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1
Wallis, Lisa M. Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A comparison of bi-directional disc brake rotor passage designs". Awarded by:University of New South Wales. School of Mechanical & Manufacturing Engineering, 2003. http://handle.unsw.edu.au/1959.4/20312.
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An important part of automobile safety is the braking system. Disc brakes have been widely used in automobiles for sped retardation for over 30 years. During that time, they have developed from a simple disc to a complex disc with channels, vanes, holes and grooves. The stopping capability of disc brakes is affected by the rate at which heat is dissipated by forced convection and the thermal capacity of the rotor. Catastrophic failure of brake rotors can occur during rapid increases or decreases in rotor temperature where regions of high temperature gradients result in high thermal strains. There is little information in the public domain regarding the relative merits of different disc brake rotor geometries, particularly in terms of airflow patterns, heat transfer rates, and internal thermal gradients. The aim of this research project was to investigate how geometrical variations affect the thermal performance of bi-directional disc brake rotors, particularly for high performance applications. Dynamometer testing showed that respectable increases in braking performance are achievable with relatively simple machining modifications. Tuft and smoke visualization techniques provided a preliminary understanding of the airflow in the passages of three distinct bi-directional rotor designs. Particle Image Velocimetry was used for detailed flow measurements which supported the numerical simulations. Computational Fluid Dynamics was used to predict the airflow and heat transfer associated with eight bi-directional brake rotor designs. The results show that 'pillared' passage designs can achieve higher heat transfer rates than traditional straight radial vane designs and that the heat loss from pillared rotors is generally more uniform than from vaned rotors. Subsequent conjugate heat transfer simulations found that temperature gradients inside pillared rotors are typically lower than inside vaned rotors. Thus failure rates due to excessive thermal strain are expected to be lower for pillared rotors. It was shown that rotor selection based solely on heat transfer rates is inappropriate and different passage designs are suited to different applications. The findings of this research will directly benefit local disc brake manufacturers, who do not have resources to conduct thorough studies comparing the thermal characteristics of different brake rotor designs.
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Graf, Aaron John. "Active control of automotive disc bake rotor squeal using dither". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16933.
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Hussain, Jafar. "Thermal and material characterisation of coated lightweight disc brake rotor". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21609/.
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Environmental concerns linked to CO2 emissions have placed the automotive industry under considerable pressure to reduce the carbon footprint of the vehicles that they produce. One way forward involves the use of alternative lightweight materials. The use of aluminium alloy in a brake rotor has the potential to save around 20kg in unsprung mass on a medium sized passenger car. A full scale prototype lightweight coated ventilated aluminium alloy (6082) brake rotor was manufactured to investigate the thermal performance under drag brake test conditions. The brake rotor’s rubbing surface was coated with alumina layer using a plasma electrolytic oxidation (PEO) process. The ventilated brake rotor geometry contributes to the ability of the structure to dissipate heat through the inclusion of an array of appropriately configured vents and so has further bearing on the ability of the rotor to run cool. It is also feasible to explore the impact of vane design on the cooling of the rotor since the vented section of the rotor can be easily reconfigured using the current prototype. Experiments were conducted using a brake dynamometer. Brake rotor rubbing surface temperature, hydraulic pressure, rotational speed and brake torque were monitored during the test. The coefficient of friction was found to be around 0.5. Abaqus software was used to generate a three dimensional finite element model of a section of the coated brake rotor. The simulation results were found to be in good agreement with the experimental results when a heat transfer coefficient of 30 W/m2K was specified on all free surfaces. It was shown that coating thickness has a minimum effect on the substrate temperature. In parallel, a wear analysis has also been carried out using a pin-on-disc experimental setup. The mass of the friction material and the small discs were measured before and after the test. The wear coefficient for both conventional grey cast iron (GCI) and coated aluminium alloy were also measured and compared. It was found that wear rate of the PEO coated disc is about 15 times lower than the GCI. The wear rate of the friction material when run against the PEO coating was about 5 times less than when the same material was run against cast iron, even though the friction coefficient was on average higher (0.6 of 0.5).
4
Perdikologos, Nikolaos Carleton University Dissertation Engineering Mechanical. "Dynamic analysis of flexible disc-rotor systems using component modes". Ottawa, 1985.
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Carter, Jace A. "EFFECT OF MATERIAL ANOMALIES ON FATIGUE LIFE OF TURBINE DISKS". Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316211638.
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Arzpeima, Minoo. "CFD Investigation of Flow Structures in Rotor-Stator Disc Cavity Systems". Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153733.
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Parras, Blázquez Pedro Santiago. "CFD Analysis of Pressure Instabilities in Stator-Rotor Disc Cavity Systems". Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-140904.
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The continuous demand to improve turbine performance has led manufactures to focus on aspects that have been previously considered of secondary importance such as the secondary air system. The purpose of this system is to cool the components and prevent ingestion of hot gas into the stator-rotor cavity that could lead to low frequency pressure fluctuations called Cavity Flow Instabilities. These instabilities could cause unpredictable rotor vibrations and damage several components. A CFD method capable of detecting cavity flow instabilities in a rotor-stator disk cavity system is investigated, based on the 360◦model of the cavity without anystator vanes and rotor blades. Boundary conditions are simplified by considering steady and uniform flow in the main gas path. Different turbulence models are tested such as Realizable k−ε,k−ω SST, DDES, and SAS. In order to test the performance of the method, different purge flow levels are simulated. The most successful results, are predicted by the Realizable k−ε turbulence model. This model predicts two rotating low pressure structures in the cavity, for low purge flow levels. These pressure structures rotate at approximately 80% of the rotor speed. Furthermore, the spectra analysis of the pressure shows a reasonable agreement with the experimental results in terms of the frequency, showing a distinct region of low frequencies pressure instabilities. Nonetheless, this method overpredicts the amplitudes by a factor of 3-7 depending on the frequency. In addition, regions of one order of magnitude higher in frequency is also predicted. The DDES model shows similar findings but the amplitudes in the pressure spectra associated to the low frequencies are lower. Additionally, SAS also predicts the pressure in-stabilities but, in this case, the amplitudes are closer to RANS simulations, yet the high frequencies disappear. Unfortunately, k−ω SST, did not predict these pressure instabilities. Further research is still needed in many of the aspects of this work, from the simplifications up to the turbulence models. However, it is concluded from this work that this method could be a useful tool for turbine design as it decreases the need for testing and prototype manufacturing.
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Amann, Christian [Verfasser], i P. [Akademischer Betreuer] Gumbsch. "Probabilistic Fracture Mechanics of Forged Rotor Disks / Christian Amann ; Betreuer: P. Gumbsch". Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1139360337/34.
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Linder, Johan. "An integrated brake disc and electric drive for vehicle propulsion : A FEASIBILITY STUDY". Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187652.
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In this thesis, the feasibility to integrate an brake disc and electric machine is investigated. In wheel motors (IWMs) have several advantages, such as saving space in the vehicle, individual and direct control at the wheels and the absence of a mechanical transmission. However, today’s IWMs are heavy and, thus, negatively affect the driving performance of the vehicle due to the increase of the unsprung mass. By integrating an already existing part in the wheel, this increase of the unsprung mass can be minimized. The brake disc manages high temperatures, a significant wear in rough environ-ment, which puts high demands on the rotor. The second part of the machine, the stator, will be significantly affected by the high temperatures of the rotor. The temperatures of the stator are transferred by convection, conduction and radiation from the rotor or brake disc. Liquid cooling of the stator back is analyzed as a potential solution for handling the high temperatures. In order to analyze the feasibility of the concept, thermal, electric and mechanical modelling has been used. The evaluation whether it is possible or not to integrate the brake disc has been with regard to the results of weight, cost, thermal tolerance and electric performance.I detta arbete undersöks möjligheten att integrera en bromsskiva med elmaskin. Hjul-motorer har flera fördelar, bland annat sparas utrymme i själva bilen, individuell kontroll samt drivning av hjulen utan mekaniska transmissioner. Men hjulmotorer som kan användas idag väger oftast så pass mycket att den odämpade massan ökar kritiskt och köregenskaper av fordonet då blir lidande. Genom att integrera en befintlig del i hjulet kan ¨okningen av odämpade massan minskas. Att använda bromsskivan som rotor, kräver att denna tål temperaturer ¨over 500◦C samt påfrestningar och slitage som en vanlig mekanisk friktionsbroms måste uthärda. Den andra delen av maskinen, statorn kommer även denna att påverkas av de höga temperaturerna av bromsskivan som kommer ledas via konvektion, konduktion och strålning. Möjligheten att kyla statorn med vätska och om detta är tillräckligt undersöks. För att analyserna genomförbarheten av projektet har termiska, elektriska och mekaniska modeller använts. Resultaten har analyserats där maskinens vikt, kostnad, termisk tålighet och elektrisk prestanda har legat till grund för bedömningen om lösningen; att integrera en broms-skiva med elmaskin är rimlig eller ej.
10
Mitchell, Robert John. "Development of a new powder processed Ni-base superalloy for rotor disc application". Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614731.
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Carvalho, José Filipe Trilha de. "Predição numérica do torque em uma turbina tesla com rotor estacionário". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/174394.
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O presente estudo apresenta a análise numérica do escoamento do fluido de trabalho em uma turbina Tesla com rotor estacionário. O estudo de independência de malha prevê o uso de aproximadamente 2 milhões de volumes, com desempenho semelhante ao das malhas mais refinadas, apresentando uma economia significativa de esforço computacional. Três modelos de turbulência da abordagem RANS são aplicados com o objetivo de estabelecer uma metodologia para estudos futuros com dados experimentais. Os diferentes modelos de turbulência fornecem resultados para a predição do torque na turbina, com uma variação abaixo de 1 % entre si. Ar é usado como fluido de trabalho a pressão manométrica de 2,5 bar, alcançando velocidades no entorno de 310 m.s-1 na região da garganta do bocal e na região de jato livre, logo após a descarga do bocal. Essa condição permite afirmar que a turbina funciona na sua condição de máxima vazão, com o número de Mach próximo ao valor unitário, com escoamento compressível A velocidade na região interna entre discos chega a um valor máximo de 100 m.s-1. Na ausência de dados experimentais e de literatura, um estudo paramétrico com diferentes condições de operação da turbina é realizado a fim de verificar a qualidade dos resultados simulados. A vazão mássica é estimada com base na temperatura e pressão do fluido de trabalho, modelado como gás ideal. Os resultados preditos pelo modelo numérico para o torque no rotor é de 2,09 N.m com pressão manométrica de 1,5 bar e vazão mássica de 33,58 g/s, 2,22 N.m com pressão manométrica de 2,0 bar e vazão mássica de 40,29 g/s, e 2,38 N.m com pressão manométrica de 2,5 bar e vazão mássica de 53,73 g/s. A temperatura foi de 300 K mantida constante para as três análises. Para os casos analisados, o número de Mach na garganta do bocal convergente apresentou uma tendência ao valor unitário, variando entre 0,7 a 1, o que sugere que o bocal está trabalhando na sua condição máxima de vazão do fluido de trabalho.The present study presents the numerical analysis of the working fluid flow in a Tesla turbine with stationary rotor. The mesh independence study predicts the use of approximately 2 million volumes, with similar performance to those most refined meshes, presenting a significant saving of computational effort. Several turbulence models of the RANS approach are applied with the aim of establishing a methodology for future studies with experimental data. The different turbulence models provide very close results for turbine torque prediction, with a variation below 1% between them. Air is used as working fluid at a pressure of 2.5 bar gauge, reaching velocities around 310 m.s-1 in the throat region of the nozzle and in the free jet region, just after the discharge of the nozzle. This condition allows to state that the turbine works in its maximum flow condition, with the Mach number close to unitary value, with a compressible flow The velocity in the inner region between disks reaches 100 m.s-1. In the absence of experimental data and literature, a parametric study with different operating conditions of the turbine is performed in order to verify the quality of the simulated results. The mass flow rate is estimated based on the temperature and pressure of the working fluid, modeled as the ideal gas. The results predicted by the numerical model for the torque in the rotor is 2.09 N.m with gauge pressure of 1.5 bar and a mass flow rate of 33.58 g/s, 2.22 N.m with gauge pressure of 2.0 bar and a mass flow rate of 40.29 g/s, and 2.38 N.m with gauge pressure of 2.5 bar and flow mass of 53.73 g/s. The temperature was 300 K kept constant for all three cases. For the analyzed cases, the Mach number in the throat of the convergent nozzle showed a tendency to the unit value, ranging from 0,7 to 1,0 which suggests that the nozzle is working in its maximum flow condition of the working fluid.
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Hieke, Sebastian, Mario Stamann, Dmytro Lagunov, Roberto Leidhold, Andrii Masliennikov, Aleksei Duniev i A. Yehorov. "Two-phase transverse flux machine with disc rotor for high torque low speed application". Thesis, EPE’17 ECCE Europe, 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/39783.
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This paper presents a special two-phase transverse flux machine with disc rotor. Because of the noncomplex construction and by using simple 2D flux path and 3D printing methods the manufacturing costs are hold low. A design criterion is proposed for maximizing the torque density in the low speed range. To prove the concept and analyse the potential of this construction a first direct driven prototype was built. The experimental results confirm the viability of this proposal and provide the required information for further enhancements.
13
Kremer, Mickaël. "Electromagnetic design of a disc rotor electric machine as integrated motor-generator for hybrid vehicles". Thesis, Mulhouse, 2016. http://www.theses.fr/2016MULH8792/document.
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Cette thèse présente le dimensionnement d’une machine électrique à rotor disque pour la traction de véhicules hybrides. Un état de l’art complet sur les machines électriques à rotor disque permet de montrer que la machine à flux axial à rotor central est la plus adaptée. Différentes géométries du circuit magnétique sont successivement étudiées et comparées par simulations par éléments finis. Pour maximiser le rendement de la machine, les pertes d’origine électromagnétique sont étudiées. Un modèle analytique des pertes par effet de peau dans les conducteurs de cuivre est proposé et validé par éléments finis. Un second modèle analytique estime les pertes par courant induits dans les aimants permanents pour tous les points de travail de la machine se basant sur uniquement trois simulations par éléments finis permettant ainsi un gain de temps important lors du dimensionnement. Deux méthodes de dimensionnement sont comparées : le dimensionnement manuel par essais/erreurs et l’optimisation multi-objectifs. Cette dernière méthode automatise le dimensionnement et permet une optimisation plus pointue et une forte amélioration des performances. Dans ce cas, la densité de couple a par exemple été augmentée de 29%. La machine à flux axial dimensionnée est comparée avec une machine à flux radial pour véhicules hybrides. Cette comparaison révèle le potentiel de la machine à flux axial avec notamment une densité de couple augmentée de plus de 20%. Enfin, deux prototypes ont été construits et mesurés pour valider les simulationsThis PhD presents the design of a disc rotor electric machine for the traction of hybrid vehicles. A complete state of the art enables the selection of the internal rotor axial flux machine which is the most suited to this application. Different geometries of the magnetic circuit are successively studied and compared with finite elements simulations. To maximize the efficiency of the machine losses generated in the magnetic circuit are studied. An analytic model on the skin effect in the copper conductors is proposed and validated with finite elements simulations. A second analytic model estimates the eddy current losses in the permanent magnets for every operating point of the machine based on only three finite element simulations enabling an important time-saving. Two dimensioning methods are compared: the manual dimensioning based on a tries/errors method and the multi-objectives optimization. This last method automates the dimensioning and enables a more refined optimization and a strong improvement of the performances. For example, the torque density has been improved by 29% in that case. The designed axial flux machine is compared to a state of the art radial flux machine for hybrid vehicle. This comparison shows the potential of the axial flux machine with an improvement of the torque density by more than 20%. Finally two prototypes have been built and measured to validate the simulations
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Abuelenin, Sherif Mohamed Abdel-Hady Faissal. "Developing a magnetically suspended disc system for industrial applications, with application on ring spinning". Auburn, Ala., 2005. http://repo.lib.auburn.edu/Send%208-8-07/ABUELENIN_SHERIF_59.pdf.
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Philipp, Katrin, Angelos Filippatos, Nektarios Koukourakis, Robert Kuschmierz, Christoph Leithold, Albert Langkamp, Andreas Fischer i Jürgen Czarske. "In-process deformation measurements of translucent high speed fibre-reinforced disc rotors". SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35189.
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The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an
important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.
16
Parent, Marie-Océane. "Prédiction de la stabilité en contact rotor-stator dans les turboréacteurs d'avion". Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0004/document.
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L’objectif de ces travaux est de prédire la stabilité dynamique d’un moteur d’avion de type turbofan, lors de contacts légers entre l’extrémité des aubes et le carter en regard. Une voix d’amélioration des performances des turboréacteurs d’avion consiste, en effet, à réduire les jeux entre les extrémités des aubes en rotation et le carter. Réduction qui s’accompagne d’une augmentation des possibilités de contact entre ces parties tournantes et fixes pouvant conduire à des phénomènes vibratoires instables. La démarche proposée s’appuie sur un modèle hybride qui introduit de manière simplifiée une roue aubagée et un carter flexible à un modèle de ligne d’arbres. Une formulation dite 3D du contact a également été implémentée, elle intègre la cinématique des différents organes du modèle et introduit de manière précise la géométrie locale de la zone de contact. Le comportement du modèle lors de contacts aubes-carter est alors étudié en distinguant les analyses menées en supposant un contact permanent et celles autorisant l’intermittence des contacts. Les résultats obtenus mettent en évidence l’importance des couplages introduits dans l’apparition des phénomènes instables et la pertinence de la formulation 3D dans la prédiction de la stabilité du systèmeThis work aims to predict the dynamic stability of a turbofan engine submitted to light contacts between blade tips and casing. Reducing the clearance between the rotating blades and the casing improves indeed the performances of turbomachines ; however, it also increases the possible contacts between rotating and stationary parts, which can cause unstable dynamic behavior. The approach is based on a hybrid model which introduces a simplified bladed wheel and a flexible casing to a rotor-shaft model. A 3D contact formulation has also been implemented ; it considers the model kinematic and introduces the local geometry of the contact area. The model behavior with blade-to-casing contacts is analyzed through two approaches : the first one assumes permanent contacts while the other one allows contact intermittence. The results highlight the importance of couplings in the outbreak of unstable phenomena and the relevance of the 3D contact formulation in predicting the stability of the system
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Studer, Martin. "Ablauf schneller Reaktionen in Rotor-Stator-Mischern verschiedener Grösse /". [S.l.] : [s.n.], 1990. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9037.
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Labský, Jiří. "Konstrukční návrh drtiče větví". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229457.
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The aim of this master's thesis is to design of wood chipper connected to the tractor ZETOR 3011. In the introduction of this thesis it is described the general use of wood chippers. First part of thesis contains recherche from wood chippers' area. Then it is followed with the description of the own chipper design and with the basic design calculations. Part of the thesis is 3D model of the machine and drawing documentation of selected parts. Next part is given economic evaluation. In the last part of thesis is made analysis of risk.
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Colombo, Francesco. "Service-like thermo-mechanical fatigue characteristics of 1CrMoV rotor steel /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17070.
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Babbi, Giulia. "Studio preliminare delle prestazioni di un elicottero a rotori sincronizzati". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Il progetto preso in esame in questa tesi è un elicottero a rotori sincronizzati; lo scopo è determinare le prestazioni, in termini di potenza necessaria al volo, attraverso l'elaborazione di un modello matematico implementato in ambiente Matlab, di una sua riproduzione in scala ridotta alimentata da motore elettrico.
Questo particolare tipo di configurazione non ha il rotore di coda ed ha alta stabilità; tuttavia la caratteristica di avere rotori inclinati dà luogo a forze aerodinamiche di portanza aventi un'angolazione pari a quella dei rotori e ciò causa una riduzione di efficienza totale.
In primo luogo, è stata esposta la teoria del disco attuatore, con le rispettive ipotesi; di seguito, l’elaborazione del modello analitico è stata svolta facendo riferimento alla teoria precedentemente descritta, applicata alla configurazione del sincrottero. Nella tesi viene analizzato l’andamento della potenza necessaria in funzione di diversi parametri sia in condizione di hovering sia in volo traslato, attraverso i necessari adattamenti della teoria del rotore singolo al caso particolare di due rotori sincronizzati.
Come risultati si è ottenuto uno studio della potenza necessaria al volo espressa in funzione della velocità di avanzamento e di altri importanti parametri, mostrando comportamenti vicini alla letteratura. Riguardo gli sviluppi futuri, questa analisi è utilizzabile per il dimensionamento del motore elettrico necessario ad alimentare il modellino in scala ridotta.
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Mischo, Bob. "Axial turbine rotor aero-thermal blade tip performance improvement through flow control /". Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17813.
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Alemani, Mattia. "Particle emissions from car brakes : The influence of contact conditions on the pad-to-rotor interface". Doctoral thesis, KTH, Tribologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208701.
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Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale. Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissions Paper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified. Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels. Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified. Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities. Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands. Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.På grund av deras negativa hälsoeffekter har partikel emissioner reglerats i över tre årtionden. Bromsslitagepartiklar är den viktigaste icke-avgaskällan, men nuvarande kunskaper är huvudsakligen begränsade till observationsstudier. Avhandlingen syftar till att undersöka förhållandena mellan bromssystemets kontaktförhållanden och de relaterade utsläppen på modellskala. Validera resultaten på komponentnivå och förstå i vilken utsträckning de är betydande i full skala. Papper A undersöker påverkan av nominellt kontakttryck i en modellskala. Resultat visar att högre tryck motsvarar högre utsläpp. Papper B undersöker påverkan av det nominella kontakttrycket, för olika friktionsmaterial, i modellskala. En temperaturtröskel, för en emissionsökning identifieras. Papper C undersöker partikelegenskaper och slitagemekanismer för olika nominella kontakttryck, i en modellskala. Resultat visar ett förbättrat triboskikt vid högre trycknivåer. Papper D undersöker påverkan av bromssystemets förhållanden på utsläpp i en modellskala. Resultat visar att friktionskraften är den viktigaste parametern. En övergångstemperatur oberoende av kontaktförhållandet identifieras. Papper E undersöker likheter som uppträder på komponentskala och modellskala när det gäller emissioner. Resultatet visar en lovande korrelation, och möjligheten att använda en pinne-på-skiva-tribometer för FoU-aktiviteter. Papper F undersöker analogier som förekommer på en komponentskala och en modellskala, vad gäller friktionsprestanda, friktionsyta och kemisk sammansättning. Resultat visar liknande fenomen som förekommer för de två testskalorna. Papper G analyserar verkliga bromssystem arbetsförhållanden i en stadsmiljö som definierar, med hjälp av en tröghetsdyno bänk, de relaterade utsläppen. Resultatet visar utsläppsfaktorer som är förenliga med EURO6 och EURO2-reglerna, i fråga om antal respektive massa.
QC 20170808
REBRAKE Project
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Szczygielski, Wojciech Marian. "Dynamisches Verhalten eines schnell drehenden Rotors bei Anstreifvorgängen /". [S.l.] : [s.n.], 1986. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8094.
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Grudziecki, Jan. "CFD INVESTIGATION OF THE PURGE AIR INFLUENCE ON THE FLOW STRUCTURE AND BEHAVIOUR OF GAS TURBINE STAGE AND ROTOR-STATOR DISC CAVITY SYSTEM". Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174334.
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Gas turbines operate with medium of very high temperatures, which requires using advanced materials for vanes and blades and sophisticated methods of their cooling. Other parts of the turbine have to be protected from contact with hot gases. Discs that hold vanes and blades are especially exposed to this danger. In order to avoid it certain improvements have to be applied: providing sealing air and adjusting geometry of the hub to make the ingress to the cavity (space between discs)more difficult. This thesis concerns CFD investigation of the influence of the amount of sealing air on sealing efficiency and on the flow in the main annulus. The first part concerned literature study. Phenomena of ingress and interaction between main flow and sealing air were described. Different methods of estimating efficiency were shown. The second part focused only on the main path of the gas, modeling secondary air as constant and uniform outflow through the opening. The aim was to investigate how the power and reaction rate depend on the secondary air. The results were also exported to be used as boundary condition in the second part of the thesis. The last part concerned only the cavity – conditions at the main annulus were taken from the main annulus solution. Pressure in specified locations was measured and used to calculate sealing efficiency. Results were compared with the theoretical equations from the literature study. A structure of the flow inside the cavity was analyzed for several different amounts of the sealing flow. A method of unsteady flow analysis was developed and described. It was successfully implemented which proves that the method is promising. However, some improvements are necessary to obtain stable solution and research in this field should be continued.Turbopower
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Behr, Thomas. "Control of rotor tip leakage and secondary flow by casing air injection in unshrouded axial turbines /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17283.
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Haji, Zyad. "Dynamic analysis and crack detection in stationary and rotating shafts". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/dynamic-analysis-and-crack-detection-in-stationary-and-rotating-shafts(2e9dcab4-685d-4c20-8f9d-55b6892b8149).html.
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The sustainability, smooth operation and operational life of rotating machinery significantly rely on the techniques that detect the symptoms of incipient faults. Among the faults in rotating systems, the presence of a crack is one of the most dangerous faults that dramatically decreases the safety and operational life of the rotating systems, thereby leading to catastrophic failure and potential injury to personnel if it is undetected. Although many valuable techniques and models have been developed to identify a crack (or cracks) in stationary and rotating systems, finding an efficient technique (or model) that can identify a unique vibration signature of the cracked rotor is still a great challenge in this field. This is because of the unceasing necessity to develop high performance rotating machines and driving towards significant reduction of the time and cost of maintenance. Most of the crack identification techniques and models in the available literature are based on vibration-based methods. The main idea of the vibration-based method is that the presence of a crack in a rotor induces a change in the mass, damping, and stiffness of the rotor, and consequently detectable changes appear in the modal properties (natural frequencies, modal damping, and mode shapes). Among all these modal properties, the choice of the modal natural frequency change is more attractive as a tool for crack identification. The changes in natural frequencies due to a crack can be conveniently measured from just a few accessible points on the cracked rotor. Furthermore, measuring the natural frequencies does not require expensive measuring instruments, and the natural frequency data is normally less contaminated by experimental noise. However, the change that a crack induces in the natural frequencies is usually very small and can be buried in the ambient noise. Moreover, the natural frequencies are not affected if the crack is located at the nodes of modes or far from the location of inertia force and out-of-unbalance force that the disc generates in the shaft. To overcome these problems (or limitations), therefore, this study is conducted using the idea of the roving mass (roving disc in rotor case). The modal natural frequencies are used for the identification and location of cracks of various severities at different locations in both stationary and rotating shafts. The fundamental idea of the roving disc is that an extra inertia force is traversed along the cracked rotor to significantly excite the dynamics of the rotor near the crack locations. In other words, the location of a crack can be anywhere on the shaft which is contrary to the developed techniques in the available literature in which the location of a crack should be close to the disc. Along with the roving disc idea, three crack identification techniques are developed in this study using the natural frequencies of the cracked and intact shafts. Each of these techniques has its merits and limitations for crack identification. These techniques are implemented using data that are numerically generated by the finite element method based on the Bernoulli-Euler shaft elements and experimentally validated in the laboratory environment. The numerical and experimental results clearly demonstrate the capability of the suggested approach for the identification and location of cracks in stationary and rotating shafts.
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John, Marcus. "Physical properties of clusters relevant for the dust formation process in oxygen rich astrophysical environments". [S.l.] : [s.n.], 2003. http://edocs.tu-berlin.de/diss/2003/john_marcus.pdf.
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Kleiner, Julia [Verfasser], Kai-Olaf M. [Akademischer Betreuer] Hinrichsen, Kai-Olaf M. [Gutachter] Hinrichsen i Harald [Gutachter] Klein. "Reaction engineering and hydrodynamics of a rotor-stator spinning disc reactor / Julia Kleiner ; Gutachter: Kai-Olaf M. Hinrichsen, Harald Klein ; Betreuer: Kai-Olaf M. Hinrichsen". München : Universitätsbibliothek der TU München, 2019. http://d-nb.info/1195708564/34.
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Pogoryelov, Denys. "The revolving core of a biological nanomotor : structural and functional investigations on the rotor ensemble of the bacterial F₁F₀ ATP synthase /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17391.
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Inácio, Steve André Pereira. "Projecto de uma caixa de velocidades eléctrica por meio da variação do número de pólos para motores em disco de rotor em alumínio e em materiais supercondutores de alta temperatura (SAT)". Master's thesis, FCT - UNL, 2008. http://hdl.handle.net/10362/1527.
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Nesta dissertação apresenta-se um motor em disco polifásico inovador bem como uma
estratégia de controlo com base no método de variação de velocidade por comutação do
número de pares de pólos. A configuração das bobinas aliada à escolha das correntes e
tensões que se injectam nas bobinas dos estatores, permite comutar electronicamente o
número de pólos do motor entre 2, 4 6 e 8 pólos, conseguindo-se controlar a característica
binário/velocidade do motor. O motor em disco possui a bobinagem feita em cobre com dois
semi-estatores, em que quando utiliza o rotor em alumínio (com condutividade diferente de
zero) comporta-se como um motor de indução convencional. Quando se substitui o rotor em
alumínio por um constituído por um supercondutor de alta temperatura (SAT), o dispositivo
comporta-se como um motor de histerese. O princípio de funcionamento do motor em disco
convencional é baseado na indução de força electromotrizes no rotor e, consequentemente,
uma vez que o alumínio é bom condutor eléctrico, correntes eléctricas induzidas, originadas
por haver um campo magnético variável que é criado pelos semi-estatores. O comportamento
deste tipo de motores, no que diz respeito a principais características (como o
binário/velocidade para os diferentes números de pares de pólos), circuito equivalente de
Steinmetz, entre outras teorias associadas é já conhecido há bastante tempo. O princípio de
funcionamento do motor SAT é diferente do apresentado anteriormente, funciona com base
na dinâmica de vórtices e devido ao facto de aparecer o fenómeno de ancoragem de fluxo
(flux pinning) nos supercondutores de alta temperatura. Como o campo magnético varia,
então o disco roda. Este motor tem um princípio de funcionamento muito mais complexo que
o motor de indução sendo a obtenção do modelo do motor SAT complicada. A obtenção do
modelo do motor SAT não é abordado nesta dissertação.
Os comportamentos e modos de operação do motor com disco de alumínio e em
materiais SAT são simulados através de um programa comercial de elementos finitos, nesta
dissertação, sendo a supercondutividade simulada com base na relação entre o campo
eléctrico e a densidade de corrente pela lei da potenciação (E-J power law). Com as
simulações pretende-se comparar o rendimento electromecânico de ambos os motores.
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Roux, Louis. "Modélisation dynamique du départ d'une pale et de la tenue des pales suiveuses dans une turbomachine". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI056.
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Lors de la phase de certification d’un turbomoteur, le motoriste doit démontrer que la perte d’une pale de rotor ne conduit pas au "Knocking-Off", c’est à dire à la rupture en cascade des pales suiveuses. Cette démonstration est faite en général par un essai au banc coûteux car partiellement destructif. Grâce à l’amélioration des moyens de calcul, il devient possible de simuler la réponse transitoire de la structure soumise à ce type de chargement très complexe. En tant que point d’entrée sur la simulation, la connaissance du comportement des matériaux est primordiale. Or, peu d’études sont publiées sur le comportement dynamique des superalliages à base nickel monocristallins et, de surcroît, à des températures élevées de l’ordre de 1000°C. Pour prédire efficacement les conséquences d’impacts sur des pales de turbines, des travaux expérimentaux et numériques ont été réalisés sur un monocristal couramment utilisé par Turbomeca. Des essais de compression dynamique à haute température sur barres de Hopkinson permettent d’estimer le seuil de plasticité et l’écrouissage du matériau en fonction de l’orientation du cristal, de la vitesse de déformation et de la température. Les paramètres d’une loi visco-plastique anisotrope sont identifiés pour modéliser efficacement le comportement macroscopique du MC2 sous des chargements intenses et fortement multi-axiaux. Une campagne d’essais balistiques au banc de Safran Snecma a été réalisée sur des plaques et des pales monocristallines à hautes températures. Afin de prendre en compte la fragmentation des profils dans les calculs de perte de pale, un critère en déformation plastique dépendante du taux de triaxialité des contraintes est calibré puis validé par confrontation aux essais de tirs sur plaques. Des mesures de stéréo-corrélation postmortem et des enregistrements à la caméra rapide permettent de valider les simulations. Une pratique de modélisation de la perte d’une pale avec l’outil LS-Dyna a été établie et appliquée à un cas industriel de perte de pale en service. Enfin, en vue de justifier le découplage temporel entre les dommages primaires, liés aux impacts directs sur les premières pales suiveuses, et secondaires, liés aux effets de l’excentration, une approche de dynamique d’ensemble de ligne d’arbre a été développée puis validéeDuring the certification process of a turbo engine, the engine manufacturer has to demonstrate that the loss of a rotor blade does not lead to the "knocking-off" phenomenon, in other words to the cascading failure of the successive blades. Generally, this demonstration is carried out through a costly rig test driving to the partial destruction of the engine. Thanks to the improvement of computational resources, it is now possible to simulate the transient response of the structure subjected to this complex loading. The knowledge of material behavior turns out to be the essential starting point for the simulation. However, only a few studies have been published on the dynamic behavior of nickel-based single crystal superalloys at high temperature reaching 1000°C. With a view to efficiently predicting the consequences of impacts on turbine blades, experimental and numerical works have been conducted on a single crystal frequently used by Turbomeca. High-temperature dynamic compressive tests on Split Hopkinson Pressure Bars (SHPB) have enabled to estimate the material plasticity level and hardening, depending on the crystal orientation, strain rate and temperature. The parameters of a viscoplastic anisotropic law have been identified to effectively model the MC2 macroscopic behavior under highly intense and multiaxial loading. At Safran Snecma Villaroche, ballistic tests have been undertaken on both single crystal plates and blades under high temperatures. In order to consider the fragmentation of profiles in blade-off simulations, a plastic strain criterion depending on stress triaxiality has been calibrated and validated by comparison with the impacts on blades. Post-mortem digital images correlation measurements and high-speed camera recordings have confirmed these simulations. Using LS-Dyna solver, a blade-off modeling strategy has been created and applied to an actual blade-off industrial case. Finally, a rotordynamics approach has been developed and validated with the aim of separately analyzing the primary damage, caused by direct impacts on the first following blades, and the secondary damage due to the effects of unbalance on a flexible rotor
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Fidler, Tomáš. "Zatížení střechy vzdušným proudem vrtulníku při montážních pracích". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226473.
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Diploma thesis is focused on modeling rotor downwash generated by the main rotor of helicopter and analyzing its effects on the roof structure. Theoretical definition of rotor downwash flow is described in the first part of the text. Governing equations of computational fluid dynamics are briefly explained as well as boundary layer and finite volume method. Next part inquires into numerical simulation of rotor downwash based on height of rotor above the roof, shape of roof plane and climatic conditions. Results are compared with climatic load values provided by actual Czech construction standard in the end of the text.
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Jin, Xin. "Construction d'une chaîne d'outils numériques pour la conception aérodynamique de pales d'éoliennes". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0099/document.
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Ce mémoire présente les travaux réalisés en aérodynamique afin de pouvoir disposer d’une chaîne de conception complète nécessaire au traitement des différentes problématiques sur les pales éoliennes, qui ne peuvent être pris en compte à l’aide d’une méthode unique. Afin de pouvoir faire de l’optimisation de pales en fonction de différents critères, un outil numérique simplifié (VALDAG) a été développé. Le module de simulation utilise la méthode du Disque Actif Généralisé, qui s’appuie sur la résolution des équations Navier-Stokes, complété par des corrections empiriques. Il respecte un compromis entre la précision et le coût de calcul. Cet outil pour lequel une interface web a été développée pour le rendre adapté à des travaux d’ingénierie est susceptible de se calibrer automatiquement sur une nouvelle géométrie de pale grâce à la méthode Nelder-Mead Simplex. On peut ensuite réaliser une optimisation de la performance de la pale en modifiant cette géométrie, et générer les fichiers 3D qui serviront d’entrée à la simulation 3D et de visualisation des optimisations de forme. Ces designs optimisés sont ensuite validés par des simulations DNS à l’aide de l’outil NaSCar 3D développé à l’INRIA. Cet outil résout des équations Navier-Stokes sur un maillage cartésien 3D et prend en compte des obstacles immergés via la fonction Level-Set et la pénalisation. Après des adaptations sur le traitement de la géométrie de pales, un compromis de configuration CFD est trouvé pour simuler un rotor éolien. En conclusion, ce paquet d’outils VALDAG est peu coûteux, facile à utiliser et efficace. En associant VALDAG aux simulations 3D, une chaîne de conception est complétéeThis Ph.D. thesis presents some research work on aerodynamics of wind turbine blades, in order to dispose a conception chain necessary for different problems, which cannot be treated by one unique method. A simplified numerical toolkit (VALDAG) has been developed to optimize the performance of blades in different creteria. The simulation module use the Generalized Actuator Disc model, which relies on the solution of Navier-Stokes equations and completed with empiric corrections. This tool respects a reasonable compromise between model complexity and computational reliability. An automatic calibration mechanism was implemented using the Nelder-Mead Simplex algorithm. A web users interface (WUI) is also available to adapt VALDAG for industrial engineers. Optimization is then carried on by modifying the blades’ geometry parameters and the designs optimized is stocked in files which can be used for 3D simulation and/or visualization. The blade designed with VALDAG are then simulated by a 3D numerical tool to validate previous predictions. This 3D tool called NaSCar 3D is developed in INRIA and resolve Navier-Stokes equations on to a cartesian mesh, in which the immersed obstacles are considered with the Level-Set function and the penalization method. After some necessary adaptation for the treatment of blades’ geometry, a compromise on CFD configuration is found to simulate a wind turbine rotor. To conclude, this design toolkit VALDAG is low time-costly, user-friendly and efficient. Associated with 3D simulations, a conception chain has been established
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SINHA, ANKITA. "CREEP ESTIMATION OF GAS TURBINE ROTOR DISCS AT DIFFERENT AMBIENT CONDITIONS". Thesis, 2016. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15375.
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This paper discusses the usage of several creep models in combination with ANSYS MECHANICAL APDL finite element software and analytical calculations to predict creep strain in terms of axial and radial distortion for the typical gas turbine rotor disc model. Creep analysis of gas turbine disc using different creep models at offset design condition is the main consideration of this work.
For many components of industrial gas turbine, the design for creep is conservative because of close control of dimensions required over the life, the maintenance of critical dimensions, such as clearance between rotating and static parts. Components operate for extensive periods of time under heavy loads in conditions of non-uniform temperature which go up to 5350C during the process. The stress-strain state also changes over time due to creep phenomena. These conditions make difficult to simulate the actual body by other means like finite element analysis; it is essential to establish creep properties over all ranges of temperatures, stresses and durations of time for the reliable prediction of creep deformation and stress rupture in gas turbine components.
A typical gas turbine disc model is used in this present study to investigate the relationship between operating conditions and design parameters on the creep phenomena. Several ANSYS creep mathematical models are investigated to use for perfect fitting according to the conditions and available data. Time hardening and strain hardening creep model is further studied to analyze the creep of disk. While doing creep analysis, ambient temperature is set to standard 320C. But this standard process is not valid for every site of world so a different procedure has been set up to simulate the offset design conditions to capture site specific creep issues. Results show variations in axial and radial creep strain with respect to analysis done at constant average temperature for 160k hours. A good agreement is also found between the results obtained in this current study and the results available in the literature for strain hardening and time hardening model. It is found that stress relaxation after 160K hour using time hardening model is more than using strain hardening. Analysis with offset design condition shows that to capture the clearance correctly and more realistically, offset design condition needs to be simulated. Present work concludes that further study is required in the area of creep mathematical model and validation of simulated results with experimental data.
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Blignaut, Gert. "Dynamic modelling of a bolted disc rotor assembly". Thesis, 2008. http://hdl.handle.net/10352/281.
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M. Tech. (Department of Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of TechnologyA project investigating the behaviour of an assembled preloaded rotor was performed for an M-Tech qualification in the Mechanical Engineering Department. Pre-Stressing of mechanical structures is widely applied to improve their performance, and in this project the behaviour of an assembled preloaded rotor was investigated. An Impact Test was done on the structure to see if induced stresses originated by a set of bolts which keep the discs system together, would influence the natural dynamic response or the rotor. Tendencies in the natural response were investigated. Analytical models like the Finite Element Beam model and the Solid Finite Element model were studied in order to find a represntative description of this particular structure's dynamic behaviour after pre-tension. From the experimental results it was apparent that the slenderness of the pre-tensioned sector influences the natural frequency. The solid finite element model appears to be the most applicable model to present the assembled rotor-disk system as a continuous shaft. Furthermore, modelling and predictions for a typical rotor and similar assembled structures can be generated from the findings.
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Maurya, Gaurav. "Analysis of gyroscopic effects in rotor disc systems". Thesis, 2013. http://ethesis.nitrkl.ac.in/4686/1/211ME1160.pdf.
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This work deals with study of dynamics of a viscoelastic rotor shaft system, where Stability Limit of Spin Speed (SLS) and Unbalance Response amplitude (UBR) are two indices. The Rotor Internal Damping in the system introduces rotary dissipative forces which are tangential to the rotor orbit, well known to cause instability after certain spin speed. There are two major problems in rotor operation, namely high transverse vibration response at resonance and instability due to internal damping. The gyroscopic stiffening effect has some influence on the stability. The gyroscopic effect on the disc depends on the disc dimensions and disc positions on the rotor. The dynamic performance of the rotor shaft system is enhanced with the help of gyroscopic stiffening effect by optimizing the various disc parameters (viz. disc position and disc dimension). This optimization problem can be formulated using Linear Matrix Inequalities (LMI) technique. The LMI defines a convex constraint on a variable which makes an optimization problem involving the minimization or maximization of a performance function belong to the class of convex optimization problems and these can incorporate design parameter constraints efficiently. The unbalance response of the system can be treated with H¡Þ norm together with parameterization of system matrices. The system matrices in the equation of motion here are obtained after discretizing the continuum by beam finite element. The constitutive relationship for the damped beam element is written by assuming a Kelvin ¨C Voigt model and is used to obtain the equation of motion. A numerical example of a viscoelastic rotor is shown to demonstrate the effectiveness of the proposed technique.
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Wallis, Lisa M. "A comparison of bi-directional disc brake rotor passage designs /". 2003. http://www.library.unsw.edu.au/~thesis/adt-NUN/public/adt-NUN20040913.123436/index.html.
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WEI, YU-JEN, i 魏裕仁. "Numerical Study on Aerodynamic Interaction and Aeroacoustics Characteristics between Rotor Disks of Coaxial Helicopter". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/96653247005440445244.
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碩士逢甲大學
航太與系統工程學系
105
Compared with another type of helicopters, the coaxial rotor has the advantages of greater lift capacity, higher maneuverability and more compact. Thus, it is allowed to operate in places where others cannot. Consequently, this study conducts numerical analysis to learn the aerodynamic and aeroacoustics characteristics of the coaxial rotor in more detail and then the simulated results are validated with the experimental acoustic data. In this research, the aerodynamics characteristics of a single rotor, coaxial rotor and coaxial rotor with fuselage are analyzed and the simulated results show that the coaxial rotor performs the higher lift and the existence of fuselage causes some reduction of lift. It was found that the lift increases linearly to a saturated value with increasing pitch angle. As the spacing increases, the lift of the upper rotor increases gradually, and the lower rotor also increases to a peak value and then drops rapidly which lowers the total lift. By observing the vorticity field, it can be found that the stronger vortices resulting from the rotor interactions, higher level noise to be produced. Consequently, as the rotational speed increases, the noise level increases linearly while the lift increases curvilinearly. Under the same conditions, the rotor blades with symmetric section perform higher lift and lower noise level than the asymmetric one. The noise level can be further reduced to have the tip of rotor blade swept back while still keeping the lift. In addition, adding a fillet to the above-mentioned swept rotor blade can alleviate the noise further. According to the analysis, asymmetric rotor blade with sweep angle and fillet is recommended for the coaxial rotor of heavy-payload and low-noise requirement.
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Tai, Shih-Wen, i 戴士文. "Thermal Analysis of Vented Rotors in Automotive Disc-Brake System". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/02974284561377052116.
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碩士國立高雄應用科技大學
模具工程系
98
Ventilated rotors are used in most automotive disc brake. More cooling surface area is achieved by the setup of vanes. Several different designs of the internally vented rotors have been invented to enhance the pumping action for airflow so as to increase the heat convective coefficient. In this study, we intended to analyze the effect of the vents through temperature evolution and heat transfer in the vented disks. A model on the basis of COMSOL multiphysics was proposed for simulation, with the aid of MATLAB coding. In order to treat the dynamic thermal contact problem occurred at the contact surface of the disk and pad, an ALE mode is added to the convection and conduction heat transfer mode in COMSOL. At any instant of time, heat generation due to frictional sliding at the contact surface is distributed to the disk and pad. According to Limpert's formula, the percentage of heat absorbed by the disk is approximately 82% to 88% of the total heat, depending on the thermal properties of the disk and pad. The results obtained from COMSOL model reveal a larger proportion for disc, about 95% to 97%. A simplified model is thus created, with a specified ratio of heat input to the disk, only heat transfer in the disk is considered. In the present work four kinds of disks were investigated, including a solid disk, a straight radial vane rotor, a sloped vane rotor, and a rotor with diamond and teardrop pillars. There are two brake conditions to be investigated: they are emergency-stop braking and constant-load braking. It is found that the maximum temperature of vanes rotors is much less than that of a solid disk in constant-load braking process. On the other hand, no obvious differences were observed for different types of vanes. Keywords: disk brake, ventilated rotor, heat transfer for frictional sliding, COMSOL, ALE
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Oliveira, Marco David Canário de. "Estudo analítico, concepção e ensaio experimental de uma bomba de discos para baixo número de Reynolds". Master's thesis, 2009. http://hdl.handle.net/10400.6/3561.
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Este trabalho tem como objectivo projectar, e construir, uma instalação experimental que permita analisar, e estudar, o comportamento de uma bomba de discos para baixo número de Reynolds. O trabalho divide-se em quatro partes distintas. Apesar da pouca investigação encontrada para este tipo de turbomáquinas, numa primeira parte é feita uma revisão ao estado da arte sobre as mesmas. Referem-se em geral os trabalhos sobres as turbomáquinas que têm por base de funcionamento as tensões viscosas. Neste contexto avaliam-se os estudos mais importantes na área da modelação analítica, experimental e numérica. Dá-se uma maior importância aos estudos mais recentes, avaliando também os estudos mais antigos, que foram pioneiros na sua época. Numa segunda parte são apresentadas várias aproximações para o estudo do escoamento num disco em rotação, bem como os modelos físico-matemáticos de uma bomba de discos. Este estudo permitiu deduzir equações para projectar a bomba de discos. É ainda apresentado, em detalhe, o desenvolvimento de uma instalação experimental de raiz, caracterizando em pormenor os problemas e conceitos desenvolvidos, tanto para bomba de discos como para toda a instrumentação necessária ao ensaio. É também apresentado o procedimento experimental utilizado para colher os resultados dos ensaios. Finalmente é feita uma análise aos resultados e é analisada a extrapolação de resultados com base em vários grupos adimensionais. O estudo efectuado usando os vários grupos adimensionais permite concluir que existem erros significativos associados à utilização de grupos adimensionais convencionais em turbinas de disco. Conclui-se que a única forma fidedigna de obter resultados é o ensaio de bombas de disco à escala real, quer esta modelação seja feita experimental ou numeri amente. É ainda verificada a concordância entre as variáveis de desempenho experimentais e as obtidas de forma analítica. Os resultados apresentam uma boa concordância, dentro das limitações das incertezas experimentais e das hipóteses subjacentes ao modelo analítico.
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Inácio, David Duarte Pereira. "Estudo do motor em disco com o rotor em alumínio e em supercondutor multi-semente". Doctoral thesis, 2014. http://hdl.handle.net/10362/14386.
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Nesta dissertação é realizado o estudo de um motor em disco polifásico com armadura
convencional e rotor que pode ser convencional, em alumínio, ou composto por material
supercondutor de alta temperatura multi‐semente.
O motor com o rotor em alumínio apresenta um comportamento assíncrono bem
definido, baseado na lei geral de indução de eletromotrizes no induzido. Contudo, ao ser
mergulhado em azoto líquido, evidencia melhores características eléctricas, tanto do
induzido como do indutor, mesmo que o núcleo ferromagnético convencional possa exibir
degradação magnética.
O motor com o rotor SAT exibe um comportamento distinto, evidenciando ambos os
regimes síncrono e assíncrono estáveis. O regime síncrono fica caracterizado pelo fenómeno
de aprisionamento de campo, que garante que o rotor gire síncrono com o campo girante do
estator. Em regime assíncrono, para um determinado valor de binário resistente aplicado
superior ao electromagnético máximo desenvolvido pelo motor, o fenómeno de escoamento
de campo está presente, sendo o binário electromagnético motor reforçado por um binário
extra de perdas de carácter resistivo desenvolvidas no rotor devido à interacção da
densidade de corrente a campos eléctricos que se estabelecem no rotor. Neste caso, o
fenómeno de escoamento de campo não é devido a forças de Lorentz que se definem na
matriz de Abrikosov, mas sim devido a esta ser “puxada” pelo campo girante do estator,
ficando a matriz a deslizar sobre o rotor.
De modo a obter as características dos sistemas electromecânicos em estudo é
realizada uma análise teórica, baseada na teoria convencional das máquinas eléctricas, com
o objectivo de compreender alguns dos fenómenos do motor de fluxo axial, e uma análise
baseada num programa comercial de elementos finitos onde o fenómeno da
supercondutividade é simulado com base na relação entre o campo elétrico e a densidade de
corrente pela lei da potenciação (E‐J power law). O ensaio dos motores referidos é realizado
para comparar ambos os sistemas e de realçar o princípio de funcionamento e as
características mais relevantes de cada um.
Da análise realizada é desenvolvido um modelo que caracteriza o funcionamento da
máquina com o rotor com SAT.Fundação para a Ciência e a Tecnologia (FCT) - (SFRH / BD / 43464 / 2008)
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Wu, Wen-Juan, i 吳文娟. "New Disc Motor using Frequency of Rotating Magnetic Field Vector Independent of Rotor Speed Control". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/e82t33.
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43
Chen, Chun-Yang, i 陳俊揚. "Life assessment of the disc rim of low pressure steam turbine rotors". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/63625694984769077857.
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Kao, Fu-Tsuen, i 高福村. "Finite Element Model Updating and Thermal Analysis of Ventilated Disc-Brake Rotors". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/50875693908809145251.
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碩士東南科技大學
機械工程研究所
103
In most finite element studies, the finite element models are not verified but assumed to be correct. This assumption should be substantiated before conducting further finite element simulations. To achieve this purpose, the FE model updating technique can be adopted to correlate the FE analysis result to the experiment. In this research, experimental modal testing and finite element analysis on a ventilated disc-brake rotor were first performed, and then based on the test frequencies and mode shapes, FE model updating was carried out using geometric and material parameters as the updating parameters. The resulted FE models are capable of accurately predicting the dynamic behaviors of the disc-brake rotor and suitable for further design modification studies. For the thermal analysis, heat transfer coefficients on the surfaces of a rotor as functions of time are first estimated by CFD simulation, and then imported to a thermal analysis program as the boundary condition. Finally, the temperature distribution of the rotor can be calculated by finite element analysis. The simulation results show that vortices will arise in the vented passages of straight-vent rotors, which means less heat carried away and lower heat transfer coefficients. To implement thermal analysis on the rotor block using ANSYS Transient Thermal, to get the maximum temperature histories for the brake rotors.
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Erickson, Ryan David. "Experimental investigation of disc cavity leakage flow and hub endwall contouring in a linear rotor cascade/". Diss., 2010. http://purl.umn.edu/90852.
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