Low speed wind tunnel testing alan pope free download

Policy barriers for dairy value chain development in Bangladesh with a focus on the Northwest region. The book is organized for quick access to topics of interest, and examines basic test techniques and objectives of modeling and testing aircraft designs in low-speed wind tunnels, as well as applications to fluid motion analysis, automobiles, marine vessels, buildings, bridges, and other structures subject to wind by: The original is the one book everyone in the wind tunnel test area had open on their desk.

It covered everything from overall theory of aerodynamic testing to details of wind tunnel design. The revision brings it up to date with use of computers and digital test gear. I do recommend this book. The original is the one book everyone in the wind tunnel test area had open on their desk.

Low-Speed Wind Tunnel Testing book. The book is organized for quick access to topics of interest, and examines basic test techniques and objectives of modeling and testing aircraft designs in low-speed wind tunnels, as well as applications to fluid motion analysis, automobiles, marine vessels, buildings, bridges, and other structures subject to wind.

The fourth edition of a classic text reference, this book is unique in covering all aspects of low-speed wind tunnel design, analysis, testing, and instrumentation. They are typically very heavily scheduled for their environmental purposes. The size that 1. Firebladed Fan 2. Motor 3.

MotorGenerator Set 4. Equipment Room 5. Refrigeration Unit 6. Courtyard Cooling Tower 7. Ford Motor Co. Dearborn, Michigan. Steam Lances 9. Sun Lamps Test Section Control Room Movable Corner Turning Vane And the flow quality is generally less than is thought proper for external aerodynamic studies. Most automobiles are considered to be aerodynamically bluff bodies, which reflects the fact that there are almost always significant regions of separated flow on an automobile.

This leads to interactions between the flow about the model and the wind tunnel walls or free jet boundary that are somewhat more complex than is the case for bodies with fully attached flow.

One result is that understanding these types of flow in wind tunnels continues to engage research personnel. A major point concerning wind tunnel experiments on automobiles is thequestion of ground simulation.

To provide astrict simulation, the wind tunnel floor must move withthespeed of theair. A considerable amount of work hasbeen carried out toaddress thequestion of when this isnece sary andwhen thiscondition canberelaxed. Generally speaking, it is thecurrent practice tousea fixed floor with some treatment toproduce athin boundary layer for production car experiments and a moving floor for formula J or Championship Auto Racing Team CART race car experiments.

The principal difference is the clearance between the bottom of the car and the ground. This and other issues will beaddressed inmore detail later in the book. Wind tunnels for automotive experiments are increasingly required to have low-flow noise levels so that wind noise associated with flow around the vehicle can be measured with sufficient accuracy to allow assessment of proposed design variations. Realizing the advantages of holding the model and themeasuring instrumentation still and letting the fluid move, as well as the enormous cost of running full-scale experiments, and that noise suppression is more easily handled with air than with water, the David Taylor Research Center designed and built a unique wind tunnel known as the Anechoic Flow Facility.

While basically a single- return wind tunnel with a closed test section upstream of an open one, its other features both as a wind tunnel and low-noise facility have made an enormous contribution to the world of wind tunnels for others to copy. A sketch of the tunnel is shown in Figure 2. Special features include: 1. The use of a wide-angle diffuser to permit a contraction ratio of IO: 1with- out a long diffuser and return path with corresponding high constructions costs.

The use of two turns and two 80 turns instead of the more customary four 90 turns. This permitted the length needed for the fan noise suppressors, again with a shortened passage. Extremely heavy concrete constructions plus the use of noise suppression materials on walls, ceilings, and turning vanes.

An anechoic chamber surrounding the open test section to yield by far the lowest noise levels achieved in a wind tunnel. Section isolation is practiced throughout, as well as isolation of the entire tunnel from the ground through several feet of crushed rock. The wedges used for reflection cancellation are evident in the background.

Many general-purpose wind runnels have been modified to include noise absorp- tion materials and other features to provide quieter environments in which some 8eroacoustic work can becarried OUL Increased understanding of aeroacoustic princi- ples, better material availability, and improved instrumentation that allows useful measurements in the presence of higher background noise have come together with increasing demands of users for quieter vehicles to stimulate an increasing level of ICtivity inaeroacoustic studies inboth special- andgeneral-purpose wind tunnels.

An - of ageneral-purpose facility that has received extensive acoustic treatment is National Full Scale Facility. However, water tunnels are used in essentially the same way and under the same physical principles as low-speed wind tunnels. Water tunnels support direct investigation of cavitation phenomena that cannot be done in a wind tunnel.

Water tunnels tend to be physically smaller than wind tunnels for achieving the same Reynolds numbers. However, this apparent advantage is more than offset by the greater difficulty in having water as theworking fluid instead of air. There are few "large" water tunnels. There is a in. This tunnel is used for underwater vehicle development. Small water tunnels have been widely used for flow visualization studies.

It has been possible to achieve low dispersion of die streaks, which combined with very low flow speeds has aUowed more detailed observation and associated photographic and video recording than has been achieved in wind tunnels. The most common of these is the 7 X l't class wind tunnel that have those approximate dimensions or their test sections. Air Force has one.

Navy has two, five universities in the United States have tunnels of this class, and numerous other agencies and companies throughout the world have or had tunnels of this class. Many of these tunnels have been closed and some have been destroyed as work that had its origin in these tunnels moved more specialized facilities spawned by increasing understanding of particular problems. Its layout is shown in Figure 2. These facilities continue to be very good for a wide range of vehicle-related experiments and continue to be the best available for a range of special-purpose experiments that have nOI spawned their own specially designed aerodynamic facili- ties.

For many purposes tbey are simply the most cost effective at carrying out exploratory investigations when no fully satisfactory capability is available. Aselection of subjects of aerodynamic experiments not previously mentioned is added bere to further emphasize the broad range of applications that arise for low- speed wind tunnels.

People Attention has been paid to people-drag of tbe type encountered by bike racers and skiers. The bicycles should ideally be arranged so that the biker can pedal and with " Martin wind tunnel at the University of Maryland. Experiments have shown a change of drag with the number of wheel spokes and other details. Wind tunnel entries have proven beneficial for showing bike riders their lowest drag posture. For skiers, the "model" is mounted in the tunnel and during a run at approximately 55 mph which is close to full-scale "flight" assumes a series of positions endeavoring to learn which minimizes his or her drag or possibly the lift- to-drag ratio in the case of ski jumpers.

The fascinating part of these experiments, and they are not without hilarity despite the seriousness of the end results, is that the model corrects his or her own drag by watching a drag indicator. Position changes are shown on frontal and side TV projectors, and coaching suggestions sent in as needed.

A programmed computation in real time can also be presented so the skier or biker can be shown how much each change helps in terms of race time or distance results. Substantial improvements in clothing have resulted from such programs. Insome cases clothing has been evaluated to seek increases in drag when it is to beworn by an athlete seeking to increase load during training. Airborne troops have been trained in vertical wind tunnels so that they are familiar with the condition they will experience when jumping from aircraft.

Birds and Insects Over the years a number of wind tunnel experiments have been made of natural fliers, alive, frozen, and simulated. Initially experimenters were seeking mysterious and incredibly efficient devices that nature's creatures were supposed to have. No such things have been found; nor are they needed to explain natural flight.

The high landing angles of some birds have been duplicated with highly latticed wings, and bird power has been estimated to be in line with demonstrated performance. Bird fat turns out to have a similar energy content to jet fuel. Differences tbat remain are of small magnitude and are within the uncertainty of experiments to date.

Live insects have been somewhat more cooperative than live birds and have flown more extensively in tunnels for close observation. In some cases, tunnels similar in concept to the "stability" tunnels described above have been used. Wind Power Devices Currently, and for the foreseeable future, there is a lot of interest in developing devices that will supply direct energy for pumping water for irrigation, to prevent pond freezing, or for the generation of electricity.

Experiments are usually run at low tunnel speeds, but the tunnel engineer should satisfy himself or herself of the model integrity and that it has a brake and that damage to the tunnel is not likely to occur.

Experiments will probably encompass runs under various power loadings and at different Reynolds numbers. It would be preferable to evaluate windmills in the wind gradient that they will eventually see, but this is rarely done. The tunnel engineer should encourage the windmill promoter to have siting experiments made inan environmental wind tunnel to get the best results in the field.

Courtesy Vcrdian-Calspan Operations. A long-term record cannot be established for the. For estimating the maximum coefficient one should use, respectively, 0. The lower maximum coefficient for the Savonius type is offset in practice by its lower manufactur- cost Measurement of side force is not normally made but should be, as all develop small to substantial lateral "lift"force, as does an airplane propeller.

L arge installations seem to suffer from making a disturbing buzzing sound, interrupting TV reception, and having instabilities. Windmills should never be put on a rooftop, even to get a high local velocity. Natural winds have many times the total power needed for the entire electrical needs of humans, but the energy is very diffuse and therefore requires considerable ingenuity to harness economically.

Windmills have, however, been a source of power that has been used successfully in certain locales for hundreds of years. It turns out that a maximum of Solar Collectors Interest in solar energy has spawned a need for wind loads and moments on the various solar collectors. Since winds come from all directions. I nparticular, there is interest in drag also caJ J ed lateral load and pitching moment and with the loads along the long axis.

Yawing moments and roll moments are measured but are usually of lesser import. Besides needing loads for strength and preservation of the proper focal distance, the pitching moment is needed to size the drive motor that keeps the collector aimed at the sun and turns it over at night or in bail to reduce damage to the ret1ecting surface and reduce the collection of dust. L oads are reduced substantially by being shielded by anearly solid fence around the array or other collectors, and this should beexplored.

The experimental program usually consists of force, moment, and pressure data. Pressure data are needed for limiting local deflections of the reflector itself. Array spacing and distance above ground are additional variables. Runs at several air speeds usually esiabli hthat there is little variation with Reynolds number. The tunnel speed range is chosen based on historical wind records at the proposed site. An example of an in tallation to evaluate the effect of wind screens is shown in Figure 2.

Radar Antennas and Satellite Television Receivers The same type of experiments described above for solar collectors may be made for radar antennas or other dish-type receivers.

A major difference is that one would not expect 0 find them in arrays. As local winds may be quite high, it is not unusual to find them protected by radar-transparent domes. For wind tunnel experiments on exposed antennas themodel sbould be mounted the tunnel on top of the same structure it will see in the field-trailer, antenna stand, small house, and so on. Measurements of drag. I fthere is any question at all about Itructural integrity, pressure measurements should betaken near corners particularly on the dome, if one is to be used.

Figure 13shows anexample of data onthe forces and torque for adifferent shaped antenna, and Above-Water Parts of Ships performance of sails have been evaluated in wind tunnels in limited numbers the year M h ' In general, sail embrace measurements of side force, drag.

These usually embrace f or ground plane model cut off at the waterline, with measurements made of. Again, a wind should be provided as above.

Courtesy Glenn L. Marlin Wind Tunnel. Both sail and ship model experiments should have their data corrected for wake and solid blockage. The models should be kept small enough so that at a yaw angle of 90 bow and stem remain no less than half a ship length from the tunnel walls. Extreme care to duplicate model detail, such as ships' railings, ventilators, and mast detail, are not warranted in studies to reduce aerodynamic drag.

Experiments on speed boats are primarily to find a body shape that has mini- mum nose-up characteristics. Here the model is set at a range of pitch angles about the stern, and the angle at which the aerodynamic moment overcome the moment clue to gravity and thrust about the stern is determined.

The current wide, flat- bottomed speedboats can survive only a few degrees of nose up before they be- come unstable. A relatively recent problem that arises with tankers carrying liquid natural gas is ascertaining that the vents needed as the gas boils off do not constitute a fire hazard.

Bridges The effect of natural winds is important to the proper design of long or even intermediate bridge spans. There has been at least one case in which aerodynamic excitation at quite low wind speed led to fatigue cracking of high aspect ratio 1 beams in a bridge superstructure. Two wind instabilities must bestudied: 1 vortex shedding, which causes limited vertical movement or torsional oscillations at gener- ally low wind speeds: or 2 flutter instability, which can result in both vertical movement and torsional oscillation.

Four types of experiments have been tried: 2. Data from elliptic dish-type radar antenna. Drag component includes sup- 1. Section models would of course be desirable for case of construction especially Sinceth fi l" desi. Full models in turbulent au are the best 1i b f. Wardlaw" considers scaling laws for bridge experiments.

They are used to determine wind loads on buildings, air pollution dispersion patterns, soil erosion, snow drifts, now patterns in the vicinity of building complexes, and so on.

These are sometimes referred to as "meteorological wind tunnels. Instead it is manipulated to obtain a now distribution that is nonuniform in time and pace to represent the atmospheric boundary layer," The features of the atmospheric boundary layer are very different for various terrain characteristics so the tunnels must have ability to adjust the flow to simulate a variety of circumstances.

This is accomplished by having adjustable roughness elements along the floor of the tunnel for as much as test-section widths upstream of the zone inwhich the model is positioned. The Boundary Layer Wind Tunnel Facility at the University of Western Ontario even has an extended water pool to help in simulating now in the marine boundary layer.

Fortunately, the required flow speeds are typically quite low so the power requirements for environmental wind tunnels are not so high as for vehicle development wind tunnels. The material in this section is complementary to material in Chapter 6 on wind engineering. Experimental methods for environmental studies were done first in general- purpose wind tunnels, with considerable effort going into methods to develop appro- priate si mulation of the planetary boundary layer in the minimum possible strearnwise distance.

However, the methods have developed over the last two to three decades into quite specialized and sophisticated procedures that are required to deal with the highly nonuniform and unsteady flows and their effects. A new term has entered the technological lexicon. It is wind engineering. Wind engineering combines the fields of meteorology, fluid dynamics. In general four separate areas are srudied: I. Wind Forces on Buildings and Structures. These problems are concerned with forces, moments, deflections, local pressures, and velocities.

Dynamics of Structures. This area includes buffet, flutter, swaying, and breathing. Local Winds. These problems require measuring mean wind velocities, turbu- lence, and turbulence energy and scales. Mass Transport by Winds. This covers soil erosion, pollution, blowing soil, efflux from smokestacks, and diffusion. Reynolds numbers for buildings are commonly based on WIdth w. The Rossby number is concerned with the effect of the rotation of Earth on its winds.

It accounts for a change of wind direction of perhaps 5 in ft Thi. For example, at a scale I : a ft building will be 2 ft high. The boundary layer must be matched to at least 3 ft high, and preferably all the way to the test-section ceiling.

The boundary layer velocity distribution and turbulence can be well duplicated by an installation of spires in the entrance cone lowed by a roughness run of J O-l5 test-section heights often made with small eubes on the floor. The longitudinal pressure gradient normally found in a wind tunnel and exaccr- a. I e It IS necessary to provide cooled or heated air and test-section floor areas some types of experiments on pollution, the runnel engineer gets a break for welre.

For these experiments simulat- e boundary layer structure and turbulence is adequate. Nor does the atmosphere have only one temperature gradient oth daily and seasonal changes OCcur. These include smoke, "snow material," erosion experiments with sand, when model failure is part of the experi- ment roofing material or gravel , or when a water trough or structural failure may damage or rust balance components.

Air pollution experiments sometimes require that the tunnel be run at very low velocities. A direct-current drive motor plus a variable-pitch propeller is the best arrangement for this, but an alternating-current motor with avariabl.

Adjusting runnel peed by rpm ISless necessary with thick boundary layer flow because the flow pattern is adjusted by the spires and roughness. Static Loads and Associated Experiments on Buildings Wind tunnel engineers may be called upon to help correct buildings already built and in trouble or to Imide the architect ina new design.

These expenments are more tense than those on proposed buildings because the architect is usually very defensive. On proposed designs it is less costly to make changes. A full building experiment program encompasses the following: I. Preliminary smoke experiments to search for possible trouble spots where' pressure ports are needed. Static wind loads, which may lead to dynamic experiments later. Ventilation intake studies with smoke being emitted by nearby factories or efflux from the proposed building itself.

The high wind velocities near the topof abuilding re ult inahigher total pressure near the topand wind blowing downward. Thi can lead to a variety of unexpected intake problems. Local high-velocity areas that might cause problems for people. We ship to PO Box, addresses.

We may ship the books from multiple warehouses across the globe, including India depending upon the availability of inventory storage. In case of orders from Europe, custom charges may comply by the relevant government authority and we are not liable for it. Please feel free to contact us for any queries. Customer Satisfaction Guaranteed. Besides, you will certainly likewise love this publication Low Speed Wind Tunnel Testing, By Alan Pope, John Joseph Harper to check out due to the fact that this is among your referred publications to check out.

Starting to have reading practice can be undergone from various methods and from alternative kinds of publications. Negotiating with reviewing habit is no requirement. It is a point that will change your life to life much better. It is the important things that will offer you numerous points around the world as well as this universe, in the real life and below after. December 15, History. Harper This edition was published in by Wiley in New York. Written in English — pages. Subjects Wind tunnels.

Not in Library. Harper First published in Subjects Wind tunnels.