Axial ventilation fans are used to improve the air quality, remove contaminants, and to control the temperature and humidity in occupied areas. Ventilation fans are one of the most harmful sources of noise due to their close proximity to occupied areas and widespread use. The prolonged exposure to hazardous noise levels can lead to noise-induced hearing loss. Consequently, there is a critical need to reduce noise levels from ventilation fans. Since fan noise scales with the 4-6th power of the fan tip speed, minimizing the fan tip speed and optimizing the duct geometry are effective methods to reduce fan noise. However, there is a tradeoff between reducing fan speed, noise and aerodynamic efficiency. To this end, a new innovative comprehensive optimum design methodology considering both aerodynamic efficiency and noise was formulated and implemented using a multi-objective genetic algorithm. The methodology incorporates a control vortex design approach that results in a spanwise chord and twist distribution of the blades that maximize the volumetric flow rate contribution of the outer radii, i.e. the axial flow velocity increases from the fan hub to the tip. The resulting blade geometry generates a given volumetric flow rate at the minimum fan tip speed. The fan design is complemented by the design of the optimum inlet duct geometry to maximize volumetric flow rate and minimize BL thickness for low noise generation. Good agreement with experimental results validates the design process. The present study also incorporates multi-element airfoils to further increase the aerodynamic characteristics of the fan blades and enable lower fan speeds and noise. Good agreement between experiments and predictions indicate that traditional blade element momentum methods can be implemented in conjunction with multi-element airfoil aerodynamic characteristics with good accuracy. A direct comparison of fans designed with single and multi-element airfoils has shown that fans designed with multi-element airfoils aerodynamically outperform single element fans. / Doctor of Philosophy / Axial ventilation fans are widely used to improve the air quality, remove contaminants, and to control the temperature and humidity in occupied areas. However, high noise levels from ventilations fans are a harmful source of noise that can lead to irreversible noise-induced hearing loss. Therefore, this work addresses a critical need for quiet and efficient ventilation fans. To this end, a new innovative comprehensive optimum design methodology considering both aerodynamic efficiency and noise was formulated, implemented, and tested. The methodology optimizes the fan geometry to maximize the volumetric flow rate and minimize noise. The fan design is complemented by the design of the optimum inlet duct geometry to increase the volumetric flow rate and minimize BL thickness for low noise generation. Good agreement with experimental results validates the design process. The present study also incorporates multi-element airfoils to further increase the aerodynamic characteristics of the fan blades. A direct comparison of fans designed with single and multi-element airfoils has shown that fans designed with multi-element airfoils aerodynamically outperform single element airfoil fans.

The adjustable-pitch setting on an axial-flow fan is the most common method of controlling airflow for primary coal mine ventilation. With this method, the fan operates at a constant speed dictated by its motor design. The angles of the blades are adjusted to change the amount of airflow and pressure to meet ventilation requirements. Typically, the fan does not operate at its optimum efficiency, which only occurs in a narrow band of air pressures and quantities. The use of variable frequency drives (VFDs), which control fan speed, provides a solution to this problem. VFDs are already used in various similar applications such as pumping and building ventilation. New technology now enables efficient VFD operation in medium voltage (2,300 – 6,900 V) fan applications. The primary benefit of a variable frequency drive is that it allows motors to operate at reduced speeds, and thus at a lower power, without a loss of torque. VFDs also allow for efficient operation over the entire life of the fan. The technical considerations of using a VFD are presented in this work, along with a method for choosing and modeling a variable speed fan to achieve maximum energy savings. As a part of this research, a spreadsheet program was developed that will calculate the optimum fan operating speed based on given fan data and specified operating conditions. A representative room and pillar coal mine is modeled to illustrate the selection and modeling process and as an example of the economic implications of using a VFD. The use of VFDs is shown to potentially yield large energy savings by increasing the fan efficiency over the life of the mine. Although there are definite power savings while using variable speed fans, the magnitude of these savings is specific to an individual mine and the operating conditions encountered. The determination of whether the use of VFDs is economically feasible requires analysis for the specific mine and its operating conditions. This work provides the background and a method for such an evaluation. / Master of Science

Ducted fan VTOL UAVs are currently being designed for use by the Army for surveillance and reconnaissance in the battlefield. The vehicle tested in this research is part of the Honeywell MAV program. Able to be carried in a backpack by a single soldier, it has a duct diameter of 11.5-in. and weighs approximately 20-lbs at takeoff. It is designed for flight up to 50-knots with fan speeds varying between 5000 and 8500 RPM. Reynolds numbers, based on the duct diameter, were on the order of Re = 0.96 x 106 to 4.6 x 106. Various control effectors were mounted to the vehicle and tested for maximum control authority to reduce the nose-up pitch moment created during forward flight or with crosswinds present. Static and wind tunnel tests were conducted to measure each control effector's performance. Box vanes, mounted downstream of the duct, utilized four assemblies, each with three vanes and one flap. This configuration showed adequate results in generating a nose-down pitch moment. Duct deflectors, mounted on the windward strut upstream of the duct, reduced the windward lift produced by both the fan and duct, resulting in a nose-down pitch moment. Opposed vanes, utilizing two vanes and flaps for each of the four assemblies, were designed with the same surface area as the box vanes. With each pair capable of independent vane movement, the opposed vanes were tested with the vanes rotating in tandem for a basic elevator deflection and with the leading edges touching, disrupting the flow at the duct exit. Opposed vanes combined the capabilities of the box vanes and duct deflector. Results show that the opposed vanes were the most practical control effector, offering the most control authority for maximum nose-down pitch moment (up to 80% better) with minimal loss in thrust. / Master of Science

In order to improve the flight performance of the Martin Jetpack research was undertaken to investigate the aerodynamic issues that were limiting the P-11A Jetpack's flight envelope. Through research of existing ducted-fan aircraft, a flight model describing the unique aerodynamics of the Martin Jetpack was developed using Matlab®/Simulink® software. The dynamic flight model, which can be ran in real time, includes the reactions from: ducted-fans, aircraft body aerodynamics, control surfaces, gyration and landing gear interactions. Abstract Numerous experiments were designed to quantify and validate assumptions used in the development of the model equations. The experiments took advantage of the small size of the Jetpack by designing and building test apparatuses that measured reactions directly on the actual aircraft. This avoided scaling issues that are traditionally encountered when employing wind tunnels for aerodynamic measurements. Abstract Implementing the experimental results into the model led to the modifications of the existing Jetpack airframe to produce the P-11C Jetpack prototype, which significantly improved the performance of the aircraft. The collected flight data was used to validate the model and good agreement was achieved. Abstract Based on this research a new Jetpack prototype (P-12) was developed that combined the flight performance of the P-11C Jetpack with the ability to carry a man or manned sized payload. The model was used to design the layout and to size the control vanes for the P-12 Jetpack. Further research was performed to design larger rotor and stator blades required for the P-12 Jetpack prototype. Abstract The developed model allows the user to efficiently evaluate various control methodologies and changes to key aerodynamic features of the aircraft to aid in the design and flying of the Martin Jetpack. Abstract The outcome of this research is a better understanding of the ducted-fan technology, and via the development of the Jetpack flight model, correctly applying this understanding to improve the Jetpack's flight performance.

何崇謙. / Thesis (M.A.)--香港中文大學硏究院藝術系 / Includes bibliographical references (leaves 147-160). / He Chongqian. / Thesis (M.A.)--Xianggang Zhong wen da xue yan jiu yuan yi shu xi. / 序言 --- p.I / Chapter 第一章 --- 導言 --- p.1 / Chapter 第二章 --- 摺扇的沿革 --- p.8 / Chapter (一) --- 摺扇的起源 --- p.8 / Chapter (二) --- 摺扇在中國的發展 --- p.14 / Chapter 第三章 --- 摺扇繪畫概說 --- p.25 / Chapter 第四章 --- 明代摺扇山水畫的藝術 --- p.35 / Chapter (一) --- 吳派 --- p.39 / Chapter 甲 --- 沈周 --- p.39 / Chapter 乙 --- 文徵明 --- p.43 / Chapter 丙 --- 吳門子弟 --- p.49 / Chapter 1 --- 陳淳 --- p.50 / Chapter 2 --- 陸治 --- p.51 / Chapter 3 --- 文嘉 --- p.53 / Chapter 4 --- 文伯仁 --- p.57 / Chapter 5 --- 錢穀 --- p.59 / Chapter 丁 --- 小結 --- p.61 / Chapter (二) --- 院體派 --- p.61 / Chapter 甲 --- 周臣 --- p.62 / Chapter 乙 --- 唐寅 --- p.66 / Chapter 丙 --- 仇英 --- p.70 / Chapter 丁 --- 小結 --- p.74 / Chapter (三) --- 松江派 --- p.75 / Chapter 甲 --- 莫是龍 --- p.75 / Chapter 乙 --- 宋旭 --- p.77 / Chapter 丙 --- 董其昌 --- p.79 / Chapter 丁 --- 趙左 --- p.85 / Chapter 戊 --- 宋懋晉 --- p.87 / Chapter 己 --- 小結 --- p.89 / Chapter (四) --- 變形派 --- p.90 / Chapter 甲 --- 丁雲鵬 --- p.91 / Chapter 乙 --- 吳彬 --- p.94 / Chapter 丙 --- 藍瑛 --- p.97 / Chapter 丁 --- 陳洪綬 --- p.99 / Chapter 戊 --- 小結 --- p.102 / Chapter 第五章 --- 結論 --- p.104 / 註釋 --- p.115 / 參考書目 --- p.147 / 圖錄 --- p.161

Desde a última década, as autoridades aeronáuticas dos países membros da ICAO vem, gradativamente, aumentando as restrições nos níveis de ruído externo de aeronaves, principalmente nas proximidades dos aeroportos. Por isso os novos motores aeronáuticos precisam ter projetos mais silenciosos, tornando as técnicas de predição de ruído de motores cada vez mais importantes. Diferente das técnicas semi-analíticas, que vêm evoluindo nas últimas décadas, as técnicas semiempíricas possuem suas bases lastreadas em técnicas e dados que remontam à década de 70, como as desenvolvidas no projeto ANOPP. Uma bancada de estudos aeroacústicos para um conjunto rotor/estator foi construída no departamento de Engenharia Aeronáutica da Escola de Engenharia de São Carlos, permitindo desenvolver uma metodologia capaz de gerar uma técnica semi-empírica utilizando métodos e dados novos. Tal bancada é capaz de variar a rotação, o espaçamento rotor/estator e controlar a vazão mássica, resultando em 71 configurações avaliadas. Para isso, uma antena de parede com 14 microfones foi usada. O espectro do ruído de banda larga é modelado como um ruído rosa e o ruído tonal é modelado por um comportamento exponencial, resultando em 5 parâmetros: nível do ruído, decaimento linear e fator de forma da banda larga, nível do primeiro tonal e o decaimento exponencial de seus harmônicos. Uma regressão superficial Kriging é utilizada para aproximar os 5 parâmetros utilizando as variáveis do experimento e o estudo mostrou que Mach Tip e RSS são as principais variáveis que definem o ruído, assim como utilizado pelo projeto ANOPP. Assim, um modelo de previsão é definido para o conjunto rotor/estator estudado na bancada, o que permite prever o espectro em condições não ensaiadas. A análise do modelo resultou em uma ferramenta de interpretação dos resultados. Ao modelo são aplicadas 3 técnicas de validação cruzada: leave one out, monte carlo e repeated k-folds e mostrou que o modelo desenvolvido possui um erro médio, do nível do ruído total do espectro, de 2.35 dBs e desvio padrão de 0.91. / Since the last decade, the countries members of ICAO, via its aeronautical authorities, has been gradually increasing the restrictions on external aircraft noise levels, especially in the vicinity of airports. Because that, the new aero-engines need quieter designs, so noise prediction techniques for aero-engines are getting even more important. Semi-analytical techniques have undergone a major evolution since the 70th until nowadays, but semi-empirical techniques still have their bases pegged in techniques and data defined on the 70th, developed in the ANOPP project. An Aeroacoustics Fan Rig to investigate a Rotor/Stator assembly was developed at Aeronautical Engineering Department of São Carlos School of Engineering, allowing the development of a methodology capable of defining a semi-empirical technique based on new data and methods. Such rig is able to vary the rotation, the rotor/stator spacing and mass flow rate, resulting in a set of 71 configurations tested. To measure the noise, a microphone wall antenna with 14 sensors were used. The broadband noise was modeled by a pink noise and the tonal with exponential behavior, resulting in 5 parameters: broadband noise level, decay and form factor and the level and decay of tonal noise. A superficial kriging regression were used to approach the parameters using the experimental variables and the investigation has shown that Mach Tip and RSS are the most important variables that defines the noise, as well on ANOPP. A prediction model for the rotor/stator noise are defined with the 5 approximation of the parameters, that allow to predict the spectra at operations points not measured. The model analyses of the model resulted on a tool for results interpretation. Tree different cross validation techniques are applied to model: leave ou out, Monte Carlo and repeated k-folds. That analysis shows that the model developed has average error of 2.35 dBs and standard deviation of 0.91 for the spectrum level predicted.

<p>This thesis is a study of how cooling fan control can be improved by using road topography information. Two such controllers are presented, one that uses information available in vehicles produced today, and one that combines GPS-information with digital topographic maps to use information about the road ahead of the vehicle.</p><p>Simulations show that significant energy savings can be obtained, especially during warm conditions and hilly roads. Compared to conventional fan controllers, energy consumption can be cut by up to three quarters. Moreover, this is possible without any hardware redesign.</p>

This thesis is a study of how cooling fan control can be improved by using road topography information. Two such controllers are presented, one that uses information available in vehicles produced today, and one that combines GPS-information with digital topographic maps to use information about the road ahead of the vehicle. Simulations show that significant energy savings can be obtained, especially during warm conditions and hilly roads. Compared to conventional fan controllers, energy consumption can be cut by up to three quarters. Moreover, this is possible without any hardware redesign.

Šiuolaikinio profesionalaus sporto specifika lemia, kad profesionalių sporto klubų sėkminga veikla, sportiniai pasiekimai yra priklausomi nuo tikslinių auditorijų. Todėl ir sporto klubų komunikacija turi būti atitinkamai formuojama atsižvelgiant į tų tikslinių auditorijų poreikius ir lūkesčius. Sporto marketingo komunikacijos tyrėjai sutinka, kad gerbėjai, svarbi ir gausiausia sporto klubų tikslinė auditorija, galinti tarnauti ir kaip kanalas kitoms tikslinėms auditorijoms pasiekti. Todėl galima daryti prielaidą, jog gerbėjų klubai, sudaryti iš aktyviausiai palaikančių komandą individų, vaidina esminį ir specifinį vaidmenį profesionalių sporto klubų komunikacijos formavime. Šio darbo teorinėje dalyje nagrinėjama sporto marketingo komunikacijos specifika, išskirtinumas lyginant su tradicine marketingo samprata. Nustatomos pagrindinės profesionalių sporto klubų tikslinės auditorijos ir jų svarba minėtiems sporto klubams. Toliau nagrinėjami gerbėjų bazės formavimosi teoriniai modeliai, ypatingą dėmesį skiriant socialinio identiteto ir savęs atitikimo teorijoms. Taip pat išskiriami ir analizuojami atspindėtos šlovės įsisavinimo, atspindėtos nesėkmės atmetimo fenomenai bei spindesio efektas. Nagrinėjamos gerbėjų tipologijos, sudaryta apibendrinta gerbėjų tipų klasifikacijos schema. Teorinė dalis yra pabaigiama profesionalių sporto klubų vykdomos sporto marketingo komunikacijos ir gerbėjų santykio analize. Šio darbo tyrimu siekiama išnagrinėti komunikacinį santykį tarp... [toliau žr. visą tekstą] / Specifics of modern professional sports determine that successful activities of professional sports clubs, achievements are depended on target audiences. So communication of sports clubs also has to be shaped accordingly to mentioned target audiences needs and expectations. Sports marketing communication researchers agree that fans are important and the most numerous target audience and sports clubs, which can also serve as a communication channel to reach the rest target audiences. So presumption can be made, that fan clubs, containing of the most active supporters, acts a fundamental and specific role in formulating professional sports clubs communication. In theoretical part of this work specific of sports marketing communication and its oneness comparing to traditional conception of marketing is analyzed. Also, main target audiences of sports clubs and their importance are determined. Furthermore, fan base formation theoretical models are analyzed, giving special attention to social identity and self congruity theories. Moreover, basking in reflected glory, cutting off reflected failure phenomenon and the halo effect are distinguished and analyzed. Typologies of fans are studied; generalized fan types classification scheme is made. Theoretical part of this study is finished with sports marketing communication and fans relation analysis. This case research purpose is to analyze the communicative relation between professional sports club and fan club. Kaunas “Žalgiris“... [to full text]

Universiẗat, Diss., 2005--Saarbrücken.