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1
Tingey, Samuel Egnew. "Discharge Coefficients of Oblique Weirs." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1010.
Повний текст джерелаАнотація:
Oblique weirs are those weirs placed at an angle with respect to the channel centerline. They can be used in canal applications where more discharge is needed, but there is limited freeboard. The discharge coefficients were determined for 54 different weirs by measuring total head for various flows over each weir. These weirs included sharp, half round and quarter-round-crested weirs. There were 18 weirs for each crest shape with three weir heights for each angle tested. The oblique angles tested were 10°, 15°, 25°, 45°, 60°, and 90° with respect to the channel centerline, with the nominal weir heights being 4, 8, and 12 inches. The half-round-crested weirs were the most efficient, followed by the quarter-round-crested weirs and the sharp-crested weirs were the least efficient. By decreasing the oblique angle, the weir length became longer and the weir would be more efficient than the normal weir.
2
Kinsman, Roger Gordon. "Outlet discharge coefficients of ventilation ducts." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59271.
Повний текст джерелаАнотація:
Discharge coefficients are an important parameter in the prediction of the air displacement performance of ventilation outlets and in the design of ventilation ducts.Discharge coefficients of a wooden ventilation duct 8.54 metres in length and of a constant 0.17 m$ sp2$ cross sectional area were measured. Four different outlet shapes and 3 aperture ratios of each shape were tested. A split plot experimental design was used to evaluate the effect of outlet shape, outlet size, and distance from the fan on discharge coefficient. The relationship between duct performance characteristics and discharge coefficient was examined. A mathematical equation to predict the discharge coefficient was developed and tested.
Discharge coefficient values measured ranged from 0.19 to 1.25 depending on the aperture ratio and distance from the fan. Outlet shape had no significant effect. The apparent effects of aperture ratio and size are due to the effects of head ratio. The equation predicting the discharge coefficient had a maximum error of 5 percent for the aperture ratios of 0.5 and 1.0, and 15 percent at an aperture ratio of 1.5.
3
Yip, C. W. H. "Compressible discharge coefficients of branching flows." Thesis, University of Aberdeen, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233007.
Повний текст джерелаАнотація:
A two-dimensional numerical model for compressible branching flow through a slot is described for the purpose of predicting the discharge coefficients of film cooling holes in gas turbine blades. The method employs free-streamline theory and the hodograph transformation. It calculates the area ratio of hole to duct and the contraction coefficient from a set of prescribed boundary conditions. An approximate method for calculating the compressible contraction coefficients is also discussed in the thesis. It employs the incompressible theory previously developed by McNown and Hsu (1951) for the free efflux, the 'compressibility factor' and the flow parameter (Po-Pj)/(Po-P1), where Po, Pj, P1 represent the stagnation pressure, the static pressure of the jet and the static pressure of the approach flow, respectively. The advantages of using this method are the direct input of the area ratio of hole to duct and its speed of calculation. Experimental tests were performed using a specially designed rig in a supersonic wind tunnel. The investigations included sharp-edged slots with three different widths, a single hole and a row of two holes. The approach velocity in terms of the characteristic Mach number ranged from 0.18 to 0.58 and the pressure ratio Po/Pj, ranged from 1.10 to 1.97. Agreement between the experimental data and the theoretical values was good to within the experimental accuracy (typically around +/- 5%) for the slots and the 2-hole configuration. For the 1-hole configuration, less bleed flow than predicted was observed, with the discrepancy varying from 7% to 18%. The latter case is a very severe test of a purely two-dimensional theory. The results for the 2-hole plate suggest that the slot theory can in fact be used to predict the flow through a row of holes with small pitch to diameter ratios.
4
Rowbury, David. "Discharge coefficients of nozzle guide vane film cooling holes." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365838.
Повний текст джерела
5
Gault, R. I. "Alternative methods for determining coefficients of discharge for engine simulation." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273271.
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6
Beauchemin, Melanie. "Investigations of nozzle discharge coefficients in a compliant air bearing system." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ45870.pdf.
Повний текст джерела
7
Ntamba, Ntamba Butteur Mulumba. "Non-Newtonian pressure loss and discharge coefficients for short square-edged orifices plates." Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1252.
Повний текст джерелаАнотація:
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011.Despite the extensive research work carried out on flow through short square-edged orifice plates over the last century (e.g. Johansen, 1930; Benedict, 1977; Alvi et al., 1978; Swamee, 2005; ESDU, 2007), gaps in the engineering data still exist for certain ranges of flow conditions and geometries. The majority of data available in the literature are for Newtonian fluids in the turbulent flow regime (ESDU, 2007). Insufficient data have been observed for the orifice with pipe diameter ratio, β = 0.2, in the laminar flow regime. There are no experimental data for β = 0.3 and 0.57. The objective of this thesis was to conduct wide-ranging experimental studies of the flow in orifice plates, which included those geometrical configurations, by measuring pressure loss coefficients and discharge coefficients across the orifice plates using both Newtonian fluids and non-Newtonian fluids in both laminar and turbulent flow regimes. The test work was conducted on the valve test rig at the Cape Peninsula University of Technology. Four classical circular short square-edged orifice plates having, β = 0.2, 0.3, 0.57 and 0.7, were tested. In addition, two generation 0 Von Koch orifice plates (Von Koch, 1904), with equivalent cross sectional area were also tested for β = 0.57. Water was used as Newtonian fluid to obtain turbulent regime data and also for calibration purposes to ensure measurement accuracy and carboxymethyl cellulose, bentonite and kaolin slurries were used at different concentrations to obtain laminar and transitional loss coefficient data. The hydraulic grade line method was used to evaluate pressure loss coefficients (Edwards et al., 1985), while the flange tap arrangement method was used to determine the discharge coefficients (ESDU, 2007). A tube viscometer with three different pipe diameters was used to obtain the rheological properties of the fluids. The results for each test are presented in the form of pressure loss coefficient (kor) and discharge coefficient (Cd) against pipe Reynolds number (Re)
8
Devkota, Jay P. "Variation of Manning’s Roughness Coefficient with Diameter, Discharge, Slope and Depth in Partially Filled HDPE Culverts." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1340991250.
Повний текст джерела
9
Yendodu, Vishnu Vardhan Reddy. "A comprehensive database on air plasma kinetics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25762/.
Повний текст джерелаАнотація:
The kinetic models described in this thesis are of great importance because they can be used to understand the chemical phenomena induced by electrical discharges in air. Experimental data obtained by the research group in the Physics Department of the University Milano Bicocca are compared with the numerical results. The study highlighted how the initial ozone formation is inhibited and cancelled by nitrogen oxidation processes.
In this thesis, a comprehensive database on Air Plasma Kinetic reactions with rate coefficients is presented. The database were built from Park Model and Sakiyama Model. In both models, the references to rate coefficients vary from the real material, and not all the rate coefficients satisfy the references. The database built is made ready for implementation on ZDPlasKin software.
10
Johnson, Michael Clyde. "Discharge Coefficient Scale Effects Analysis for Weirs." DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/7604.
Повний текст джерелаАнотація:
Much work has been published regarding discharge coefficients for various weir structures. What has not been published to the same extent are the effects of model scale associated with the weirs being studied. If laboratory weirs are too small, scale effects can affect the magnitude of the discharge coefficient. These errors may be significant if the weir serves as a control structure for an emergency spillway. It is imperative that discharge be accurately predicted to enable safe design and operation.
Numerical and physical means were employed to analyze the effects of scale associated with Froude Modeling of weirs with sharp and flat crests. An inverse formulation for the ideal flow of water over a weir was developed. The formulation appeared to be sound; however, the numerical method failed because the boundary condition on the free surface had multiple roots, which were almost equal in magnitude and sign.
Laboratory data were collected and analyzed to determine the existence of scale effects and the flow conditions under which they were manifested. Results indicate that scale effects are present even with relatively large model sizes (12 inches high with a crest thickness of 24 inches). The scale effects appear to be associated with the size of the weir-wall and the viscosity. Although the viscosity was not altered, the results show a characteristic Reynolds Number for a given crest thickness-to-height ratio where scale effects cease to exist for increasing total head.
Several graphs defining the conditions where scale effects exist for a given weir size were developed. Use of the graphs allows one to determine the minimum total head (piezometric plus velocity head) that one may operate a given size of weir or size a weir given the minimum total head to be tested to avoid scale effects.
A design curve for discharge coefficients was developed to be used for determining the capacity of prototype weirs. The curve can be used to determine the discharge coefficient for new or existing hydraulic control structures.
11
Prohaska, Paul D. "Investigation of the discharge coefficient for circular orifices in riser pipes." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1219852241/.
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12
Khaldi, A. "Discharge coefficient of film cooling holes with rounded entries or exits." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378758.
Повний текст джерела
13
Solis, Suraye Rori. "Estimating Flow Through Rock Weirs." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90401.
Повний текст джерелаАнотація:
Rock weirs are small dam-like structures composed of large loose rock commonly found in ecological engineering design. By appearing more natural than concrete structures, rock weirs are preferred for use as hydraulic control structures in river engineering, stormwater management, and constructed wetlands. Rock weirs increase hydraulic head upstream, and facilitate fish passage, channel stabilization, floodplain reconnection, and in-stream habitat creation. When used in constructed wetlands, rock weirs play a valuable role in developing appropriate wetland hydrology. Although rock weirs are commonly used, a deficit of knowledge exists relating to the stage-discharge relationship of these structures. Therefore, the goal of this research was to determine a weir equation and corresponding discharge coefficients that improve predictions of flow through rock weirs.
A flume study was conducted to develop a rock weir equation and discharge coefficients. Scaled model rock weirs were tested in a 1 m x 8 m x 0.4 m recirculating flume. Rock weirs varied by length (0.152 m, 0.305 m, and 0.457 m), depth (0.152 m and 0.305 m), and minimum rock diameter (12.7 mm, 19.1 mm, 25.4 mm). Three channel slopes were used (0%, 0.5%, 1%), and the flume discharge was varied for five water stages for each rock weir. Buckingham Pi analysis was used to develop seven dimensionless parameters. Regression analyses were then used to develop a model for discharge and the discharge coefficient. Results showed that weir length and depth play a significant role in predicting the discharge coefficient of rock weirs.Master of Science
Rock weirs are small dam-like structures composed of large loose rock; by appearing more natural, they are preferred for use in river engineering, stormwater management, and constructed wetlands. Rock weirs increase upstream water depth, improving fish passage, channel stabilization, floodplain reconnection, and in-stream habitat creation. When used in design of constructed wetlands, rock weirs are used to establish the necessary water depths for a given type of wetland. Although rock weirs are commonly used in engineering design, there are no equations to predict water velocity or flow rate across these structures. Therefore, the goal of this research was to determine a weir equation that improves predictions of flow through rock weirs. A flume study was conducted to develop a rock weir equation. Miniature rock weirs were tested in a 1 m x 8 m x 0.4 m recirculating laboratory channel. Rock weirs varied by length (0.152 m, 0.305 m, and 0.457 m), depth (0.152 m and 0.305 m), and minimum rock diameter (12.7 mm, 19.1 mm, 25.4 mm). Three channel slopes were used (0%, 0.5%, 1%), and the water flow rate was varied for five water depths for each rock weir. Statistical analyses were conducted to determine an equation that predicts water flow through rock weirs for use in engineering design. Results showed that weir length and depth played a significant role in predicting water flow through rock weirs.
14
Stevenson, Philip Mark. "A study of factors affecting the coefficient of discharge of twinned poppet-valves." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314165.
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15
Kim, Namgyun. "Numerical Study on Debris Flow Behavior with Two Sabo Dams." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200499.
Повний текст джерела
16
Linfield, Kevin William. "A study of the discharge coefficient of jets from angled slots and conical orifices." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0028/NQ49816.pdf.
Повний текст джерела
17
Ongkodjojo, Ong Andojo. "Electrohydrodynamic Microfabricated Ionic Wind Pumps for Electronics Cooling Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1354638816.
Повний текст джерела
18
Cobanoglu, Ismail. "Experimental Study Of Single And Multiple Outlets Behavior Under Constant Head." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12610123/index.pdf.
Повний текст джерелаАнотація:
The performance of outlets under constant head is investigated in this study. Behavior of single outlet is analyzedsubsequently effect of multiple outlets on a single outlet is examined. Parameters taken into account are constant head of water, orifice shape, orifice length, number of open outlets and discharge. The outlet type, which is examined, can be classified as a short tube orifice. Two different orifice diameters and tube lengths are used. Outlets had the diameter, 6.00 and 10.35mm. The ratio of orifice length to diameter (l/d) was 5 and 8. Number of outlets is 5, which are opened in several combinations. A dimensional analysis shows that discharge coefficient, Cd is a function of diameter-length ratio and the Reynolds Number. In this study, high Reynolds Number (2300<
Re<
18600) range is examined and the results are compared with the available data in the literature. Furthermore, performance of the group outlets is investigated.
19
Carlsson, Per. "Flow Through a Throttle Body : A Comparative Study of Heat Transfer, Wall Surface Roughness and Discharge Coefficient." Thesis, Linköping University, Department of Management and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8378.
Повний текст джерелаАнотація:
When designing a new fuel management system for a spark ignition engine the amount of air that is fed to the cylinders is highly important. A tool that is being used to improve the performance and reduce emission levels is engine modeling were a fuel management system can be tested and designed in a computer environment thus saving valuable setup time in an engine test cell. One important part of the modeling is the throttle which regulates the air. The current isentropic model has been investigated in this report. A throttle body and intake manifold has been simulated using Computational Fluid Dynamics (CFD) and the influence of surface heating and surface wall roughness has been calculated. A method to calculate the effective flow area has been constructed and tested by simulating at two different throttle plate angles and several pressure ratios across the throttle plate. The results show that both surface wall roughness and wall heating will reduce the mass flow rate compared to a smooth and adiabatic wall respectively. The reduction is both dependent on pressure ratio and throttle plate angle. The effective area has showed to follow the same behaviour as the mass flow rate for the larger simulated throttle plate angle 31 degrees, i.e. an increase as the pressure drop over the throttle plate becomes larger. At the smaller throttle plate angle 21 degrees, the behaviour is completely different and a reduction of the effective area can be seen for the highest pressure drop where a increase is expected.
När ett nytt bränslesystem ska designas till en bensinmotor är det viktigt att veta hur stor mängd luft som hamnar i cylindrarna. Ett verktyg som är på frammarsch för att förbättra prestanda och minska emissioner är modellbaserad simulering. Med hjälp av detta kan ett bränslesystem designas och testas i datormiljö och därigenom spara dyrbar tid som annars måste tillbringas i en motortestcell. En viktig del av denna modellering är spjället eller trotteln vilken reglerar luften. I denna rapport har studier gjort på den nuvarande isentropiska modellen. Ett spjällhus och insugsgrenrör har simulerats med hjälp av Computational Fluid Dynamics (CFD) och påverkan av värme samt ytjämnhet på väggen har beräknats. En metod att beräkna den effektiva genomströmmade arean har konstruerats och testats vid två olika spjällvinklar samt flertalet tryckkvoter över spjället. Resultaten visar att både en uppvärmd vägg och en vägg med skrovlighet kommer att minska massflödet jämfört med en adiabatisk respektive en slät vägg. Minskningen har både spjällvinkel samt tryckkvots beroende. Den effektiva genomströmmade arean har visats sig följa samma beteende som massflödet vid den större simulerade spjällvinkeln 31 grader, det vill säga öka med ökat tryckfall över spjället. Vid den mindre vinkeln 21 grader, är beteendet helt annorlunda jämfört med massflödet och en minskning av den effektiva arean kan ses vid det största tryckfallet där en ökning förväntades.
20
Zuniga, Humberto. "Study of Discharge Coefficient and Trends in Film Cooling Effectiveness of Conical Holes with Increasing Diffusion Angles." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3578.
Повний текст джерелаАнотація:
Previous studies indicate that increasing the diffusion angle in conical film-cooling holes leads to an improvement in their film cooling effectiveness. Discharge coefficient and film cooling effectiveness measurements are conducted to characterize this behavior. Part of the focus of this investigation is to find out how this trend develops and attempt to ascertain the optimum cone angle, if possible. Six test plates, each with one row of eight conical-shaped cooling holes of equal diffusion angles of 0, 1, 2, 3, 6, or 8 [degrees], with respect to the hole axis are used in this study. The ratios of the hole exit areas to the inlet areas range from 1 to 2.85. Coolant injection angle for all holes is at 35 degrees to the horizontal, in the direction of the main flow. Coefficients of discharge of all holes are reported under flow conditions. Temperature sensitive paint, TSP, is the technique used to find the temperature distribution downstream of the cooling holes and determine the laterally averaged film-cooling effectiveness. Data are obtained for blowing ratios ranging from 0.5 to 1.5, at a constant density ratio of 1.26. Results and trends are compared with established literature, which also recommends that a cylindrical entry length for diffused holes should be at least 4 diameters long. The effect that an added entry length has on the 3-degree conical plate's cooling effectiveness is also explored. Data are compared to baseline cylindrical holes, as well as to fan-shaped film holes found in open literature. Results indicate that the conical holes with larger diffusion angles provide strikingly even film protection and outperform fan shaped and cylindrical holes under certain conditions over extended downstream distances. Also, the addition of a cylindrical entry length to a conical hole, by providing a manageable metering diameter, should ease their usage while providing the full benefits of the conical geometry which may one day lead to numerous industrial applications.M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
21
Hollingshead, Colter L. "Discharge Coefficient Performance of Venturi, Standard Concentric Orifice Plate, V-Cone, and Wedge Flow Meters at Small Reynolds Numbers." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/869.
Повний текст джерелаАнотація:
The relationship between the Reynolds number (Re) and discharge coefficients (C) was investigated through differential pressure flow meters. The focus of the study was directed toward very small Reynolds numbers commonly associated with pipeline transportation of viscous fluids. There is currently a relatively small amount of research that has been performed in this area for the Venturi, standard orifice plate, V-cone, and wedge flow meters. The Computational Fluid Dynamics (CFD) program FLUENT© was used to perform the research, while GAMBIT© was used as the preprocessing tool for the flow meter models created. Heavy oil and water were used separately as the two flowing fluids to obtain a wide range of Reynolds numbers with high precision. Multiple models were used with varying characteristics, such as pipe size and meter geometry, to obtain a better understanding of the C vs. Re relationship. All of the simulated numerical models were compared to physical data to determine the accuracy of the models. The study indicates that the various discharge coefficients decrease rapidly as the Reynolds number approaches 1 for each of the flow meters; however, the Reynolds number range in which the discharge coefficients were constant varied with meter design. The standard orifice plate does not follow the general trend in the discharge coefficient curve that the other flow meters do; instead as the Re decreases, the C value increases to a maximum before sharply dropping off. Several graphs demonstrating the varying relationships and outcomes are presented. The primary focus of this research was to obtain further understanding of discharge coefficient performance versus Reynolds number for differential producing flow meters at very small Reynolds numbers.
22
Ondrejka, Adam. "Analýza obtokového kanálu turbodmychadla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231830.
Повний текст джерелаАнотація:
The aim of master’s thesis was to put forward calculation methodology of wastegate turbocharger bypass channel discharge coefficient. Designed methodology was based on discharge coefficient analysis conducted utilizing CFD simulations of turbocharger turbine-side parametric model. It was achieved to propose a calculation, which differentiates relatively in average 1,4% from CFD data. New methodology improves the accuracy bypass channel design and helps to choose appropriate wastegate valve actuator.
23
Cóstola, Daniel. "Ventilação por ação do vento no edifício: procedimentos para quantificação." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/16/16132/tde-26102010-144530/.
Повний текст джерелаАнотація:
Este trabalho tem por objetivo formular um procedimento para a quantificação da vazão do ar promovida pela ação do vento no interior do edifício, em climas quentes. O procedimento é dividido em cinco partes: obtenção dos dados de vento, transposição dos dados de vento da estação meteorológica para a área de interesse, determinação dos coeficientes de pressão no edifício, determinação dos coeficientes de descarga das aberturas, e o cálculo da vazão no interior do edifício. Diversas ferramentas são apresentadas para a execução de cada etapa, e seu uso e parâmetros de entrada são discutidos. O uso de túnel de vento e a simulação com ferramentas de dinâmica dos fluidos computacional são apresentados em detalhes. O trabalho conclui que estão disponíveis aos projetistas um amplo conjunto de ferramentas para a predição da ventilação natural no interior do edifício, e que somente pelo seu uso criterioso, as conclusões são passiveis de uso no projeto arquitetônico.The aim of this dissertation is to produce a procedure for wind-driven natural ventilation prediction, in hot climate building. The procedure is organized in five parts: wind data obtaining, topographic e roughness correction, pressure coefficient determination, discharge coefficient determination, and flow rate calculation inside the building. The dissertation presents some tools to execute each part of the procedure, and the specificities of those tools are discussed. Wind tunnel experiment and computation fluid dynamic simulation are presented in detail. The research conclusion is that designers have many tools avaliable to performe a natural ventilation prediction, but just concient use will produce reliable results for architectural design.
24
Jansa, Jakub. "Stochastická předpověď průměrných měsíčních průtoku ve vybraném vodoměrném profilu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240072.
Повний текст джерелаАнотація:
The diploma thesis is focused on the average monthly flows forecast in the selected hydrometric profile. Aim of this work will be evaluation of the calculated values and the interpretation of the results in understandable form. The next step will be find an appropriate connection between randomly-generated inputs in the form of random real flow series using the standard hydrological prediction models. This models are based on the principles of artificial intelligence and probability model. The result of the work will be verification of procedures and compilation of mean monthly flow stochastic forecast in selected hydrometric profile, which would be used for a reservoirs management, respectively for water systems management.
25
BARTOLUCCI, MICHELE. "Proposta di una nuova metodologia su base fenologica per la valutazione del bilancio idrogeologico giornaliero di bacino: calibrazione e validazione del modello attraverso misure sperimentali nel medio e alto bacino del Fiume Metauro." Doctoral thesis, Urbino, 2018. http://hdl.handle.net/11576/2656912.
Повний текст джерелаАнотація:
Il lavoro di ricerca e applicativo svolto durante il dottorato è stato mirato alla ideazione, allo sviluppo, alla calibrazione e alla validazione di un modello che consentisse di calcolare, a scala temporale giornaliera, il bilancio idrogeologico a livello di bacino con una maggior accuratezza rispetto a quella che si riesce a raggiungere con gli attuali modelli. A tal fine si è estesa a livello di bacino la procedura correntemente utilizzata in agricoltura per il dosaggio dell’acqua di irrigazione, procedura che impiega dei coefficienti colturali (Kc) per correggere la evapotraspirazione potenziale stimata con l’equazione di Penman Monteith; in particolare si è calcolato un coefficiente colturale unico giornaliero di bacino che è la media pesata di tutti i coefficienti colturali delle varie classi di uso del suolo, coefficienti che variano durante l’anno secondo le fasi fenologiche delle colture (iniziale, sviluppo, intermedia, finale). Il quaderno FAO n°56 (Allen et al., 1998) è stato la fonte primaria dei valori dei Kc e delle durate delle fasi fenologiche ma si è resa necessaria un’attività di ricerca per trovare i rispettivi valori per le aree non agricole. Il modello ha previsto un’ulteriore correzione della evapotraspirazione potenziale che tenesse conto della superficie reale del territorio attraverso il coefficiente di acclività (pari al rapporto tra superficie reale e proiettata); anche i valori di precipitazione sono stati corretti ma mediante l’inverso del coefficiente d’acclività; il calcolo del runoff è stato ottenuto mediante il metodo del curve number (USDA, 1972) adattato per la modellazione in continuo (Williams, 2000); infine è stato realizzato un bilancio idrico del suolo che ha consentito attraverso vari parametri di stimare a scala giornaliera le 3 incognite del bilancio, ovvero la evapotraspirazione reale, la variazione della riserva idrica, la percolazione profonda. In particolare la percolazione profonda (DP, deep percolation) è stato il parametro che ha consentito di calibrare e validare il modello poiché è stato confrontato a livello di trend e di valori con il deflusso di base del corso d’acqua del bacino, misurato settimanalmente alla chiusura del bacino mediante misure di portata per tutti gli anni in cui si è calcolato il bilancio (anni 2013, 2014, 2015 e 2016). Contemporaneamente sono state effettuate misure settimanali di livello piezometrico in quattro pozzi e l’andamento mediato dei quattro è stato altresì confrontato con la DP. Il territorio oggetto di indagine è stato il bacino del Fosso Santa Maria degli Angeli, piccolo bacino di circa 14 km2 posto a sud di Urbino, centro-Italia. I dati confermano la bontà del modello poiché i valori pluriennali di DP e deflusso differiscono appena del 10%; a scala temporale annuale c’è accordo tra i trends di DP, deflusso di base e falde acquifere, sia nelle fasi di salita che di discesa; in particolare il ritardo nella risalita del deflusso di base rispetto alla DP individua il tempo necessario all’acqua per effettuare il percorso ipogeo fino alla sezione di chiusura del bacino. Il modello ha poi consentito di ben caratterizzare le dinamiche idriche all’interno del suolo tramite il parametro della variazione della riserva idrica (∆R). Sono state inoltre effettuate misure di portata alla sezione di chiusura del bacino del fiume medio-alto Metauro, di cui il Santa Maria degli Angeli è sottobacino in sinistra idrografica, allo scopo di applicare il modello a un bacino di estensione maggiore. Ai fini del bilancio il lavoro ha anche previsto la realizzazione di carte di uso del suolo per gli anni di indagine, nonché due relative agli anni 1955 e 1997 al fine di studiare le variazioni di uso del suolo nel bacino. Il bilancio idrogeologico giornaliero su base fenologica è adatto per studi qualitativi e quantitativi delle risorse idriche a livello di bacino o di altra delimitazione territoriale e può essere ulteriormente migliorato attraverso una migliore definizione dei valori dei Kc e delle durate delle fasi fenologiche, l’utilizzo del double crop coefficient in luogo del single crop coefficient e una esatta attribuzione della tipologia di conduzione alle aree agricole (che è il dato che varia di anno in anno tra le superfici delle classi di uso del suolo).
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Dongwoo, Ko. "Mitigation Effects on Urban Flood by Installing an Underground Storage Box." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/202684.
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Winroth, Marcus. "On Gas Dynamics of Exhaust Valves." Licentiate thesis, KTH, Strömningsfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202719.
Повний текст джерелаАнотація:
With increasing effects of global warming, efforts are made to make transportation in general more fuel efficient. When it comes to internal combustion engines, the most common way to improve fuel efficiency is through ‘downsizing’. Downsizing means that a smaller engine (with lower losses and less weight) performs the task of a larger engine. This is accomplished by fitting the smaller engine with a turbocharger, to recover some of the energy in the hot exhaust gases. Such engine systems need careful optimization and when designing an engine system it is common to use simplified flow models of the complex geometries involved. The exhaust valves and ports are usually modelled as straight pipe flows with a corresponding discharge or loss coefficient, typically determined through steady-flow experiments with a fixed valve and at low pressure ratios across the valve. This means that the flow is assumed to be independent of pressure ratio and quasi-steady. In the present work these two assumptions have been experimentally tested by comparing measurements of discharge coefficient under steady and dynamic conditions. The steady flow experiments were performed in a flow bench, with a maximum mass flow of 0.5 kg/s at pressures up to 500 kPa. The dynamic measurements were performed on a pressurized, 2 litre, fixed volume cylinder with one or two moving valves. Since the volume of the cylinder is fixed, the experiments were only concerned with the blowdown phase, i.e. the initial part of the exhaustion process. Initially in the experiments the valve was closed and the cylinder was pressurized. Once the desired initial pressure (typically in the range 300-500 kPa) was reached, the valve was opened using an electromagnetic linear motor, with a lift profile corresponding to different equivalent engine speeds (in the range 800-1350 rpm). The results of this investigation show that neither the quasi-steady assumption nor the assumption of pressure-ratio independence holds. This means that if simulations of the exhaustion process is made, the discharge coefficient needs to be determined using dynamic experiments with realistic pressure ratios. Also a measure of the quasi-steadiness has been defined, relating the change in upstream conditions to the valve motion, i.e. the change in flow restriction, and this measure has been used to explain why the process cannot be regarded as quasi-steady.QC 20170306
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Mandal, Anirban. "Computational Modeling of Non-Newtonian Fluid Flow in Simplex Atomizer." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1202997834.
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Vaněk, Jakub. "Numerické modelování proudění v bezpečnostních objektech malých vodních nádrží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225377.
Повний текст джерелаАнотація:
The master´s thesis deals with the numerical modeling of flow in the emergency spillways of small dams. It is solved the flow rate capacity of a weir and of spillway called „duckbill-type“. Sharp crested weirs and long crested weirs are modeled using numerical simulations in ANSYS. Hydraulically complex spillway called „duckbill-type“ was modeled in the Flow-3D. The results of the discharge coefficients are compared with data in the hydraulic literature.
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Yildirim, Tugce. "Scrutinization Of Flow Characteristics Through Orifices." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612451/index.pdf.
Повний текст джерелаАнотація:
Orifices are essential devices for measurement and control of flow. It is important to define the flow field and understand the flow characteristics behind an orifice for the sake of reliability measures in many hydraulic engineering applications. Since analytical and experimental solutions are restricted, a numerical solution is obtained using volume of fluid (VOF) method with the CFD solver, FLUENT, for sharp crested orifices, orifice tubes and slots. The results are compared to the available data in the literaturealso a large spectrum of data collection has been achieved.
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Cihlář, Lukáš. "Plnicí systém vznětového motoru s proměnným průřezem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254359.
Повний текст джерелаАнотація:
The master´s thesis focuses on design of intake manifold with swirl flap for diesel engine. In addition to the design of sub-components of the intake manifold are also investigated the influence of new solutions on engine parameters. The influence of the new solution is compared to the original version and a reference model simulating intake manifold used by competitors. After simulation of thermodynamics and fluid flow are evaluated each variants.
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Makhlouf, Samir. "Contribution à l'étude de l'impact de la cavitation sur les processus physiques de l'atomisation primaire des jets d'injecteurs essence." Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0005/document.
Повний текст джерелаАнотація:
Afin de se rapprocher des conditions du mélange homogène du moteur essence, plusieurs fluides sont injectés dans l'atmosphère à une pression amont et une température variées. Cinq prototypes d'injecteurs réels trois-trous de Continental ont été utilisés. En augmentant la pression d'injection, l'écoulement passe par quatre régimes où le niveau de développement de cavitation varie. Le coefficient de décharge Cd dépend essentiellement du nombre de cavitation. Au point critique de cavitation, deux corrélations ont été obtenues reliant respectivement Cd et le nombre de cavitation critique au nombre de Reynolds correspondant. Le jet en champ proche est gouverné par trois nombres sans dimensions : celui de Weber, de Reynolds et de cavitation. L'effet de chacun d'eux sur l'angle du jet à la sortie a été obtenu. La comparaison des résultats entre deux injecteurs a montré que le rapport entre la longueur et le diamètre de l'orifice est d'une influence d'ordre 1 sur l'angle du jetIn order to get closer to the homogeneous mixture conditions of a gasoline engine, different fluids are injected into the atmosphere at varying upstream pressure and temperature. Five three-hole real injector prototypes from Continental were used. When injection pressure is increased, the internal flow goes through four regimes where the cavitation development level varies from one to another. The discharge coefficient Cd was found mainly dependent on the cavitation number. At the cavitation critical point, two correlations between Cd and the critical cavitation number on one side respectively, and the correspondent Reynolds number on the other side were found. The near field jet is ruled by three dimensionless numbers : Weber, Reynolds and cavitation. The effect of each one of them on the jet angle at the orifice outlet was obtained. By comparing the results of two injectors, it was found that the length over diameter ratio has a first order influence on the jet angle
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Major, Jakub. "Zatopení nízkých pravoúhlých přelivů se širokou korunou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227543.
Повний текст джерелаАнотація:
This diploma thesis deals with submergence of low rectangular sharp-edged broad-crested weirs. From measurement of water levels in front of and behind of weir at different discharges and different weir heights, were determined values of submergence coefficient depending on relative height of submergence. From these values were determined the equation of submergence coefficient. Measured values were compared which results measurements, which are given in professional literature.
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Jobánek, Stanislav. "Zhodnocení kapacity nízkých přelivů při převádění extrémních průtoků." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226875.
Повний текст джерелаАнотація:
The thesis deals with values of overfall discharge coefficients for commonly used types of low weirs. Comparison of their values with values based on established procedures. Determination of low weir capacity at free and submerged overfall.
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Alsaiari, Abdulmohsen Omar. "Augmentation of Jet Impingement Heat Transfer on a Grooved Surface Under Wet and Dry Conditions." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/98502.
Повний текст джерелаАнотація:
Array jet impingement cooling experiments were performed on flat and grooved surfaces with the surface at a constant temperature. For the flat surface, power and temperature measurements were performed to obtain convection coefficients under a wide range of operating conditions such as jet speed, orifice to surface stand-of distance, and open area percentage. Cooling performance (CP) was calculated as the ratio between heat transfer and fan power. An empirical model was developed to predict jet impingement heat transfer taking into account the entrainment effects. Experimental results showed that jet impingement can provide high transfer rates with lower rates of cooling cost in comparison to contemporary conventional techniques in the industry. CP values over 279 were measured which are significantly higher than the standard values of 70 to 95 in current technology. The model enhanced prediction accuracy by taking into account the entrainment effects; an effect that is rarely considered in the literature. Experiments on the grooved surfaces were performed at dry and wet surface conditions. Under dry conditions, results showed 10%~55% improvement in heat transfer when compared to the flat surface. Improvement percentage tends to be higher at wider gaps between the array of orifices and the grooved surface. An improvement of 30%~40% was observed when increasing Re either by increasing orifice diameter or jet speed. Similar improvement was observed at higher flow open area percentages. No significant improvement in heat transfer resulted from decreasing the size of the grooves from 3.56mm to 2.54mm. Similarly, no noticeable change in heat transfer resulted from changing the relative position of the jets striking the surface at the top of the grooves to the bottom of the grooves. Deeper grooves with twice the depth gave statistically similar average heat transfer coefficients as shallower grooves. Under wet conditions, a hybrid cooling technique approach was proposed by using air jets impinging on a grooved surface with the grooves containing water. The approached is proposed and evaluated experimentally for its feasibility as an alternative for cooling towers of thermoelectric power plants. Convection heat and mass transfer coefficients were measured experimentally using the heat mass transfer analogy. Results showed that hybrid jet impingement provided high magnitudes of heat flux at low jet speeds and flow rates. High coefficients of performance CP > 3000, and heat fluxes > 8,000W/m2 were observed. Hybrid jet impingement showed 500% improvement as compared to jet impingement on a dry flat surface. CP values of hybrid jet impingement is 600% to 1,500% more as compared to performance of air-cooled condensers and wet cooling towers. Water use for hybrid jet impingement cooling is efficient since evaporation energy is absorbed from the surface directly instead of cooling air to near wet-bulb temperature.PHD
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Šelepa, Milan. "Středně dobá předpověď průtoků vody měrným profilem toku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227194.
Повний текст джерелаАнотація:
The diploma thesis is focused on the long term prediction of mean monthly flows in hydrometric profile for purposes of reservoir control optimization and optimization of reservoir systems. Discharges were predicted using by artificial neural network method. Predicted flows were statistically evaluated by relevant coefficients and then compared with the measured flows for given river hydrometric profiles.
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Isaksson, Frida. "Pressure loss characterization for cooling and secondary air system components in gas turbines." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-64528.
Повний текст джерелаАнотація:
There is a constant struggle to increase the efficiency in gas turbines, where one method is to have a higher inlet temperature to the turbine. Often, this results in temperatures higher than the critical temperature of the materials, which makes cooling of the components an important part of the turbine. The cooling air is tapped from the compressor, and has hence required work while being compressed, but since it is removed from the thermodynamic cycle it will not provide any work in the turbine stages. Therefore, it is important to understand the losses in the cooling system to be able to use the smallest amount of cooling air possible, while still cool sufficiently to not decrease the turbine’s lifetime. The pressure losses in the cooling and secondary air systems are due to either friction or minor losses; contractions, expansions and bends. The losses can be described by a discharge coefficient, ; a rate of how close the actual mass flow is to the ideal mass flow, or a pressure loss coefficient, ; a rate of the pressure drop. In the cooling and secondary air systems there are orifices and cooling geometries. These can have different geometrical properties depending on application, and thereby have different heat transfer performances and causing a higher or lower pressure drop. At Siemens Industrial Turbomachinery AB, SIT AB, a one-dimensional in-house program named C3D is used for thermal calculations and calculations of flow properties of internal cooling flow networks. The program uses hydraulic networks consisting of nodes and branches to simulate the flow inside the components. Correlations used for describing pressure losses have been collected and divided depending on their valid ranges, with the aim to make pressure loss calculations easier. A MATLAB code have been developed, which, depending on input parameters, separates the correlations and returns a plot with the correlations that can be used. In order to make the code as useful as possible, a few assumptions were made; curve fitting of correlations which were only available as plots and interpolation to get larger valid ranges for some cases. These assumptions will influence the results, but the code will still be able to give an indication of which correlation to use, and hence, the objective is fulfilled. Simulations in one dimension are commonly used, since it is less time consuming than three-dimensional modelling. Therefore, with focus on the pressure losses, a one-dimensional model of a blade in the in-house program C3D has been evaluated using a three-dimensional model in the CFD program Ansys CFX. Also, two new models were created in C3D; both with geometrical properties and pressure loss coefficients adjusted to the CFX model, but the first model is using the same hydraulic network as in the evaluated, reference, model while the second is using a new network, built according to the streamlines in CFX. The resulting mass flows in the C3D models were compared to the mass flows in the CFX model, which ended in the conclusion that it is hard for the one-dimensional models to understand the complex, three-dimensional flow situations, even when adjusting them to the CFX model. Anyhow, the adjustments made the model somewhat closer to the three-dimensional case, and hence CFX should be used in an earlier stage when developing C3D models.
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Sahiner, Halit. "Hydraulic Characteristics Of Tyrolean Weirs Having Steel Racks And Circular-perforated Entry." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614247/index.pdf.
Повний текст джерелаАнотація:
Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.
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Soriano, Bruno Souza. "Análise numérica transiente com validação experimental do escoamento em motores de combustão interna considerando diferentes aberturas de válvula." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2015. http://hdl.handle.net/10183/118887.
Повний текст джерелаАнотація:
Com o crescente aumento dos problemas ambientais relacionados à emissão de poluentes, normas cada vez mais rigorosas estão sendo implementadas para diminuir a emissão de gases nocivos provenientes da queima de hidrocarbonetos em motores de combustão interna. Um importante fator que influencia na geração de gases poluentes em motores é o comportamento do escoamento no cilindro, desde o início da admissão até a fase de combustão. O presente trabalho realiza um estudo numérico com validação experimental do escoamento no motor Honda GX35, considerando diversas aberturas de válvula fixas e diferenças de pressão para gerar o escoamento. A validação da metodologia numérica é realizada através da comparação dos resultados do coeficiente de descarga para todas as aberturas de válvula utilizadas. A medição da vazão de ar na metodologia experimental é realizada com um anemômetro de filme quente de aplicação automotiva, calibrado para as condições do teste. Já a metodologia numérica utiliza dois modelos de turbulência, k-ω SST e k-ε standard. Os resultados numéricos apresentaram boa concordância com os experimentais para ambos os modelos adotados, quanto ao coeficiente de descarga. Entretanto, a diferença de comportamento do escoamento no interior do cilindro é elevada, pois o modelo k-ω SST é capaz de captar a oscilação transiente do jato que se forma na saída da válvula, inexistente no k-ε standard. O comportamento transiente causa uma significativa variação da vorticidade média em um plano perpendicular ao cilindro, com o escoamento trocando de direção principal de rotação em alguns instantes. Dados numéricos médios e de variação ao longo do tempo para swirl e tumble também são apresentados e discutidos. Ao analisar a oscilação da vazão mássica na fronteira de saída do domínio, frequências de aproximadamente 1300 Hz são captadas. Tais frequências são confrontadas com resultados experimentais obtidos pelo presente grupo de pesquisa para medições de oscilação de pressão no coletor de admissão do mesmo motor. O desvio percentual relativo para a frequência de oscilação é de 0,3%, o que demonstra a correta predição, tanto do fenômeno de desprendimento de vórtice quanto do coeficiente de descarga obtido através do modelo de turbulência k-ω SST.With the increasing environmental problems concerning pollutant emissions, stringent standards have been applied in order to decrease harmful gases produced by the hydrocarbons combustion in internal combustion engines. The flow behaviour within the cylinder is an important factor that affects the emission’s formation in engines, since the intake stroke until the combustion. This work performs a numerical study with experimental validation of fluid flow at Honda GX35 engine, considering different fixed valve lifts and suction pressures to generate the flow. The validation of the numerical methodology is made through the discharge coefficient and flow pattern comparisons for all valve lifts utilized. The mass flow rate in the intake system is measured with an automotive hot film anemometer, calibrated for the test’s conditions. Regarding the computational solution for the turbulent air flow, two turbulence models were utilized: SST k-ω and k-ε standard. Although the numerical results presented a good agreement with the experimental data concerning the discharge coeficient, the flow pattern comparisons presented a high discrepancy among the models utilized. The SST k-ω model is capable to capture the transient behaviour of the jet formed in the valve exit, constituting the main difference between them. The transient oscillation causes a significant difference of mean vorticity in a cylinder section plane, with the bulk flow changing its main rotation along the time. The averaged and transient numerical data of swirl and tumble are presented and discussed. In the frequency analysis of the numerical mass flow rate oscillations, obtained at the outlet boundary, presented an average value about 1300 Hz. Such frequencies, when compared with experimental results obtained by the present research group for the pulsating pressure waves into the intake duct of the same engine, had a relative percentage deviation of 0.3%. The agreement between the results using the SST k-ω model reveals the correct prediction of vortex shedding frequency and discharge coefficient.
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Sasson, Jonathan. "Small Scale Mass Flow Plug Calibration." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1417540797.
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Holt, Gavin J. "Experimental Characterization of Baffle Plate Influence on Turbulent and Cavitation Induced Vibrations in Pipe Flow." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2765.
Повний текст джерелаАнотація:
Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a range of different baffle plate geometries. The baffle plates explored contained varying hole sizes that ranged from 0.159 cm to 2.54 cm, with the total through area, or openness, of each baffle plate ranging between 11% and 60%. Plate thickness varied from 0.32–0.635 cm. Reynolds numbers ranged from 5 x 10^4 -85 x 104. The results show that the cavitation design limits are function of size scale effects and the loss coefficient only. The results also show that the loss coefficient for a baffle plate varies not only with total through area ratio, but also due with the plate thickness to baffle hole diameter ratio. Pipe wall vibrations were shown to decrease with increased through area ratio and increased thickness to diameter ratios. An investigation was also performed to characterize the attenuation of vibration in the streamwise direction of a baffle plate. It was show that the attenuation was largely effected by the presence of cavitation. Attenuation was shown to be a function of the geometry of the baffle plate. This work resulted in empirical models that can be used for predicting pipe vibration levels, the point of cavitation inception, and the streamwise distance where the attenuation of vibration levels caused by a baffle plate occurs.
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Jinek, Josef. "Vliv drsnosti povrchu stěny na součinitel výtoku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227834.
Повний текст джерелаАнотація:
This thesis deals with the influence of the wall roughness on discharge coefficient of sharp-edged circular bottom orifice. It supposed to verify, summarize and extend knowledge of orifice discharge. Author of this thesis determine a discharge coefficient by measurement. Values of discharge coefficient were measured for roughness of the wall represented by different diameters of grains and these values were compared with available values published in specialized bibliography by different scientists. At the thesis end was made a summary evaluation.
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Duda, Petr. "Optimalizace polohy propelerové turbíny v kašně." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231499.
Повний текст джерелаАнотація:
The thesis contains basic information about propeler turbines. It deals with the correct location in the fountain so as to ensure the highest possible performance. Part of the work is devoted to the all-weather resulting blade to blade channels and their impact on the room is filled with diffuser.
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Šváb, Jiří. "Tenkostěnný pravoúhlý přeliv s přítokovou šachtou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392000.
Повний текст джерелаАнотація:
The thesis is divided into literary research and practical part (own measurement). The content of the literary research is a description of the flow over thin-plate rectangular weir. The practical part is focused on a description of the model, measuring equipment and measurement. The results are evaluation of lower and upper surface of nappe, determination of discharge coefficient, coefficient of relative length of shaft, limit value of relative length of shaft for uninfluenced shape of nappe.
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Zmítko, Jakub. "Tenkostěnný pravoúhlý přeliv bez bočního zúžení ovlivněný šířkou koryta." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409724.
Повний текст джерелаАнотація:
The diploma thesis deals with the propagation of a weir (channel) width on the weir capacity. The influence rate is analyzed by laboratory measurements on models with a weir (channel) width of 0,02 m to a width of 0,50 m. Different heads are analyzed and different discharges that calculate the discharge coefficient. The results are compared with previous works, especially with the work of Kindsvater and Carter (1957) and of Schoder and Turner (1929), where the same procedures are used to calculate discharge coefficients. The thesis contains a theoretical introduction to the problem of thin-plate weirs and the problem of the formation of the boundary layer in the flow of liquid, following with the analytical part. In the analytical part, the results of measurements, their comparison, and evaluation are published. The work is completed with evaluation and recommendations.
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MOUSAVI, NADOSHANI SEYED SAEID. "Composition des lois élémentaires en hydrologie régionale : application à l'étude des régimes de crue." Grenoble 1, 1997. http://www.theses.fr/1997GRE10165.
Повний текст джерелаАнотація:
Un evenement hydrologique est souvent defini d'apres plusieurs variables aleatoires presentant un certain degre de liaison. L'etude probabiliste de cet evenement necessite alors la composition de lois de probabilite. Nous avons considere deux cas d'applications : 1) l'extrapolation de la distribution du debit de pointe et du debit seuil ; 2) l'estimation du quantile du debit de crue a l'aval d'une confluence. Nous avons teste plusieurs fonctions de deux variables : les modeles de farlie-gumbel-morgenstern, de farlie et hashino, en utilisant des echantillons sup-seuil. Pour ce dernier modele, nous utilisons le coefficient de correlation obtenu avec la totalite de l'information (evenements concomitants et non concomitants). Les performances des modeles de composition ont ete testees sur des donnees reelles, puis sur des donnees simulees a l'aide du modele de generation de pluies journalieres shypre, du modele pluie-debit gr4j et d'un modele de liaison spatiale des pluies. Nous avons enfin etudie les hydrogrammes d'apport a injecter dans un modele hydraulique, de facon a rester homogene en frequence sur tout le lineaire de la riviere.
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Ballu, Aurélien. "Étude numérique et expérimentale de l'écoulement turbulent au sein des passes à poissons à fentes verticales. Analyse de l'écoulement tridimensionnel et instationnaire." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2256/document.
Повний текст джерелаАнотація:
L'objectif de cette thèse est de caractériser l'influence de la présence d'obstacles dans les passes à poissons à fentes verticales. Deux types d'éléments sont couramment insérés, à l'heure actuelle, dans les passes : les seuils et les macro-rugosités. Dans un premier temps, l'effet de ces deux dispositifs à la fois sur l'écoulement et sur le comportement des poissons est étudié. Dans le but de favoriser le passage des petites espèces à travers le dispositif de franchissement, une solution technique est ensuite proposée, sous la forme de plusieurs rangées de cylindres flexibles placées en sortie de fente. La caractérisation du comportement hydraulique d'une passe à poissons équipée de ces obstacles est effectuée par des mesures expérimentales de niveau d'eau à l'aide de sondes acoustiques et des mesures de vitesses tridimensionnelles avec un vélocimètre acoustique à effet Doppler (ADV). La base de données générée par ces mesures est ensuite utilisée pour définir une loi de dimensionnement, qui prend en compte les paramètres influençant le fonctionnement hydraulique de l'ouvrage en vue d'améliorer sa conception. Les simulations numériques 3D instationnaires URANS et LES de l'écoulement permettent une analyse volumique fine des grandeurs caractéristiques de la turbulence qui règne dans les bassins en fonction du type d'obstacle inséré. En obstruant une partie de la fente, la présence d'un seuil accentue la tridimensionnalité de l'écoulement tandis que les macro-rugosités créent une zone de plus faible vitesses et des abris utilisables par les espèces de fonds. L'insertion des structures souples permet une meilleure dissipation de l'énergie du jet et réduit l'énergie cinétique turbulente dans une partie du volume des bassins. Les manipulations réalisées avec différentes espèces de poissons, permettent de mieux comprendre l'effet de la modification des grandeurs cinématiques de l'écoulement, par l'insertion d'obstacles, sur le comportement des poissons pour pouvoir adapter les passes à poissons existantes aux espèces dotées de faibles capacités de nageThe aim of this work is to characterize the influence of two kinds of obstacles, sills and macro-roughnesses, on the flow inside a vertical slot fishway (VSF) and the behavior of several species of fish. Another objective is to study a technical solution to allow the passage of small fish species, which take the form of flexible cylinders placed in the jet at the entrance of each pool of the VSF. A hydraulic characterization is made by experimental measurements of the water level in each pool with acoustic sensors and by measurements of three-dimensional velocity components with an acoustic Doppler velocimeter (ADV). The data acquired by these measurements are then used to define a predictive law that takes into account the presence of sills or macro-roughnesses, to help the design of devices that are as efficient as possible. Unsteady RANS and LES three-dimensional numerical simulations of the flow allow performing a careful volume analysis of the turbulence characteristics inside the pools when obstacles are presents in the flow. By obstructing a part of the slot, sills enhance the three-dimensionality of the flow while macro-roughnesses generate a low velocity layer and shelters for benthic species. Flexible elements produce a better dissipation of the energy of the jet and reduce the turbulent kinetic energy in a part of the volume of the pools. The effect of the modification of the flow kinematic properties, by the presence of obstacles, on the behavior of various fish species is evaluated. It provides important insights on how to adapt the flow in existing fishways to fish species with low swimming capacity
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OUAJJI, HASSAN. "Etude de proprietes de transport d'un plasma de melange air-cuivre : modelisation de la colonne d'arc." Clermont-Ferrand 2, 1986. http://www.theses.fr/1986CLF21034.
Повний текст джерелаАнотація:
Calcul des coefficients de conductivite thermique, de conductivite electrique et de viscosite du melange air-cuivre a la pression atmospherique pour des temperatures comprises entre 5000 k et 14000 k et differentes valeurs de la teneur en cuivre. Dans les memes conditions de temperature et de pression, la determination de la composition d'equilibre du melange met en evidence l'evolution de la population des differentes especes chimiques en presence en fonction de la teneur en cuivre. Les caracteristiques macroscopiques de la colonne (champ electrique, profil de temperature) sont obtenues a partir du modele energetique de elenbaas-heller
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Borunský, Tomáš. "Optimalizace procesu tlakového lití VN přístrojových transformátorů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228552.
Повний текст джерелаАнотація:
This thesis deals with choises of using mathematical statistics when optimising the compression casting process of high-voltage device transformer. There is a theoretical consideration to be found in the introduction which concerns the compression casting itself and all necessary information connected with it. Then there is a key numerical analysis part following. In the first instance there are variability problems of individual casting device discussed and then a regression analysis made to demonstrate and prove a link between the partial discharge and the key parameters of casting process. Finally an “optimal” casting sequence is suggested and alternative attitude problems with the assistance of Design of Experiments (DOE) are discussed.
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Wang, Yue. "Numerical Studies of Flow and AssociatedLosses in the Exhaust Port of a Diesel Engine." Doctoral thesis, KTH, Mekanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134844.
Повний текст джерелаАнотація:
In the last decades, the focus of internal combustion engine development has moved towards more efficient and less pollutant engines. In a Diesel engine, approximately 30-40% of the energy provided by combustion is lost through the exhaust gases. The exhaust gases are hot and therefore rich of energy. Some of this energy can be recovered by recycling the exhaust gases into turbocharger. However, the energy losses in the exhaust port are highly undesired and the mechanisms driving the total pressure losses in the exhaust manifold not fully understood. Moreover, the efficiency of the turbine is highly dependent on the upstream flow conditions. Thus, a numerical study of the flow in the exhaust port geometry of a Scania heavy-duty Diesel engine is carried out mainly by using the Large Eddy Simulation (LES) approach. The purpose is to characterize the flow in the exhaust port, analyze and identify the sources of the total pressure losses. Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation results are included for comparison purposes. The calculations are performed with fixed valve and stationary boundary conditions for which experimental data are available. The simulations include a verification study of the solver using different grid resolutions and different valve lift states. The calculated numerical data are compared to existent measured pressure loss data. The results show that even global parameters like total pressure losses are predicted better by LES than by URANS. The complex three-dimensional flow structures generated in the flow field are qualitatively assessed through visualization and analyzed by statistical means. The near valve region is a major source of losses. Due to the presence of the valve, an annular, jet-like flow structure is formed where the high-velocity flow follows the valve stem into the port. Flow separation occurs immediately downstream of the valve seat on the walls of the port and also on the surface of the valve body. Strong longitudinal, non-stationary secondary flow structures (i.e. in the plane normal to the main flow direction) are observed in the exhaust manifold. Such structures can degrade the efficiency of a possible turbine of a turbocharger located downstream on the exhaust manifold. The effect of the valve and piston motion has also been studied by the Large Eddy Simulation (LES) approach. Within the exhaust process, the valves open while the piston continues moving in the combustion chamber. This process is often analyzed modeling the piston and valves at fixed locations, but conserving the total mass flow. Using advanced methods, this process can be simulated numerically in a more accurate manner. Based on LES data, the discharge coefficients are calculated following the strict definition. The results show that the discharge coefficient can be overestimated (about 20 %) when using simplified experiments, e. g. flow bench. Simple cases using fixed positions for valve and piston are contrasted with cases which consider the motion of piston and/or valves. The overall flow characteristics are compared within the cases. The comparison shows it is impossible to rebuild the dynamic flow field with the simplification with fixed valves. It is better to employ LES to simulate the dynamic flow and associated losses with valve and piston motion.QC 20131204