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Digitized by Kansas Correctional Industries

During the past two summers at the Institute of Oceanography of the University of British Columbia a research group has been involved in an experimental programme studying the interaction between the air and the sea close to the ocean surface. To date instruments have been developed and used to measure the vertical flux of momentum and the waves on the water surface. The observational site is situated on the tidal flat, Spanish Banks, in Burrard Inlet. Though the fetch is limited measurements are considered to be representative of the air flow close to the sea surface. The most important influence driving the ocean circulation is thought to be the momentum transferred through the atmospheric boundary layer. Although quantities such as heat and water vapour are also transferred, this thesis concerns only the transport of momentum. From profiles of wind speed measured over the sea at six heights up to five meters the downward transport of momentum is deduced. Whenever possible this momentum transport is compared to other estimations of this quantity, obtained by means of the hot wire anemometer. The various conditions of atmospheric stability are recorded and used in association with wind profile studies. Another important aspect of the wind profile study of this thesis is to determine the optimum averaging time for wind speeds in order that they may give meaningful estimates of the vertical transport of momentum. Furthermore, wind profiles are compared critically for fluctuating winds of approximately ten minute duration with the hope of discovering the influence of waves on the air flow close to the surface. The surface drag coefficients are inferred from the wind profiles and results are compared to those of other workers. The influence of the other measured variables on drag coefficients, such as wind speed, stability, and fetch, is studied. Several spectra of the low frequency downwind velocity fluctuations are computed and these results are compared with the spectra obtained by other workers and in addition with a hot wire anemometer spectrum. For one run enough 10 second-averaged velocities are available to calculate, with a reasonable degree of certainty, the statistics of the distribution of the downwind velocity components. The results from the past two summers presented in this thesis should be regarded as a preliminary investigation of some of the physical processes of air-sea interaction. By no means all the determining factors as yet have been successfully measured. At this stage a more thorough understanding of the behaviour of the instruments for measuring the transfer of momentum and a preliminary understanding of the physical processes involved has been gained. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

One very important part of research is the development of effective, reliable instruments. The measurement of turbulence in flow fields is a complex research problem. It depends heavily upon the hot-wire anemometer. This thesis describes the evaluation and use of a constant- current hot-wire anemometer, and presents the equations governing its use for turbulence measurements. The thesis first enumerates and explains some of the important parameters of turbulent flows, providing the basis for the discussion of their measurement which follows. The cooling of a heated wire in forced convection and a typical anemometer circuit are discussed. Derivations of the instrument equations are presented to illuminate the instrument's operation. Two wire arrays and their use are explained and techniques for the measurement of the intensities, correlation coefficients, and integral scale of turbulence are described.

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Detaljerad information om vindförhållandena på en site är en nödvändighet för att göra beräkningar av lönsamhet i ett vindkraftsprojekt. Mätningarna behöver vara kontinuerliga och så korrekta som möjligt. Därtill bör de göras under minst ett års tid eftersom vindförhållandena på en plats är säsongsberoende. Under vintertid och framför allt på högre latituder eller altituder, kan mätutrustning påverkas av nedisning. En nedisad anemometer kan ge databortfall eller felaktiga mätningar. Identifiering av felaktiga data är en viktig del av analyseringsarbetet eftersom risken annars är att vindförhållandena på platsen underskattas. Då instrumentet är helt fastfruset kan en enklare analys av data göras genom att titta på standardavvikelsen av vindhastigheten. Svårigheten i detektionen är vid lätt till måttlig nedisning då vindstyrkan, och även standardavvikelsen, kan se normal ut trots att felaktiga värden redovisats. I detta arbete analyseras 1 Hz data från skålkorsanemometer för att söka ett matematiskt sätt att avgöra om lätt till måttlig nedisning påverkat instrumentet under mätperioden. I ett experiment har olika typer av nedisning simulerats på skålkorsanemometrar. Därefter har vindhastighetsfördelningen för en ”nedisad” anemometer kunnat jämföras med fördelningen uppmätt med en anemometer som varit opåverkad under samma mätperiod. I denna jämförelse har visats att trots en differens i medelvind-hastighet på upp till 15 % under mätperioden syns ingen, för detektion av nedisning, användbar skillnad i någon av de statistiska parametrar som jämförts i arbetet. Förutom analys av mätdata från egna experiment har även data från Suorva samt från en höghöjdsmast i Norrland analyserats. För analys av mätdata från masten i Norrland har ett en algoritm utarbetats för automatisk detektion av tidpunkter med instrumentell nedisning. Isdetektionen baseras på antaganden om standardavvikelse av vindhastighet och vindriktning, förändring av vindriktning samt en regression mellan vindhastigheten på två höjder. / Detailed information about the wind conditions on a site is a necessity for calculations of profitability from a wind power project. Hence the continuity and the correctitude of the measurements are crucial when making the site evaluations. Due to the season dependence of the wind conditions the measurements also needs to be done for at least a whole year. During wintertime and particularly on higher altitudes and/or latitudes the instruments may be affected by icing. An iced up anemometer often underestimates the wind speed and severe icing can lead to instrument breakage and loss of data. Identification of inaccurate measurements is of great importance in the analysis of the site’s energy potential. The difficulty in detecting light to moderate icing lies in that the wind speed and the standard deviation of the wind may seem normal, although the anemometer is underestimating the wind speed due to icing. In this thesis 1 Hz data from cup anemometers are analysed in search for a mathematical way to determine whether the instrument has been affected by icing during the measurement. An experiment has been performed simulating different types of icing on anemometers. The wind velocity distribution of an “iced up” anemometer has been compared to the wind velocity distribution of an unaffected anemometer for the same measuring period. Also the turbulence intensity and the change of mean wind velocity between observations have been evaluated. The comparison of these statistical variables between the instruments has showed that none of them are applicable for detection of icing. In addition to analysing data from the experiment a pre-study on the subject has been made analysing measurements with possible icing from the Suorva valley. Also, the results from the experiment have been compared to results from a conventional measuring mast placed in the northern part of Sweden. For the analysis of the mast data an algorithm for detection of icing during measurements has been implemented. This automatic detection of icing is based on assumptions about the standard deviation of wind speed, the standard deviation of the wind direction, the change of wind direction and regression between wind velocities of two heights.

No description available.

<div> <p>The objective of this thesis is to apply high frequency flow measurement technique known as hot wire anemometry to <a>characterize the velocity, turbulence intensity and turbulent length scales in the </a><a></a><a>Purdue Experimental Turbine Aerothermal Lab Rig</a>. Hot wire anemometry has been widely used to characterize velocities and turbulence levels in different environments and using different calibration and post-processing methodologies. In this work, a precise calibration and post-processing method was developed and successfully applied to the state-of-the-art trisonic Purdue Experimental Turbine Aerothermal Lab wind tunnel. The different experimental setups where the turbulence levels were analyzed were fabricated using modern manufacturing techniques such as 3D printing or water cutting. These techniques increase the complexity of the designs to be tested in wind tunnels. Calibration process was then successfully tested in the Purdue Experimental Turbine Aerothermal Lab Rig. Finally, accuracy and sensitivity analysis of the calibration are performed to verify the performance and reliability of the process.</p></div>

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Tunnel ventilation is the design practice of placing exhaust fans and air inlets on opposite ends of animal production facilities and moving air through the building via negative pressure. Increasing air velocity within tunnel ventilated broiler production facilities increases sensible cooling and reduces the need for latent cooling (panting), which improves production efficiency. An air velocity measurement system was developed and measurement density analysis for quantifying air velocity distribution was performed in a 12.19 x 121.9 m commercial broiler production facility. Results showed that axial measurement distances of 3.05 m and 40 measurement points per cross-section produced the most descriptive air velocity distribution maps. Air velocity distribution, mean cross-sectional air velocity, and total facility air flow was assessed in three tunnel ventilated commercial broiler production facilities. These facilities differed in size, design, and equipment configurations (test facility 1 was 18.3 × 170.7 m, test facility 2 was 15.24 × 144.8 m, and test facility 3 was 12.19 × 121.9 m). Air velocity distribution varied within all three facilities. Normalized cross-sectional air velocity was plotted against proportion of total house length to compare the cross-sectional air velocity of the three facilities. House width and physical arrangement of the feed hoppers, heating systems, and tunnel fans are impacting air velocity uniformity and mean cross-sectional air velocity in the three broiler houses. Precision Livestock Farming (PLF) seeks to improve production efficiency and animal well-being by model based control of animal production facilities. Four broiler production facilities were assessed for spatial bird body weight (BW) variability. The facilities were 15.24 × 144.8 m solid side-wall tunnel ventilated broiler houses containing birds at 58 and 59 d of age. Significant differences in BW were found between birds residing at center house (3.47 kg average) and at the side-walls (3.38 kg average) (P = 0.025). This variability in BW could be attributed to any number of environmental, nutrient, or behavioral causes. A discussion of input/control parameters for PLF management of broiler production is presented. Quantification of performance variability within these facilities and defining models for control of input parameters is essential to making PLF management feasible.