|
|
Losses in a pipe line because of the flow of mixed substratums
Vlasák, Bohdan ; Beňo, Zdeněk (referee) ; Pěček, Jan (advisor)
Introductory part of this thesis is aimed on theoretical description, principle and building of biogas stations, which require solution of many different problems. A specific group of the problems concern transport of mixed substrates of different concentrations both in and outside the area of biogas station. A major part of the substrate transport is done by pumping it in pressure pipeline. Experimental work consists of design and description of a measuring circuit. Graphic characteristics for water and gas loss levels are drawn from the measured readings. Multiples of pressure losses by flowage of substrates with different levels of dry basis are graphically expressed with a help of correction coefficients.
|
|
|
Advanced Solution to Piston Assembly Dynamics
Dlugoš, Jozef ; Furch,, Jan (referee) ; Kučera, Pavel (referee) ; Novotný, Pavel (advisor)
Hlavní cíl této práce je vyvinout pokročilý výpočtový model dynamiky pístové skupiny. Kontakt mezi pístem a válcem je zprostředkován skrz vrstvu maziva nebo pomocí kontaktu nerovností. To vede k různým režimům mazání, tudíž k různým silovým interakcím působících na plochy kontaktní dvojice. Během řešení hydrodynamiky a kontaktu nerovností, je nutné zahrnout deformaci pístu a válce do výpočtu—přirozeně iterační proces. Jelikož požadavky na výpočtovou síť kontaktních sil a deformaci těles se liší, byl navržen robustní mapovací algoritmus. Výsledky vyvinutého výpočtového nástroje jsou experimentálně verifikovány. Pro tento účel je uskutečněno měření sekundárního pohybu pístu pomocí laserových snímačů vzdálenosti. Měření je vykonáno na experimentálním motoru s bočním vedením ventilů a průhlednou hlavou válce, aby byl přítomen kompresní tlak ve spalovací komoře. Naměřený boční pohyb pístů je znehodnocen. Proto je další analýze potrobeno pouze úhlové natočení pístů. Shoda mezi naměřenými a vypočítanými výsledky variuje pro různé části pracovního cyklu. Dobrá shoda je dosažena během komprese a expanze. Naopak výrazné rozdíly nastávají, když boční síla dosahuje nízkých hodnot: sání a výfuk. Hlavní přínos této práce je vytvoření výpočtového nástroje, který je schopný zahrnout výše popisované jevy, které mají podstatný vliv na dynamiku pístové skupiny. Bohužel to vede k dlouhým výpočtovým časům, zvláště když je zahrnuta deformace. Tento problém řeší navržený paralelní výpočet. To je založeno na paralelizaci podprogramu během vyčíslování citlivostní analýzy. Tímto způsobem je řádově redukován výpočtový čas.
|
|
|
Crank mechanism with a high mechanical efficiency
Drápal, Lubomír ; Tůma, Jiří (referee) ; Páv,, Karel (referee) ; Píštěk, Václav (advisor)
This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.
|
|
|
Three-cylinder inline diesel engine with an eccentric crank for commercial vehicles
Domský, Viktor ; Kaplan, Zdeněk (referee) ; Píštěk, Václav (advisor)
The goal is to investigate the influence of eccentricity on the force between the piston and the cylinder liner and the influence on balancing of the crank mechanism. For a selected eccentricity suggest a balancing method and perform stress analysis of crankshaft considering torsional vibration. Eccentricity is chosen by the ratio of centric and eccentric mechanism of friction work. The paper shows the effect of eccentricity on the selected kinematics values. Stress analysis is done in the software ANSYS. Using selected eccentricity the friction work was reduced by 10 %.
|
|
|
General Solution of Cranktrain Mechanical Losses
Honc, Robert ; Píštěk, Václav (referee) ; Novotný, Pavel (advisor)
Master’s thesis deals with the description of cranktrain friction and presents and describes experimental cranktrain friction loss evaluations and computational cranktrain friction loss evaluations. The main problem is the creating software solution of selected computational friction loss evaluations that leads to calculation of cranktrain friction losses. Master’s thesis describes chosen computational friction loss methods and the subsequent creation of the software solution. After application on chosen internal combustion engine, it evaluates the results and draws conclusions about functionality of the software solution.
|
|
|
General Solution of Valvetrain Mechanical Losses
Mynařík, Aleš ; Maršálek, Ondřej (referee) ; Novotný, Pavel (advisor)
This master's thesis deals with the determination of mechanical losses in the valvetrain of the combustion engine. It describes the computational and experimental methods of determining the mechanical losses of valve mechanism. The practical part of the thesis focuses on the programing of structures in Matlab. This application calculates the values of mechanical losses of valvetrain and displays their graphical representation. This program is used for computing the mechanical losses of the selected real engine.
|
|
|
Four-cylinder petrol engine with eccentric crank mechanism for passenger vehicles
Mlčoch, Pavel ; Kaplan, Zdeněk (referee) ; Píštěk, Václav (advisor)
This Diploma Thesis is aimed at exploring the potential of offset crankshaft mechanism for four cylinder inline petrol engine in terms of reducing the frictional losses of the piston group. Thesis deals with the influence of eccentricity on kinematics, dynamics and balance of the crank train. Furthermore, specific crankshaft balancing is elaborated and applied on 3D CAD model of the crankshaft. Calculation of fatigue safety factor using the advanced LSA method that takes into consideration the effect of forced torsional vibration and utilizes outputs from the FEA software (ANSYS APDL) is performed as well. Thesis also includes design of two options of rubber torsion damper mounted on the engine belt pulley and the follow-up choosing of the more advisable one.
|
|
|
Modelling in Engineering
Holec, Tomáš ; Rozehnalová, Petra (referee) ; Popela, Pavel (advisor)
The aim of this bachelor thesis is to determine the optimal parameters of pump impeller in order to minimize friction loss and disc loss. The proposal has been implemented by a mathematical model in Matlab. The thesis consists of theoretical and practical part. The first four chapters summarize the theroretical background that is necessary for creating the mathematical model for the losses of an impeller. In the fifth chapter the implementation of the mathematical model in Matlab is presented and results for particular types of pumps are discussed.
|
|
|
Comparing grades axial steam turbines for various media
Staněk, Štěpán ; Fiedler, Jan (referee) ; Kracík, Petr (advisor)
Aim of the thesis is to design a single-stage axial steam turbine with impulse blading type for two different media with identical input parameters at input of stator and pressure behind the impeller. Calculation is made for water steam and organic fluid R134a. Main part of this thesis is termodynamic calculation and its optimalization in order to achieve maximum output and efficiency of the stage for both working fluids. At the end of the thesis an alternative calculation of impeller friction losses is presented.
|
|
|
Crank mechanism with a high mechanical efficiency
Drápal, Lubomír ; Tůma, Jiří (referee) ; Páv,, Karel (referee) ; Píštěk, Václav (advisor)
This document describes the possibilities of increasing the mechanical efficiency of the crank train of an internal-combustion engine. For this purpose, a concept with a reduced number of main bearings is chosen and its contribution is verified experimentally. The proposed solution consists of an innovative crankshaft design of a four-cylinder spark-ignition engine with only three main journal bearings and laser-welded sheet metal crank webs. The new design is compared to the mass-produced one in terms of friction losses, vibrations and loading of engine parts by means of simulations of crank train dynamics using the Multi-Body System. The increase in vibration, accompanied by a reduction in friction losses, is compensated by a torsional vibration damper and its effect is experimentally verified. Experimental research of laser welds on the crankshaft in terms of fatigue life is also described. The overall potential is also summarised and further possible development of this innovative and patented design is outlined.
|
guest ::
