The dynamics of the unstart process in inlet / isolator models mounted to the floor of a Mach 5 wind tunnel are investigated experimentally. The most extensively studied model has an inlet section that contains a 6-degree compression ramp and the isolator is a rectangular straight duct that is 25.4 mm high by 50.8 mm wide by 242.3 mm long. Unstart is initiated by raising a motor-driven flap that is located at the downstream end of the isolator section. Unstart proceeds with the formation of a shock system that propagates upstream at an average velocity of about 37 m/s (in the lab frame of reference), which is five percent of the freestream velocity. Unstart is seen to be associated with strong shock-induced separation that leads to reverse flow velocities up to about 300 m/s as measured by PIV. Both the schlieren imaging and PIV data suggest the dynamics and flow structure of the unstart process are dependent on inlet geometry. Furthermore, the PIV data indicate the unstart process to be highly three-dimensional. Finally, tripping the ceiling and sidewall boundary layers was seen to result in slower unstart processes. In addition, results are presented for 0-degree (no inlet) and 8-degree inlet / isolator models. In the 0-degree model, the experimental data show that the flow structure and propagation velocities of the unstart shock system are much more constant than those measured in unstart events with an inlet. In addition, an increased inlet compression angle appears to result in an increased unstart propagation velocity in the isolator. This is possibly related to the fact that with an increased compression ramp angle, the unstart shock system propagates against a lower momentum opposing flow. Furthermore, the inlet geometry is also seen to affect the flow that follows the unstart process. Experiments were also conducted with each of the three inlets attached to a shortened isolator. The short-isolator experiments showed it was possible to form a stable high-compression shock system in the isolator by raising the flap. This was not the case in longer isolator tests. / text

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A key remaining challenge in the design of hypersonic vehicles is the incomplete understanding of the process of boundary-layer transition. Turbulent heating rates are substantially higher than those for a laminar boundary layer, and large uncertainties in transition prediction therefore demand conservative, inefficient designs for thermal protection systems. It is only through close collaboration between theory, experiment, and computation that the state of the art can be advanced, but experiments relevant to flight require ground-test facilities with very low disturbance levels. To enable this work, a unique Mach 6 low-disturbance wind tunnel, previously of NASA Langley Research Center, is established within a new pressure-vacuum blow-down infrastructure at Texas A&M. A 40-second run time at constant conditions enables detailed measurements for comparison with computation. The freestream environment is extensively characterized, with a large region of low-disturbance flow found to be reliably present for unit Reynolds numbers Re < 11×10^6 m-1. Experiments are performed on a 5º half-angle flared cone model at Re = 10×10^6 m-1 and zero angle of attack. For the study of the second-mode instability, well-resolved boundary-layer profiles of mean and fluctuating mass flux are acquired at several axial locations using hot-wire probes with a bandwidth of 330 kHz. The second mode instability is observed to undergo significant growth between 250 and 310 kHz. Mode shapes of the disturbance agree well with those predicted from linear parabolized stability equation (LPSE) computations. A 17% (40 kHz) disagreement is observed in the frequency for most-amplified growth between experiment and LPSE. Possible sources of the disagreement are discussed, and the effect of small misalignments of the model is quantified experimentally. A focused schlieren deflectometer with high bandwidth (1 MHz) and high signal-to-noise ratio is employed to complement the hot-wire work. The second-mode fundamental at 250 kHz is observed, as well as additional harmonic content not discernible in the hot-wire measurements at two and three times the fundamental. A bispectral analysis shows that after sufficient amplification of the second mode, several nonlinear mechanisms become significant, including ones involving the third harmonic, which have not hitherto been reported in the literature.

Magistro darbe nagrinėjamas mokomasis aerodinaminis vamzdis, su kuriuo bus galima atlikti laboratorinius darbus ir nesudėtingus mokslinius tyrimus. Aptariama aerodinaminio vamzdžio reikšmė studentams, Lietuvos ūkiui ir aplinkosaugai. Taip pat pateikiama, kokius bandymus su aerodinaminiu vamzdžiu bus galima atlikti Pastatų energetikos katedroje. Apžvelgti laboratorijos įrangos gamintojų – Aerolab, G.u.n.t, Armfield, Stirolab, GDJ Inc mokomieji aerodinaminiai vamzdžiai, projektavimo rekomendacijos. Pastatų energetikos katedrai suprojektuotas aerodinaminis vamzdis, papildomai pridėti triukšmo slopintuvai prieš ir už ventiliatoriaus. Taip pat atlikta kompiuterinių programų, kuriomis naudojantis galima atlikti oro srautų moduliaciją, analizė, ir pasirinkus tinkamiausią programą atlikta Pastatų energetikos katedros aerodinaminio vamzdžio darbinės kameros moduliacija. Šio baigiamojo darbo rezultatas – pagamintas ir surinktas mokomasis aerodinaminis vamzdis, kuris bus naudojamas laboratoriniams darbams ir tyrimams atlikti. Darbą sudaro 11 dalys: įvadas, 11 skyrių dėstomoji dalis, išvados, literatūros sąrašas. Darbo apimtis – 65 p. teksto be priedų, 39 iliustr., 9 lent., 30 bibliografiniai šaltiniai. Atskirai pridedami darbo grafikai ir priedai. / Masters‘ thesis deals with an educational wind tunnel which is to be used to carry out laboratory works and simple research. It disscuses the importance of wind tunnel for students, Lithuanian economy and environment protection. It also presented tests those can be made with wind tunnel in the department of buildings’ energetics. The educational wind tunnels, design recommendations of the laboratory equipment manufacturer – Aerolab, G.u.n.t, Armfield, Stirolab, GDJ Inc were overviewed. Wind tunnel for department of buildings’ energetics was designed, in addition silencers before and behind the fan were added. There are also made an analysis of computer programs, which enable air flow modulation, and selecting the best program the wind tunnel working chamber modulation of the department of buildings’ energetics was performed. The result of the thesis – produced and assembled educational wind tunnel, which will be used for laboratory work and research. The work consists of eleven parts: introduction, describtion, conclusions, references. Work size – 65 pages without appendixes, 39 figures, 9 tables, 30 references. Appendixes.

Alleviating loads on a wind turbine blades would allow a reduction in weight, and potentially increase the size and lifespan of rotors. Trailing edge flaps are one technology proposed for changing the aerodynamic characteristics of a blade in order to limit the transformation of freestream wind fluctuations into load fluctuations within the blade structure. An instrumented wind turbine test rig and rotor were developed to enable a wide-range of experimental set-ups for such investigations. The capability of the developed system was demonstrated through a study of the effect of stationary trailing edge flaps on blade load and performance. The investigation focused on measuring the changes in flapwise bending moment and power production for various trailing edge flap parameters. The blade was designed to allow accurate instrumentation and customizable settings, with a design point within the range of wind velocities in a large open jet test facility. The wind facility was an open circuit wind tunnel with a maximum velocity of 11m/s in the test area. The load changes within the blade structure for different wind speeds were measured using strain gauges as a function of flap length, location and deflection angle. The blade was based on the S833 airfoil and is 1.7 meters long, had a constant 178mm chord and a 6o pitch. The aerodynamic parts were 3D printed using plastic PC-ABS material. The total loading on the blade showed higher reduction when the flap was placed further away from the hub and when the flap angle (pitching towards suction side) was higher. The relationship between the load reduction and deflection angle was roughly linear as expected from theory. The effect on moment was greater than power production with a reduction in moment up to 30% for the maximum deflection angle compared to 6.5% reduction in power for the same angle. Overall, the experimental setup proved to be effective in measuring small changes in flapwise bending moment within the wind turbine blade.

Ankara Wind Tunnel (AWT) operated by T&Uuml / BiTAK-SAGE is the only big sized wind tunnel in Turkey. The AWT was constructed in late 1940&rsquo / s but was not operated until 1993 when the tunnel was turned over T&Uuml / BiTAK-SAGE. Since 1993, a series of modernization work has been undergoing in order to match the demands of the 21st century. In wind tunnels, models are positioned by special mechanisms that are instrumented to get the test data specific to the test performed. Models are assembled from their rear sides on these mechanisms called model support systems in order not to influence the flow around them. In this thesis, a conceptual design of a 6 degrees-of-freedom model support system for AWT is accomplished. A detailed system model is developed for the controller design. A force controller to perform store separation tests in real time is designed, tuned, and validated with computer simulations.

The technology of UAV (Unmanned Aerial Vehicle) has developed since its conception many years ago. UAVs have several features such as, computerised and autonomous control without the need for an on-board pilot. Therefore, there is no risk of loss of life and they are easier to maintain than manned aircraft. In addition, UAVs have an extended range/endurance capability, sometimes for several days. This makes UAVs attractive for missions that are typically

Thesis (M. Eng.)--Carleton University, 1993. / Also available in electronic format on the Internet.

The Fan Assessment Numeration System (FANS) is an improved air velocity traverse method for measuring in situ fan performance. The FANS has been widely used, but variations of its test procedure are commonly employed to accommodate physical or operational barriers encountered in the field. This laboratory study evaluated the use of transitions to connect a 1.37m FANS unit to two smaller fans (1.22m and 0.91m diameter) and one 1.37m diameter fan. Tests were conducted with the FANS unit positioned on both intake and discharge sides of the fans. Three different transition angles (30o, 45o and 60o) and the use of no transition were evaluated. Discharge tests were also performed with no enclosed connection between FANS and fan housings. A different experiment was conducted for each fan size. Data was analyzed by comparing test results to the control with Dunnett’s procedure. Results showed significant differences as much as 5.3% ± 1.20% for intake treatments, 17.2% ± 3.04% for sealed discharge treatments and 37.1% ± 12.24% for discharge treatments with no enclosed connection. All transition angles produced similar fan test results. Differences between test results from the discharge and control treatments increased as differences between FANS and fan dimensions increased.

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.