amb i sense sostre. Els mesuraments en el rang de velocitats de sortida disponibles mostren que la secció transversal, on les intensitats de velocitat i turbulència mostren un nivell acceptable d'uniformitat, té una àrea de 0,8 x 0,8 m2 i una dimensió de 2 m des de la sortida del broquet del túnel. En aquesta secció de treball, la intensitat màxima de la turbulència és del 4%. La caracterització detallada del flux realitzat indica que el túnel de vent es pot utilitzar per provar models a d'aerogeneradors de petita escala.Basado en el creciente interés en las tecnologías ambientales urbanas, el estudio de turinas de eje vertical de pequeña escala muestra desafíos motivadores. En esta tesis, se presentan los criterios de diseño, las características y potencialidades de un nuevo túnel de viento de seccion de prueba abierta. Tiene un área de salida e la boquilla del túnel de 1,5 x 1,5 m2, y se puede operar con velocidades de salida de 3 m/s a 17 m/s. La caracterización del flujo se ha llevado a cabo con tubos pitot calibrados, anemómetros de cazoletas y anemómetros de hilo caliente. Se consideran dos configuraciones diferentes del área de prueba, con y sin techo. Las mediciones en el rango de velocidades de salida disponibles muestran que la sección transversal, donde las intensidades de velocidad y turbulencia muestran un nivel aceptable de uniformidad, tiene un área de 0,8 x 0,8 m2 y una dimensión de 2 m desde la salida de la boquilla del túnel. En esta sección de trabajo, la intensidad máxima de la turbulencia es del 4%. La caracterización detallada del flujo realizado indica que el túnel de viento se puede utilizar para probar modelos a de aerogeneradores de pequeña escala.
Based on the increasing interest in urban environmental technologies, the study of small scale vertical axis wind turbines shows motivating challenges. In this thesis, we present the design criteria, characteristics and potentials of a new open jet wind tunnel. It has a nozzle exit area of 1.5 x1.5 m2, and it can be operated with exit velocities from 3 m/s to 17 m/s. The characterization of the flow has been carried out with calibrated pitot tubes, cup anemometers, and hot wire anemometers. Two different configurations of the test area, with and without a ceiling, are considered. Measurements in the range of available exit velocities show that the cross section, where the velocity and turbulence intensities show an acceptable level of uniformity, has an area of 0.8 x 0.8 m2 and a streamwise dimension of 2 m from the nozzle exit of the tunnel. In this working section, the maximum turbulence intensity is 4%. The detailed characterization of the flow carried out indicates that the wind tunnel can be used to test small scale models of wind turbines.
6
Dalley, Sam. "Wind tunnel measurements on a low rise building and comparison with full-scale". Thesis, University of Surrey, 1993. http://epubs.surrey.ac.uk/886/.
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Capasso, Michael Anthony. "Construction and wind tunnel test of a 1/12th scale helicopter model". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA288487.
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Hamm, Christopher Eric. "AN ASSESSMENT OF FLOW QUALITY IN AN OPEN TEST SECTION WIND TUNNEL". MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11022009-115210/.
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The subsonic wind tunnel facility at Mississippi State University has been converted to an open test section configuration. An experimental setup was developed which is easily configurable to allow for further research. Measurements of flow quality over select portions of the test section were made to attain a basic understanding of the performance of the new configuration. A program was developed in LabVIEW to control a 3-axis traverse and perform necessary data reduction. The traverse control program was developed to perform data acquisition using a hot-film probe to facilitate the necessary measurements. Data was gathered at two wind tunnel velocity settings over several test section locations. Results of the testing program yielded recommendations on the use of the open configuration. This paper documents the procedure and setup of the testing program to include discussion of the control/data acquisition program and a discussion of the findings and recommendations.
9
James, Ralph William. "The effect of boundary layer blowing in the corner region of a linear compressor cascade wind tunnel". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-05092009-040547/.
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Muthanna, Chittiappa. "The Effects of Free Stream Turbulence on the Flow Field through a Compressor Cascade". Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/28753.
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The flow through a compressor cascade with tip leakage has been studied experimentally. The cascade of GE rotor B section blades had an inlet angle of 65.1º, a stagger angle of 56.9º, and a solidity of 1.08. The final turning angle of the cascade was 11.8º. This compressor configuration was representative of the core compressor of an aircraft engine. The cascade was operated with a tip gap of 1.65%, and operated at a Reynolds number based on the chord length (0.254 m) of 388,000. Measurements were made at 8 axial locations to reveal the structure of the flow as it evolved through the cascade. Measurements were also made to reveal the effects of grid generated turbulence on this flow. The data set is unique in that not only does it give a comparison of elevated free stream turbulence effects, but also documents the developing flow through the blade row of a compressor cascade with tip leakage.
Measurements were made at a total of 8 locations 0.8, 0.23 axial chords upstream and 0, 0.27, 0.48, 0.77, 0.98, and 1.26 axial chords downstream of the leading edge of the blade row for both inflow turbulence cases. The measurements revealed the formation and development of the tip leakage vortex within the passage. The tip leakage vortex becomes apparent at approximately X/ca= 0.27 and dominated much of the endwall flow. The tip leakage vortex is characterized by high streamwise velocity deficits, high vorticity and high turbulence kinetic energy levels. The result showed that between 0.77 and 0.98 axial chords downstream of the leading edge, the vortex structure and behavior changes.
The effects of grid generated turbulence were also documented. The results revealed significant effects on the flow field. The results showed a 4% decrease in the blade loading and a 20% reduction in the vorticity levels within tip leakage vortex. There was also a shift in the vortex path, showing a shift close to the suction side with grid generated turbulence, indicating the strength of the vortex was decreased. Circulation calculations showed this reduction, and also indicated that the tip leakage vortex increased in size by about 30%. The results revealed that overall, the turbulence kinetic energy levels in the tip leakage vortex were increased, with the most drastic change occurring at X/ca= 0.77.Ph. D.
11
Ying, Pei. "Aerodynamic analysis of a novel wind turbine for an omni-flow wind energy system". Thesis, University of Hertfordshire, 2016. http://hdl.handle.net/2299/17355.
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The purpose of this research is to propose a novel wind turbine for an omni-flow wind energy system and investigate its aerodynamic performance. The geometry of the novel wind turbine is based upon the impulse turbine technology which has been successful in wave energy. In this study, both numerical and experimental studies were conducted to evaluate the aerodynamic features of this wind turbine. The numerical method was validated by a comparison between numerical and experimental results over a range of tip speed ratios. Results obtained from experiments and simulations indicate that the proposed wind turbine can be employed. Additionally, on the basis of the analyses performed, this new wind turbine has the potential for having a good startup feature, which means that this wind turbine can be suitable for applications in an urban environment. As an important component, the stator of this wind turbine can increase the passing flow velocity by 20%. Meanwhile, the passing flow direction also can be optimised by the stator. Aerodynamics of the wind turbine was analysed under the non-uniform flow condition, because the flow is non-uniform inside the omni-flow wind energy system. It was found that the maximum power coefficient of such a turbine under the non-uniform flow condition is lower than that under the uniform flow condition. Due to the non-uniform flow, the blades experience different flow velocities, and as a consequence, undergo different aerodynamic loads during one operation cycle. Thus the generated torque and thrust on a blade are subjected to frequent and periodical changes. Influences of the geometrical parameters on the aerodynamic characteristics of this wind turbine were investigated. From the initial study, it was found that changes of hub-to-tip ratios, numbers of blades, aerofoils and numbers of guide vanes, can significantly affect the II power performance. Additionally, the wind turbine obtained high values of maximum torque coefficients with changing geometrical parameters.
12
Westin, Michelle Fernandino. "Aeroelastic modeling and experimental analysis of a flexible wing for wind tunnel flutter test". Instituto Tecnológico de Aeronáutica, 2010. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1121.
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The objective of this work is to investigate the flutter phenomena experimentally, which will unify high aspect ratio wings design for wind tunnel flutter tests (Dowell and Tang, 2002), cheaper aeroelastic models construction and a procedure used by Sheta, Harrand, Thompson and Strganac (2002) to identify the flutter onset power spectral density versus the frequency. Initially, an experimental model developed by Dowell and Tang (2002) has been considered as a baseline model and, from this point, two new models with different wing configurations were determined, including the slender body at wing's tip, which is the idea extracted from Dowell's work, so that the torsion and bending modes are coupled (torsional moment of inertia reduction). The aeroelastic model can be divided into two parts: First, the wings structural dynamic models are computed using the finite element method implements in NASTRAN solver. sequently, ZAERO software is employed to compute the aeroelastic model. Unsteady aerodynamic loading is computed through a lifting surface interference method known as ZONA 6. The wing models defined as test beds will be constructed and tested in different wind tunnels, including open and closed tests section types. The power spectral density approach might be employed as a way to identify flutter. The output signal from an accelerometer placed in the wing structure allows, through its power spectral density computation, the identification of flutter onset condition and the corresponding undisturbed flow speed. The PSD function increase means flow energy extraction, a condition to have flutter. Experimental flutter speeds are close to the theoretically computed ones by ZAERO. From these observations, it is possible to validate the aeroelastic theoretical model in a small disturbance context. After flutter onset , the limit cycle oscillations are observed, fed by freestream energy extraction. The aeroelastic models under investigation in this research are excellent models for nonlinear aeroelastic phenomena behavior study.
13
Rogers, Daniel R. "Design of a Three-Passage Low Reynolds Number Turbine Cascade with Periodic Flow Conditions". Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2684.pdf.
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Bin, Ab Wahab Abas. "The development of computer package for determining and solving pedestrian wind environmental discomfort and its wind tunnel validity test". Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305099.
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Taylor, Nigel John. "Adaptive wall technology for two-dimensional wind tunnel testing at high subsonic through to low supersonic speeds". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294622.
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Broughton, Cabot A. Carleton University Dissertation Engineering Aeronautical. "Experimental investigation of slotted wall wind tunnel test sections for low interference road vehicle testing". Ottawa, 1990.
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17
Sidelko, Stephanie. "Benchmark of aerodynamic cycling helmets using a refined wind tunnel test protocol for helmet drag research". Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40486.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (leaf 30).
The study of aerodynamics is very important in the world of cycling. Wind tunnel research is conducted on most of the equipment that is used by a rider and is a critical factor in the advancement of the sport. However, to date, a comprehensive study of time-trial helmets has not been performed. This thesis presents aerodynamic data for the most commonly used time-trial helmets in professional cycling. The helmets were tested at a sweep of yaw angles, from 0⁰ to 15⁰, in increments of 5⁰. The helmets were tested at three head angle positions at each yaw angle in order to best mimic actual riding conditions. A control road helmet was used to serve as a comparative tool. In order to maintain manufacturer confidentiality, the helmets were all randomly assigned variables. Thus, the thesis presents ranges of benefit and drag numbers, but does not rank by helmet name. The testing results showed that aerodynamic helmets offer drag reduction over a standard road helmet. The best and the worst performing helmets are all more aerodynamic than a road helmet.
by Stephanie Sidelko.
S.B.
18
Ehrmann, Robert S. "Development of Measurement Methods for Application to a Wind Tunnel Test of an Advanced Transport Model". DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/369.
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California Polytechnic State University, San Luis Obispo is currently working towards developing a Computational Fluid Dynamics (CFD) database for future code validation efforts. Cal Poly will complete a wind tunnel test on the Advanced Model for Extreme Lift and Improved Aeroacoustics (AMELIA) in the National Full-Scale Aerodynamics Complex (NFAC) 40 foot by 80 foot wind tunnel at NASA Ames Research Center in the summer of 2011. The development of two measurement techniques is discussed in this work, both with the objective of making measurements on AMELIA for CFD validation.
First, the work on the application of the Fringe-Imaging Skin Friction (FISF) technique to AMELIA is discussed. The FISF technique measures the skin friction magnitude and direction by applying oil droplets on a surface, exposing them to flow, measuring their thickness, and correlating their thickness to the local skin friction. The technique has the unique ability to obtain global skin friction measurements. A two foot, nickel plated, blended wing section test article has been manufactured specifically for FISF. The model is illuminated with mercury vapor lamps and imaged with a Canon 50D with a 546 nm bandpass filter. Various tests are applied to the wing in order to further characterize uncertainties related with the FISF technique. Human repeatability has uncertainties of ±2.3% of fringe spacing and ±2.0° in skin friction vector direction, while image post processing yields ±25% variation in skin friction coefficient. A method for measuring photogrammetry uncertainty is developed. The effect of filter variation and test repeatability was found to be negligible. A validation against a Preston tube was found to have 1.8% accuracy.
Second, the validation of a micro flow measurement device is investigated. Anemometers have always had limited capability in making near wall measurements, driving the design of new devices capable of measurements with increased wall proximity. Utilizing a thermocouple boundary layer rake, wall measurements within 0.0025 inches of the surface have been made. A Cross Correlation Rake (CCR) has the advantage of not requiring calibration but obtaining the same proximity and resolution as the thermocouple boundary layer rake. The flow device utilizes time of flight measurements computed via cross correlation to calculate wall velocity profiles. The CCR was designed to be applied to AMELIA to measure flow velocities above a flap in a transonic flow regime. The validation of the CCR was unsuccessful. Due to the fragile construction of the CCR, only one data point at 0.10589 inches from the surface was available for validation. The subsonic wind tunnel’s variable frequency drive generated noise which could not be filtered or shielded, requiring the use of a flow bench for validation testing. Since velocity measurements could not be made in the flow bench, a comparison of a fast and slow velocity was made. The CCR was not able to detect the difference between the two flow velocities. Currently, the CCR cannot be applied on AMELIA due to the unsuccessfully validation of the device.
19
Unal, Sadullah Utku. "Design, Construction And Preliminary Testin Of An Aeroservoelastic Test Apparatus To Be Used In Ankara Wind Tunnel". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607034/index.pdf.
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In this thesis, an aeroservoelastic test appratus is designed to investigate the flutter phenomena in a low speed wind tunnel environment. Flutter is an aeroelastic instability that may occur at control surfaces of aircrafts and missiles. Aerodynamic, elastic, and inertial forces are involved in flutter. A mathematical model using aeroelastic equations of motion is derived to investigate flutter and is used as a basis to design the test setup. Simulations using this mathematical model are performed and critical flutter velocities and frequencies are found. Stiffness characteristics of the test setup are determined using the results of these simulations. The test setup is a two degrees of freedom system, with motions in pitch and plunge, and is controlled by a servomotor in the pitch degree of freedom. A NACA 0012 airfoil is used as a control surface in the test setup. Using this setup, the flutter phenomena is generated in Ankara Wind Tunnel (AWT) and experiments are conducted to validate the results of the theoretical aeroelastic mathematical model calculations.
20
Szleper, Michele Lee. "Converging nozzle design for a subsonic wind tunnel to test heat sinks under impinging and parallel airflows". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17124.
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Yu, Kevin Xin Jun. "Investigation of Recessed and Concealed Sprinklers Activation in Wind Tunnel Plunge Test and in BRANZFIRE Computer Model". Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/1184.
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Installation of exposed fire sprinklers may cause inconvenience in areas where architectural and interior presentation is significant. In order to overcome this inconvenience, recessed and concealed sprinklers were created and are applied widely. Response Time Index (RTI) and C-factor are the thermal sensitivity (intrinsic parameters) used to characterise a sprinkler. They are also used as input parameters in computer fire models to simulate sprinkler response time. However, the RTI and C-factor are not published by the manufactures. Therefore the RTI and C-factor of the recessed and concealed sprinklers have been analysed and determined in this research. In order to obtain the RTI of the recessed and concealed sprinklers, four of the most commonly used sprinkler models (two recessed and two concealed) in New Zealand have been investigated in plunge test experiment by using a wind tunnel in this research. The UC3 wind tunnel used to conduct the plunge test has been fabricated in this research. This work has demonstrated that the UC3 wind tunnel could provide a very stable and uniform temperature profile in the test section. However, the velocity uniformity of the tunnel needs to be improved in the future. The "apparent" RTI for different recessed and concealed sprinkler models (two recessed and two concealed) have been determined in the plunge test experiment. It should be noted that the "final calculated RTI" for each tested recessed and concealed sprinklers has been denoted as "apparent RTI" in this study. BRANZFIRE computer model has been used to model the fire scenarios in the full scale fire tests conducted by Bill and Heskestad (1995). The best input fire object location, the best input sprinkler distance below the ceiling and the input "apparent C-factor" in BRANZFIRE for the flush, recessed, concealed and the recessed sidewall sprinklers have been determined in this research. This work has generally improved the guidance available to fire safety engineers for the RTI and C-factor of the recessed and concealed sprinklers.
22
Zientarski, Lauren Ann. "Wind Tunnel Testing of a Variable Camber Compliant Wing with a Unique Dual Load Cell Test Fixture". University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1448893315.
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McDonald, William J. "Design and computational analysis of aerodynamics in an annular cascade". Honors in the Major Thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1112.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering and Computer Science
Aerospace Engineering
24
Lines, Philipp A. "Upgrade of a LabVIEW based data acquisition system for wind tunnel test of a 1/10 scale OH-6A helicopter fuselage". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FLines.pdf.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, June 2003.Thesis advisor(s): E. Roberts Wood, Richard M. Howard. Includes bibliographical references (p. 53-54). Also available online.
25
Fisher, David T. "Wind tunnel performance comparative test results of a circular cylinder and 50% ellipse tailboom for circulation control antitorque applications". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283335.
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Brown, Kenneth Alexander. "A Study of Aerodynamics in Kevlar-Wall Test Sections". Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49383.
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This study is undertaken to characterize the aerodynamic behavior of Kevlar-wall test sections and specifically those containing two-dimensional, lifting models. The performance of the Kevlar-wall test section can be evaluated against the standard of the hard-wall test section, which in the case of the Stability Wind Tunnel (SWT) at Virginia Tech can be alternately installed or replaced by the Kevlar-wall test section. As a first step towards the evaluation of the Kevlar-wall test section aerodynamics, a validation of the hard-wall test section at the SWT is performed, in part by comparing data from NACA 0012 airfoil sections tested at the SWT with those tested at several other reliable facilities. The hard-wall test section showing good merit, back-to-back tests with three different airfoils are carried out in the SWT's hard-wall and Kevlar-wall test sections. Kevlar-wall data is corrected for wall interference with a panel method simulation that simulates the unique boundary conditions of Kevlar-wall test sections including the Kevlar porosity, wall deflection, and presence of the anechoic chambers on either side of the walls. Novel measurements of the boundary conditions are made during the Kevlar-wall tests to validate the panel method simulation. Finally, sensitivity studies on the input parameters of the panel method simulation are conducted. The work included in this study encompasses a wide range of issues related to Kevlar-wall as well as hard-wall tunnels and brings to light many details of the performance of such test sections.Master of Science
27
Chen, Ru-Ching. "Development of a Supersonic Nozzle and Test Section for use with a Magnetic Suspension System for Re-Entry Aeroshell Models". Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1544179612537658.
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Dwyer, William P. (William Patrick). "Measurement of flow boundary condition data and wing pressures in a wind tunnel test of a 45 deg swept wing". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/42182.
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Schouten, Shane Michael. "Complete CFD analysis of a Velocity XL-5 RG with flight-test verification". Texas A&M University, 2008. http://hdl.handle.net/1969.1/85894.
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The Texas A&M Flight Research Laboratory (FRL) recently received delivery of its
newest aircraft, the Velocity XL-5 RG. The Velocity can fly faster than the other aircraft
owned by the FRL and does not have a propeller in the front of the aircraft to disrupt the
air flow. These are definite advantages that make the Velocity an attractive addition to
the FRL inventory to be used in boundary-layer stability and transition control. Possible
mounting locations built into the aircraft for future projects include hard points in the
wings and roof of the fuselage. One of the drawbacks of the aircraft is that it has a
canard ahead of the main wing that could disrupt the incoming flow for a wing glove or
research requiring test pieces mounted to the hard point in the wing. Therefore, it is
necessary to understand the influence the canard and the impact of its wake on the wing
of the aircraft before any in-depth aerodynamic research could be completed on the
aircraft.
A combination of in-flight measurements of the canard wake and Computational
Fluid Dynamics (CFD) were used to provide a clear picture of the flowfield around the
aircraft. The first step of the project consisted of making a 3-D CAD model of the
aircraft. This model was then used for the CFD simulations in Fluent. 2-D, 3-D, inviscid,
and viscous simulations were preformed on the aircraft. A pressure rake was designed to
house a 5-hole probe and 18 Pitot probes that extended forward of the main wing to
measure the location and strength of the canard wake at various flight conditions. There
were five primary test points that were recorded at multiple times over the course of three flights. Once all of the data were collected from the flights, the freestream
conditions became the inputs into the final, 3-D CFD simulations on the aircraft.
The good agreement between the CFD results and the in-flight measurements
provided the necessary verification of the CFD model of the aircraft. These results can
be used in the future planning and execution of experiments involving the Velocity XL-5
RG.
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Scharnberg, Fábio Augusto. "Caracterização aerodinâmcia de edifícios através do espectro das cargas totais medidas em túnel de vento". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/181819.
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Nos últimos anos cresceu o interesse por construir edifícios cada vez mais altos, os quais estampam o poderio tecnológico e econômico das nações. Concomitantemente as estruturas se tornaram mais esbeltas e flexíveis e os fenômenos dinâmicos oriundos da ação do vento, que em edificações baixas não representam grande relevância no carregamento, começam a surgir e apresentar seus efeitos. Desta maneira, é importante conhecer como se desenvolve o escoamento do ar e a distribuição das pressões no entorno destas estruturas. Neste trabalho, caracteriza-se aerodinamicamente, através de dados oriundos de ensaios em túnel de vento, dois empreendimentos reais e presentes na engenharia nacional. Os carregamentos foram gerados através da integração simultânea de pressões e transformados em espectros de força, os quais auxiliam na visualização da energia cinética contida nas rajadas, na ocorrência de desprendimento cadenciado de vórtices, martelamento e na influência que as edificações vizinhas apresentam no escoamento. A análise é realizada local e globalmente, possibilitando verificar em que “zona”, ou faixa de altura, é mais significante para o carregamento da estrutura como um todo. O fenômeno de desprendimento de vórtices é caracterizado por um pico no espectro transversal à incidência do vento. Quando existem edificações ou obstáculos na região a barlavento, a estrutura pode ser martelada até a altura média destes obstáculos. Por fim, os resultados aqui apresentados podem servir de auxílio no pré-dimensionamento de estruturas com configurações similares, como comparativo e validação para pesquisas futuras e como referencial na elaboração de códigos normativos referentes ao tema. Destaca-se a importância de ensaios em túnel de vento, principalmente quando a estrutura a ser analisada possui um detalhamento arquitetônico complexo. Estes ensaios permitem ao projetista simular todos os casos de carregamento e os efeitos de vizinhança com maior confiabilidade e precisão em relação a métodos simplificados contidos, atualmente, em códigos e normas.In recent years many high-rise buildings have been built, which are a way to represent the economic and technological power of nations. Concomitantly, the structures have become slender and more flexible, and the dynamic phenomena of wind, which in low buildings do not represent a great relevance in the loading, start to show their effects. In this way, it is extremely important to know how the wind flow and the pressure distribution occur around these structures. In this research, two real projects, present in the national engineering, are characterized aerodynamically through data from wind tunnel tests. The loadings were processed through the simultaneous integration of pressures and transformed into force spectra, which aid in the visualization of the kinetic energy contained in the bursts, in the occurrence of vortex shedding, buffeting and the influence of the neighboring buildings on the wind flow. The analysis is performed locally and globally, making it possible to verify which "zone", or height range, is more significant to the loading of the structure as a whole. It can be seen that the phenomenon of vortex shedding is characterized by a peak in the crosswind spectrum and the buffeting phenomenon appears when there are buildings or obstacles in the windward region. Finally, the results presented here can be helpful in the pre-design of structures with similar configurations, in the comparison and validation for future researches and as a reference in the review of normative codes. Emphasis is given to the importance of wind tunnel testing, which allows the designer to simulate all loading cases and neighborhood effects with greater precision compared to simplified methods currently contained in codes and standards.
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Heim, Eugene Henry DeWendt. "Development of Methods for Improved Data Integrity and Efficient Testing of Wind Tunnel Models for Dynamic Test Conditions in Unsteady and Nonlinear Flight Regimes". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31050.
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Todayâ s high performance aircraft are operating in expanded flight envelopes, often maneuvering at high angular rates at high angles-of-attack, even above maximum lift. Current aerodynamic models are inadequate in predicting flight characteristics in the expanded envelope, such as rapid aircraft departures and other unusual motions. Unsteady flows of aircraft are of real concern. The ability to accurately measure aerodynamic loads directly impacts the ability to accurately model and predict flight. Current wind tunnel testing techniques do not adequately address the data fidelity of a test point under the influence of fluctuating loads and moments. Additionally, forced oscillation test techniques, one of the primary tools used to develop dynamic models, do not currently provide estimates of the uncertainty of the results during an oscillation cycle. Further, in testing models across a range of flight conditions, there are frequently parts of the envelope which are well behaved and require few data points to arrive at a sound answer, and other parts of the envelope where the responses are much more active and require a large sample of data to arrive at an answer with statistical significance. Currently, test methods do not factor changes of flow physics into data acquisition schemes, so in many cases data are obtained over more iterations than required, or insufficient data may be obtained to determine a valid estimate. Methods of providing a measure of data integrity for static and forced oscillation test techniques are presented with examples. A method for optimizing required forced oscillation cycles based on decay of uncertainty gradients and balance tolerances is also presented.Master of Science
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CAPPANERA, GIANLUCA. "Analisi fluidodinamica ed acustica di appendici palari per turbina eolica di piccola taglia e studio preliminare di sistema di accumulo in aria compressa". Doctoral thesis, Università Politecnica delle Marche, 2020. http://hdl.handle.net/11566/274610.
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Lo sviluppo tecnologico nel settore delle fonti rinnovabili, in particolare quello eolico, ha portato negli ultimi anni ad una forte presenza di aerogeneratori di grande e piccola taglia nelle zone rurali. In tali contesti applicativi, la problematica del rumore emesso dalle pale in rotazione è tuttora oggetto della ricerca scientifica mondiale. D’altra parte, in un panorama di transizione verso un sistema elettrico evoluto diviene cruciale l’applicazione di sistemi di stoccaggio dell’energia, pertanto lo studio di tecniche di accumulo alternative alle batterie è di assoluto interesse scientifico ed industriale. Il lavoro di ricerca è volto allo studio di appendici aerodinamiche note come Trailing-Edge Serrations, atte alla riduzione del rumore prodotto dalle pale di turbine eoliche, e allo studio preliminare di un sistema di accumulo, entrambi in applicazione agli aerogeneratori di piccola taglia. La campagna sperimentale ha visto dapprima la caratterizzazione fluidodinamica delle appendici effettuata in galleria del vento con test di tipo globale e locale, mediante l’impiego di un modello di ala con profilo NACA 642 014A ad alte prestazioni. I risultati hanno permesso di valutare le diverse qualità aerodinamiche di un tratto di pala eolica dovute alla presenza delle appendici allo scopo di prevederne l’impatto sulla produzione elettrica. I test sono proseguiti con la caratterizzazione acustica delle stesse appendici applicate stavolta ad un modello di pala rotante, posto in camera semi-anecoica. Grazie ad un set-up di misura appositamente progettato e ad innovativi algoritmi di localizzazione acustica è stata analizzata l’impronta sonora del modello con e senza appendici, in termini di emissione complessiva e mappatura delle sorgenti sonore. Il tutto è stato corredato dallo studio di un sistema di accumulo energetico di tipo “CAES” (Compressed Air Energy Storage) di taglia ridotta per il supporto alla produzione da fonte mini-eolica in ambiti di fornitura elettrica in zone remote.Recently, the technology development in renewable energy sector, especially for wind energy, has brought a wide presence of large and small wind turbines in rural areas. For these applications, noise emitted from rotating blades is a hot topic in worldwide scientific research. On the other hand, in the sight of an evolved electric system the delivery of energy storage systems is crucial. Thus, the study of storage techniques alternative to batteries is of absolute scientific and industrial interest. The research work here presented is aimed at the study of aerodynamic appendages known as Trailing-Edge Serrations (TES) conceived for wind turbine blades noise mitigation and at the preliminary evaluation of an energy storage system, both applicable to small wind turbines. The experimental campaign has firstly seen the fluid-dynamic study of TES from global and local points of view by the use of a fixed wing model with high performance NACA 642 014A airfoil, placed in the wind tunnel. Results allowed the evaluation of different aerodynamic performance due to the presence of the appendages, in order to foresee them impact on power production. Secondly, experiments proceeded with the acoustic characterization of TES applied to a rotating blade model placed in the semi-anechoic chamber. By a special measurement setup and the use of most recent algorithms for sound source localization, the acoustic footprint of the model with and without TES has been analysed, resulting in global noise emission and noise source mapping. The whole has been accompanied by a study of a Compressed Air Energy Storage (CAES) system of small size designed to support small wind turbine power production for electric supply of remote areas.
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ORLANDO, ANDREA. "Full-scale monitoring of the wind-induced response of vertical slender structures, with fixed and rotating masses". Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1049839.
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Nowadays, structural monitoring is gaining more and more attention in the field of wind engineering. On the wake of these developments, the thesis develops and applies a comprehensive structural monitoring procedure tailored for the validation and investigation in full-scale of the wind-induced response of vertical slender structures, with fixed and rotating masses. All the main aspects of the monitoring practice are discussed, regarding the number, location and type of the sensors, the acquisition and the transmission of the full-scale data, as well as the management of the experimental database by following an encoded scheme. In addition, the thesis highlights a number of issues typical of the monitoring activity that are not addressed in literature, providing inspiration to solve them. The defined procedure finds application in two monitoring campaigns launched by the Wind Engineering group at the University of Genoa: one slender structure with fixed masses (a light tower) and one slender structure with rotating masses (a small vertical axis wind turbine). As regards the light tower, a reference calculation model of the wind-induced response of poles and towers is selected from literature and is validated in full-scale. The input parameters needed for the application of the model are identified from experimental surveys, intersecting wind tunnel tests and dynamic identification techniques. The results highlight the goodness of the selected model and the large uncertainties associated to the input parameters. As regards the wind turbine, the full-scale data are used to investigate the contribution of the rotating parts to the dynamic behavior. In addition, the fatigue damage of the supporting tower is calculated under stationary and non-stationary excitation due to wind, turbine rotation, emergency stop and start. The results highlight the importance of the detail modeling, the fundamental role played by the non-stationary conditions and the errors committed when using conventional models of the load.
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Perkins, Hugh Douglas. "Development and Demonstration of a Computational Tool for the Analysis of Particle Vitiation Effects in Hypersonic Propulsion Test Facilities". Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1227553721.
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Wang, Haoting. "Experimental and Modeling Study of the Thermal Management of Li-ion Battery Packs". Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/79660.
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This work reports the experimental and numerical study of the thermal management of Li-ion battery packs under the context of electric vehicle (EV) or hybrid EV (HEV) applications. Li-ion batteries have been extensively demonstrated as an important power source for EVs or HEVs. However, thermal management is a critical challenge for their widespread deployment, due to their highly dynamic operation and the wide range of environments under which they operate. To address these challenges, this work developed several experimental platforms to study adaptive thermal management strategies. Parallel to the experimental effort, multi-disciplinary models integrating heat transfer, fluid mechanics, and electro-thermal dynamics have been developed and validated, including detailed CFD models and lumped parameter models. The major contributions are twofold. First, this work developed actively controlled strategies and experimentally demonstrated their effectiveness on a practical sized battery pack and dynamic thermal loads. The results show that these strategies effectively reduced both the parasitic energy consumption and the temperature non-uniformity while maintaining the maximum temperature rise in the pack. Second, this work established a new two dimensional lumped parameter thermal model to overcome the limitations of existing thermal models and extend their applicable range. This new model provides accurate surface and core temperatures simulations comparable to detailed CFD models with a fraction of the computational cost.Ph. D.
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Kichkie, Nabil. "Comportement dynamique en lacet d'une eolienne a axe horizontal". Paris, ENSAM, 1987. http://www.theses.fr/1987ENAM0007.
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Determination de l'influence des parametres geometriques et aerodynamiques sur le comportement dynamique de la machine grace a la resolution du systeme d'equations differentielles qui caracterise le mouvement d'oscillation. Essais en soufflerie sur une maquette a l'echelle 1/3,5 permettant de determiner les couples de rappel ainsi que le coefficient de puissance et le comportement en lacet. Transposition des resultats de la maquette au prototype par l'application des lois de la similitude
37
Minair, Catherine. "Les angles privilégiés, grands invariants universaux : une approche par la dynamique des fluides, l'esthétique et la physio-biologie". Valenciennes, 1987. https://ged.uphf.fr/nuxeo/site/esupversions/a2fee09c-75f7-461c-88c5-71e89bf41c12.
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Des visualisations en soufflerie jusqu'à l'éclatement ont mis en évidence des relations de filiation entre les valeurs toujours privilégiées du système inter tourbillonnaire sur des ailes delta minces et les divers paramètres en particulier l'angle d'apex. L'universalité de la notion d'angle privilégié est soulignée par des considérations architecturales telles que le nombre d'or, et picturales en même temps que par des phénomènes biologiques confirmés par la géométrie, l'arithmétique et la psychophysiologie.
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Lemoult, Bernard. "Contribution a la connaissance des actions du vent sur les batiments a structure metallique". Poitiers, 1988. http://www.theses.fr/1988POIT2201.
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Etude experimentale a echelle reduite dans une soufflerie a couche limite (cstb, nantes), pour determiner le champ de pression; le role de la turbulence du vent amont sur les sollicitations extremes sur un batiment a ossature metallique est souligne
39
Di, Nicola Federico. "Energy harvesting from piezoelectric devices embedded in a 3D printed wing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9705/.
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This thesis work has been carried out at Clarkson University in Potsdam NY, USA and involved the design of a low elongation wing, consisting of parts made by polylactide (PLA) using the fused deposition model (FDM) technology of Rapid Prototyping, then assembled together in a thin aluminum spar. The aim of the research is to evaluate the feasibility of collecting electrical energy by converting mechanical energy from the vibration of the wing flutter. With this aim piezoelectric stripes were glued in the inner part of the wing, as well as on the aluminum spar, as monomorphic configuration.
During the phases of the project, particular attention was given to the geometry and the materials used, in order to trigger the flutter for low flow velocity.
The CAD software SolidWorks® was used for the design of the wing and then the drawings were sent to the Clarkson machine shop in order to to produce the parts required by the wing assembly.
FEM simulations were performed, using software MSC NASTRAN/PATRAN®, to evaluate the stiffness of the whole wing as well as the natural vibration modes of the structure. These data, in a first approximation, were used to predict the flutter speed.
Finally, experimental tests in the Clarkson wind tunnel facility were carried out in order to validate the results obtained from FEM analysis. The power collected by the piezoelectrics under flutter condition was addressed by tuning the resistors downstream the electronic circuit of the piezoelectrics.
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Tarbadar, Rima. "Étude expérimentale en vraie grandeur et modélisation des pressions induites par le vent dans les combles : application à l'étanchéité des toitures à l'eau". Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0414.
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La pénétration d'eau de pluie à travers une toiture à pentes constituée de petits éléments est principalement liée à la différence de pression externe et interne, générée par le vent sur le toit. Le champ de pression externe est accessible aux mesures, sur maquette en soufflerie atmosphérique. En revanche, le champ de pression interne ne peut pas être obtenue qu'en vraie grandeur. Une modélisation numérique de ce dernier a donc fait l'objet de cette thèse. Il s'agit plus précisement de calculer la pression instantanée en sous-face de la couverture, dotée ou non d'un écran qu'il soit souple ou rigide. L'estimation de la pression interne est délicate faute d'une bonne connaissance des caractéristiques de l'écoulement à travers des parois perméables. Une campagne de mesures en vraie grandeur a donc été menée pour caractériser la perméabilité à l'air de la toiture pour un revêtement donné (banc de mesures), ensuite pour étudier les effects de la vitesse et de la turbulence du vent et de l'intensité de la pluie sur cette perméabilité (soufflerie climatique). La pression interne issue du modèle sans écran reproduit bien celle mesurée. L'étude paramétrique du cas avec écran à montré la possibilité de réduire considérablement la pression différentielle. Une bonne connaissance des paramètres qui influencent le différentiel de pression permet de concevoir des toits à pentes, pour lesquels les problèmes de pénétration d'eau de pluie sont considérablement réduitsGenerally, the rain penetration through pitched lapped roofs is created by the difference of external and internal pressure, generated by the wind. In this thesis, a numerical model has been developped for prediction of internal pressure under the elements (the external pressure can be measured on a model in a boundary layer wind-tunnel). Two cases have been studied : roof without underlay, roof with flexible or stiff underlay. The dynamics of internal pressure is, in general, a complex problem. This is due to the poor knowledge on the leakage paths characteristics. Therefore, full-scale experimental studies have been carried out to characterize the roof wind permeability (test appartus) and to investigate the effects of windspeed, atmospheric turbulence and rain intensity on this permeability (climatic wind-tunnel). The analytical results were compared with full-scale results (roof without underlay case), and they matched closely. Parametric studies (underlay case) have shown that it is possible to reduce considerably the wind loads. Through a complete knowledge of the controlling parameters it will be possible to design and construct pitched lapped roofs, from which the problems of rain penetration is strongly reduced
41
Moses, Kenneth C. "A Durable Terrestrial Drive Train for a Small Air Vehicle". Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270233578.
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Thesis (Master of Sciences (Engineering))--Case Western Reserve University, 2010Department of EMC - Mechanical Engineering Title from PDF (viewed on 2010-05-25) Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
42
Bonnardel, Xavier-Henri. "Etude théorique et expérimentale d'interactions aérodynamiques : application à l'effet de sol et à l'interaction rotor arrière-dérivé d'un hélicoptère". Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22059.
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Ferret, Bernard. "Etude expérimentale de l'intéraction entre un tourbillon isolé et un profil d'aile". Poitiers, 1988. http://www.theses.fr/1988POIT2317.
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En soufflerie subsonique, on genere un tourbillon a partir du decrochage dynamique d'un volet mis rapidement en incidence par commande numerique. Ce tourbillon unique et reproductible se detache et est convecte par l'ecoulement sur un profil naca0012. Cette maquette, montee sur une balance de portance et de trainee instationnaires est munie de prises de pression multiplexees sur un capteur par un commutateur pneumatique
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Journe, Paul. "Anémomètre ultrasonore corrélatif". Grenoble 1, 1989. http://www.theses.fr/1989GRE10128.
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Cette these retrace les etapes rencontrees lors du projet de recherche et developpement: mise au point d'un anemometre ultrasonore correlatif. Dans la premiere moitie du rapport sont presentes differents elements devant permettre de poser rigoureusement et precisemment le probleme: caracterisation d'un appareil repondant a un ensemble de besoins et de contraintes. Dans la deuxieme moitie du rapport sont presentees les experimentations et les etudes necessaires a la mise au point d'un anemometre prototype. Ces experiences sont relatives a la faisabilite de l'appareil aux methodes de traitement de l'information (correlation, statistiques, redondance), et aux problemes technologiques rencontres (lies surtout a l'utilisation des ultrasons dans l'air). Enfin, les resultats de tests de validation en soufflerie sont exposes
45
Fletcher, Nathan James. "Design and Implementation of Periodic Unsteadiness Generator for Turbine Secondary Flow Studies". Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1560810428267352.
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Brožek, Petr. "Návrh zařízení pro měření aerodynamických sil a momentů v aerodynamickém tunelu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231647.
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The masters thesis is focused on design of the device for measurement of the aerodynamic forces and moments acting on radiators mounted in the wind tunnel test section. The thesis also includes the analysis of the aerodynamic drag which is produced by radiators and the LabView application software development.
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Zedník, Roman. "Příprava experimentálního měření aerodynamických charakteristik na zmenšeném modelu automobilu v aerodynamickém tunelu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417795.
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This master thesis focuses on designing of an external six-component balance. This universal concept would provide access of results from different models of wings, aircraft and automobiles with relatively small scales. This work also includes theoretical background needed in aerodynamic testing, analysis of 1D beam element model of scale and explanation of components used in scale. Lastly methods of calibration and measurement in aerodynamic tunnel are described, which can be adopted for this design to achieve the adequate level of accuracy.
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Sanchez, Marc. "Etude des extracteurs d'air hybrides éoliens : conception de géométries et analyse des écoulements". Thesis, Perpignan, 2015. http://www.theses.fr/2015PERP0040/document.
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Ce travail de thèse concerne l'étude d'extracteurs d'air hybrides éoliens. Il se décompose en des investigations amont et appliquées. Dans la partie amont, des simulations fines ont été effectuées en conduite carrée avec et sans rotation, pour des nombres de Reynolds turbulents de l'ordre de 600, afin d'analyser l'impact de la rotation sur la turbulence. Elles ont montré que la rotation rompt la symétrie de l'écoulement. La partie appliquée est dédiée à la conception d'une nouvelle géométrie d'extracteur d'air. Cette géométrie a été proposée à partir de l'analyse de simulations RANS. Ses performances ont été confirmées par des mesures expérimentales sur banc d'essais. Les tests en soufflerie d'un système de captage d'énergie éolienne, conçu pour l'extracteur, ont mis en évidence son adéquation au régime de fonctionnement de l'extracteur. Les essais expérimentaux de l'extracteur complet, montrent que le système de captage apporte une part significative de l'énergie. Des essais en soufflerie ont permis d'observer le comportement global de l'extracteurThis PhD work concerns the study of hybrid air extractors. It is composed of upstream and applied investigations. In the upstream part, fine simulations are realized in square duct flow with and without rotation to analyse the impact of rotation on turbulence. It is found that rotation removes symmetry property of the flow with turbulent Reynolds number of 600. The applied part is dedicated to the conception of a new air extractor geometry. This geometry is proposed from the analyse of RANS simulations. Its performances are confirmed by experimental measurements on test rig. Wind tunnel tests of a wind power capturing system, designed for the extractor, show a good adequation to the operating regime of the extractor. Experimental investigations on the complete air extractor, show the wind power capturing system brings a significant part of the energy. Wind tunnel tests allow to observe the complete air extractor behaviour
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Harion, Jean-Luc. "Influence de différences de densité importantes sur les propriétés de transfert d'une couche limite turbulente". Grenoble INPG, 1994. http://www.theses.fr/1994INPG0133.
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Les effets de differences de densite importantes sur les transferts turbulents en couche limite sont etudies experimentalement. L'installation principale est une soufflerie pressurisable. Les ecarts de densite au sein de la couche limite sont produits par injection tangentielle d'air ou d'helium dans un melange de ces deux constituants. Les mesures thermo-anemometriques portent sur les concentrations, vitesses et frottement parietal (valeurs moyennes, fluctuations) en aval de l'injection. Une sonde d'interference (fil+film) a ete mise au point avec de nouvelles conditions de surchauffes permettant l'acces a une gamme de vitesses plus etendues que les utilisations anterieures. Une sonde double ainsi qu'une nouvelle sonde aspirante parietales ont egalement ete developpees. Leur comportement physique a ete analyse. Les resultats montrent que pour un gaz donne, le developpement du jet parietal est principalement gouverne par le rapport des vitesses externe et d'injection. Pour des gaz differents, un bon regroupement des resultats est opere en tenant compte du nombre de reynolds d'injection et d'un terme base sur le rapport des densites. La couche limite turbulente obtenue est associee a un gradient de densite normal a la paroi. A vitesse d'injection donnee, les mesures mettent en evidence la conservation du frottement, et donc l'influence des differences de densite sur la vitesse de frottement. De plus, une forte correlation entre les variations de densite et de vitesse montrent l'influence marquee des structures coherentes sur les phenomenes de transfert
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Villafañe, Roca Laura. "Experimental Aerothermal Performance of Turbofan Bypass Flow Heat Exchangers". Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/34774.
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The path to future aero-engines with more efficient engine architectures requires advanced
thermal management technologies to handle the demand of refrigeration and lubrication. Oil
systems, holding a double function as lubricant and coolant circuits, require supplemental
cooling sources to the conventional fuel based cooling systems as the current oil thermal
capacity becomes saturated with future engine developments. The present research focuses on
air/oil coolers, which geometrical characteristics and location are designed to minimize
aerodynamic effects while maximizing the thermal exchange. The heat exchangers composed
of parallel fins are integrated at the inner wall of the secondary duct of a turbofan. The
analysis of the interaction between the three-dimensional high velocity bypass flow and the
heat exchangers is essential to evaluate and optimize the aero-thermodynamic performances,
and to provide data for engine modeling. The objectives of this research are the development
of engine testing methods alternative to flight testing, and the characterization of the
aerothermal behavior of different finned heat exchanger configurations.
A new blow-down wind tunnel test facility was specifically designed to replicate the engine
bypass flow in the region of the splitter. The annular sector type test section consists on a
complex 3D geometry, as a result of three dimensional numerical flow simulations. The flow
evolves over the splitter duplicated at real scale, guided by helicoidally shaped lateral walls.
The development of measurement techniques for the present application involved the design
of instrumentation, testing procedures and data reduction methods. Detailed studies were
focused on multi-hole and fine wire thermocouple probes.
Two types of test campaigns were performed dedicated to: flow measurements along the test
section for different test configurations, i.e. in the absence of heat exchangers and in the
presence of different heat exchanger geometries, and heat transfer measurements on the heat
exchanger. As a result contours of flow velocity, angular distributions, total and static
pressures, temperatures and turbulence intensities, at different bypass duct axial positions, as
well as wall pressures along the test section, were obtained. The analysis of the flow
development along the test section allowed the understanding of the different flow behaviors
for each test configuration. Comparison of flow variables at each measurement plane
permitted quantifying and contrasting the different flow disturbances. Detailed analyses of the
flow downstream of the heat exchangers were assessed to characterize the flow in the fins¿
wake region. The aerodynamic performance of each heat exchanger configuration was
evaluated in terms of non dimensional pressure losses. Fins convective heat transfer
characteristics were derived from the infrared fin surface temperature measurements through a
new methodology based on inverse heat transfer methods coupled with conductive heat flux
models. The experimental characterization permitted to evaluate the cooling capacity of the
investigated type of heat exchangers for the design operational conditions. Finally, the
thermal efficiency of the heat exchanger at different points of the flight envelope during a
typical commercial mission was estimated by extrapolating the convective properties of the
flow to flight conditions.Villafañe Roca, L. (2013). Experimental Aerothermal Performance of Turbofan Bypass Flow Heat Exchangers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34774
TESIS