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"Since the analytical result of the frictional resistance of a rotating disk has been reported by Kérrnén (l92l), many studies have been done experimentally or analytically on the characteristics of the three-dimensional boundary layer at the disk surface. Frictional resistance of an impeller of a turbo-machinery is calculated by applying that of a rotating disk flow. To improve the performance of a turbo-machinery, attempt was done by applying a drag reduction to the tlow. Thus, the drag reduction phenomena have been studied on a rotating disk in drag reducing additives (Watanabe, K., l978) or a disk with hydrophobic wall (Watanabe, K., and Ogata, S., 1997). However, the drag reducing method reported in the past remains a problem- that the degradation or the durability becomes the iitilure forthe practical application.In this study, the experiments were carried out the measurement on the frictional moment, velocity fluctuation and protlle and flow visualization of an enclosed rotating disk in order to obtain a new passive drag reduction wall that is excellent in the durability and is practically applicable. An approximation theoretical analysis base on the momentum integral equation -also has been accounted for axial clearance ratio effects for the case of separate boundary layers onthe disk. This theory has been checked against experimental results.lt is well known that fluid in the boundary layer ata rotating disk surface flow with keeping a flow angle (Gregory, N. et al., 1955); By considering this flow pattern, was made a disk with a new passive drag reduction wall by an etching method. The disk with many fine spiral grooves is made of aluminum. The number of the spiral grooves varying at 120, 144, 150, 155 and 160 with 0.l and 0.2 mm depth each. The clearance between the disk and the housing wall was varied at l, 3, IO, 20 and 30 mm thick. Experimental result showed that for the close clearance l mm the moment coefficient in the turbulent region in the Reynolds number range of 4x 10" S Re S 6x 10? for the disks of l50 and |55 grooves with 0.1 and 0.2 mm depth, the drag reduction ratio was obtained about 15 %. While for the large clearance 20 mm for the disk of 144,150 and 155 grooves with 0.1mm depth in the Reynolds number range of 3.3 x to? < Re <4.0x105 the drag reduction ratio was obtained about 11 % .The experimental results of the velocity fluctuation, velocity profile and the flow visualization also add other evidences: the fine spiral grooves control the secondary flow of the boundary layer and have the effect which delays the generation oft he local turbulence in the transition range, and reduce wall skin friction in the turbulent region."

"In this study, the limiting maximum drag reduction asymptote for the moment coefficient of an enclosed rotating diskwith fine spiral grooves in turbulent flow region were obtained analytically. Analysis which were based on anassumption for a simple parabolic velocity distribution of turbulent pipe flow to represent relative tangential velocity,was carried out using momentum integral equations of the boundary layer. For a certain K- parameter the momentcoefficient results agree well with experimental results for maximum drag reduction in an enclosed rotating disk withfine spiral grooves and drag reduction ratio approximately was 15 %. Additionally, the experimental results for dragreduction on a rotating disk can be explained well with the analytical results."

"Nikola Tesla, seorang inventor dan engineer, pada tahun 1913 mempatenkan suatu invensi yang dinamakan olehnya ‘Turbine’ yang kemudian lebih sering direferensi sebagai Tesla Turbine, sebuah turbin non-konvensional tanpa bilah yang bekerja menggunakan prinsip boundary layer. Dalam percobaan ini, penulis berusaha untuk mengoptimalkan kerja turbin menggunakan cetakan alur (groove) spiral tipis di permukaan cakram untuk memandu jalannya fluida. Skripsi ini akan mencoba beberapa konfigurasi bilah turbin seperti normal, face-to-face, dan same side yang diuji pada kondisi yang sama untuk menentukan beda RPM dan efisiensi. Dari percobaan ini, akan ditemukan perkembangan efisiensi berkat surface finishing yang dilakukan kepada bilah turbin dibandingkan dengan bilah normal, dimana konfigurasi face-to-face mendapatkan efisiensi paling tinggi dibandingkan dengan bilah - bilah lainnya.

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In 1913, inventor and engineer Nikola Tesla patented a certain invention he named ‘Turbine’, which would grew in popularity as Tesla Turbine, which is a non-conventional bladeless turbine that works using the principle of boundary layer. In this paper, the author will attempt to optimalize the performance of the turbine by placing thin spiral grooves along the disks’ surface to guide the flow of the fluid. Here, the author will attempt multiple configurations such as normal, face-to-face, and same side disks that will be tested under same circumstances in order to determine the differences in RPM and efficiency. From this experiment, it will be found that there exists an improvement due to disks’ surface finishing compared to normal disks, where face-to-face configurations will obtain the highest efficiency compared to other configurations."

"ABSTRACTOur present investigation aimed to examine the natural convection boundary layer flow of nanofluids over a vertical flat plate embedded in a saturated Darcy porous medium containing gyrotactic microorganisms. For carrying out the numerical solution, two steps are performed. The governing partial differential equations are firstly simplified into a set of highly coupled nonlinear ordinary differential equations by suitable similarity variables, and then numerically solved by applying the cubic spline collocation technique. The obtained similarity solution depends on non-dimensional parameters, i.e., the bioconvection Lewis number, bioconvection Rayleigh number, bioconvection Peclet number, Brownian motion parameter, the Buoyancy ratio, the thermophoresis parameter, the power-law variation index, and the Lewis number. A comprehensive numerical computation is carried out for various values of the parameters that describe the flow characteristics. Rescaled velocity and temperature distributions are found to be depending strongly on the bioconvection Rayleigh number and power-law variation index parameter. For making the result more reliable a comparison has been shown in the present work with existing results for some special values of governing parameters and the results are found to be in excellent accuracy."

"ABSTRACTThe presented study is focused on experimental investigation of a boundary layeron a flat plate in an adverse pressure gradient. The flat plate is placed in a regular flow, thepressure gradient is generated by the plate inclination. The preceding studies deal with thestructure of the wake behind the plate, the presented study concentrates on the flow structureclose to the suction surface of the plate. The dynamical behavior of the flow structures is studiedin details with respect to the topology in the streamwise direction. In spite of the fact that thetime-mean flow field is close to 2D, more or less constant along the span, the instantaneousstructures topology is fully 3D. Rather oblique structures are detected instead of those orientedin the streamwise direction. The patterns are travelling in the streamwise direction along theplate."

"This book is intended as a text for undergraduate and graduate courses in aerodynamics, typically offered to students of aerospace and mechanical engineering programs. It covers all aspects of aerodynamics. The book begins with a description of the standard atmosphere and basic concepts, then moves on to cover the equations and mathematical models used to describe and characterize flow fields, as well as their thermodynamic aspects and applications. Specific emphasis is placed on the relation between concepts and their use in aircraft design. Additional topics of interest to the reader are presented in the Appendix, which draws on the teachings provided in the text. The book is written in an easy to understand manner, with pedagogical aids such as chapter overviews, summaries, and descriptive and objective questions to help students evaluate their progress. Atmospheric and gas tables are provided to facilitate problem solving. Lastly, a detailed bibliography is included at the end of each chapter to provide students with further resources. The book can also be used as a text for professional development courses in aerodynamics."

"This is the proceedings of the Second International Workshop on Flow Induced Noise and Vibration (FLINOVIA), which was held in Penn State, USA, in April 2016. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those working in the area of flow-induced vibration and noise.Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field.The book describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation; for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays; for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements; for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses."

"This book presents a theoretical study of heat transfer due to laminar natural convection of nanofluids, using Al2O3-water nanofluid as an example. An innovative method of similarity transformation of velocity fields on laminar boundary layers is applied for the development of a mathematical governing model of natural convection with actual nanofluids, and a novel model of the nanofluid's variable thermophysical properties is derived by a mathematical analysis based on the developed model of variable physical properties of fluids combined with the model of the nanofluid's thermal conductivity and viscosity. Based on these, the physical property factors of nanofluids are produced, which leads to a simultaneous solution for deep investigations of hydrodynamics and heat transfer of nanofluid's natural convection.The book also proposes novel predictive formulae for the evaluation of heat transfer of Al2O3-water nanofluid’s natural convection. The formulae have reliable theoretical and practical value because they are developed by rigorous theoretical analysis of heat transfer combined with full consideration of the effects of the temperature-dependent physical properties of nanofluids and the nanoparticle shape factor and concentration, as well as variations of fluid boundary temperatures. The conversion factors proposed help to turn the heat transfer coefficient and rate of fluid natural convection into those of nanofluid natural convection. Furthermore, several calculation examples are provided to demonstrate the heat transfer application of the proposed predictive formulae."