National Repository of Grey Literature 45 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Condition Simulation in Vehicle Aerodynamics Computation
Čavoj, Ondřej ; Sloupenský, Zdeněk (referee) ; Popela, Robert (referee) ; Píštěk, Václav (advisor)
Several types of discrepancies have been examined between CFD simulations, wind tunnel measurements and real world conditions. The results of different wheel rotation methods show that while stationary approaches can often substitute real unsteady wheel rotation, they can also be very sensitive to the exact angular positioning of wheel rims. Using both measured and computed flow fields, the lower part of wheel wake was identified as a key area, showing differences between rotation methods and sources of simulation errors in general. It was also shown that the level of detail in tyre geometry and its deformation near contact patch do not have a large impact on accuracy. Due to the absence of tyre rotation, the tyre sidewall was identified as an important place of flow separation with large effect on flow field and forces. Angle of attack study confirmed that assessing purely straight-line drag causes its under prediction compared to real-world values. This judgement would however benefit from obtaining data in more adverse conditions compared to those currently available. Finally, tyre radial expansion was investigated, causing a drop in drag with increasing vehicle velocity and altering the flow around the rear bodywork. Ignoring this effect can therefore negatively influence the aerodynamic development of a vehicle.
Numerical Study Of Pulsating Jet At Moderately Small Reynolds Numbers
Dolinský, Jiří ; Doupník, Petr (referee) ; Popela, Robert (advisor)
This numerical study is focused on axisymmetric pulsatile jets of moderately small Reynolds numbers and their physics which has not been fully understood so far. The main goal of the thesis is to investigate and assess the effect of introducing time-harmonic velocity component onto the steady velocity component. At first, the steady case was resolved and verified, afterwards the pulsation was introduced and the unsteady solution was carried out. The numerical solution for steady axisymmetric jet has been verified based on asymptotic solution obtained by Hermann Schlichting [44]. Moreover, an original Schlichting's solution was corrected according to an experimental observation obtained by Andrade and Tsien [1], which reduces solution singularity in the near-nozzle area. This correction was proven to be a first-order correction of the original asymptotic solution from a mathematical standpoint by Revuelta et al [36]. The analytical solution was developed in MATLAB while for the numerical simulation, the Ansys Fluent was used and the time-accurate integration of the Navier-Stokes equations based on pressure-correction approach was employed in order to solve the problem. The pulsatile jet was calculated for a set of different parameters in order to assess their impact on the jet evolution. Finally, the possible application in the industry with regards to elimination of pollutants emerging during the combustion process was discussed.
Design of folding propeller for UAVs
Dítě, Radovan ; Dvořák, Petr (referee) ; Popela, Robert (advisor)
This master's thesis deals with the design of foldable propeller for UAVs. The design of the foldalble propeller is created based on theory of propellers and also on tha detail ana-lyzis of existing foldalble propellers with similar dimensions. The propeller is then manufac-tured and tested. One of the part of this thesis also describes design of central hub. At the end the methodical procedure of creating foldable propellers is suggested.
CFD analysis of icing effects on commuter aircraft configuration
Zima, Martin ; Navrátil, Jan (referee) ; Popela, Robert (advisor)
The Diploma Thesis concerns investigation of icing effects at L 410 NG aircraft. The aircraft is certified under FAR/CS/AP-23 Commuter category. An analysis was performed for existing Pneumatic De-icing Boots System at the wing area according to three flight configurations and icing conditions referring to document Part 25 Appendix C and O. The analysis was done by CFD solver FENSAP-ICE for various runs with respect to the icing envelope. Cases were assigned as two 2D cross-sections situated at the aircraft’s wing aileron part. Cross-sectional Reynold’s number oscillate between 4.5–8.5×106. Automatic operation of Pneumatic De-icing Boots System was proposed. Attention was paid to the ice accretion aft to the Pneumatic De-icing Boots System. The Appendix (Příloha) P6 contains an English written Article concerning main Diploma Thesis sections.
Study of Inertial Particle Separator in a typical turboprop engine
Skála, Adam ; Doupník, Petr (referee) ; Popela, Robert (advisor)
This thesis focuses on ingestion of foreign objects into standard turboprop engine GE H80 situated in aircraft Let L-410 Turbolet. Aim of this study is to create methodology of numerical simulation of particle movement inside the engine, which could be used during design process of Inertial Particle Separator device. Thesis consists of backward-facing step benchmark study which validates used methodology. Second part describes flow field calculation and numerical setup. The last part is dedicated to particle tracking analysis. Simulated trajectories are visually investigated, and coordinates of particle impacts at 1st rotor of a compressor are correlated to position of real observed damage.
Aerodynamic analysis of the Aircar 5.0 flying car prototype
Jánošík, Tomáš ; Jebáček, Ivo (referee) ; Popela, Robert (advisor)
This thesis focuses on CFD analysis of the Aircar 5.0 flying car prototype. The theoretical part covers basic information about the connection between the aerodynamics of airplanes and cars as well as cars themselves. The computational part begins with the calibration of the mathematical model, continues with the CFD simulations, which have the role to determine basic aerodynamic characteristics of the Aircar in vehicle mode. There are several configurations tested to find out their influence on aerodynamic stability and their advantages and disadvantages are summed up in the conclusion chapter.
Preliminary aerodynamic analysis of remotely controlled model with jet propulsion
Novák, Ondřej ; Zikmund, Pavel (referee) ; Popela, Robert (advisor)
This bachelor´s thesis deals with aerodynamic analysis of unmanned aircraft and subsequent changes to design of wing, its position and wing-fuselage junction. In this work emphasis is laid on flow separation, its interaction with other flow structures and its influence on aerodynamic properties. The goal of these changes to the aircraft is ensuring sufficient stability and controllability in low as well as high angle of attack flight. AVL, XFLR5 and CFD methods were used in the thesis. In case of inaccuracy of CFD calculation, two backup wing related modifications were prepared.
Creation of educational experiment for Aerodynamics I course
Fenech, Daniel ; Navrátil, Jan (referee) ; Popela, Robert (advisor)
Cílem bakalářské práce je vytvořit semestrální projekt pro studenty kurzu Aerodynamika I, který dále využijí pro lepší porozumění a získání zkušeností, jak lze určit aerodynamické charakteristiky pomocí výpočtů a pomocí aerodynamického tunelu. Nejdůležitějšími kroky je získání geometrie modelu pomocí 3-D skenování a manipulace se skenovanou položkou tak, aby bylo dosaženo požadovaných geometrií, pomocí XFOIL získání 2-D aerodynamických charakteristik aerofoilů, pomocí Glauert III vedle základních výpočtů získání aerodynamických koeficientů rozložených podél celého povrchu a řešení pro celkové síly působící na model. Závěrem je provedena zkouška modelu aerodynamického tunelu pro ověření výpočetní části.
Thermal conductivity of Cu7.2Ni1.8Si1Cr copper alloy produced via SLM and ability of thin-wall structure fabrication
Mašek, Jakub ; Koutný, Daniel ; Popela, Robert
Selective Laser Melting (SLM) as part of the Additive manufacturing industry is a metal printing technology that is considered promising to address the thermal integrity defects of a Heat Switch – the space technology currently under development. However, no thermal conductivity data of SLMed copper alloy Cu7.2Ni1.8Si1Cr are freely available. Therefore, three parts were fabricated and tested in an experimental thermo-vacuum chamber to reveal the material thermal conductivity. The samples analogous to the Heat Switch components were: a disk with inner holes and two cylinders with thin-wall web of 0.325 mm and 1.625 mm. Based on the previous experience with the copper alloy, fabrication was successfully processed with up to 5 % dimensional accuracy according to CAD model. The thermal conductivity evaluation process was improved by the implementation of heat transfer by radiation and the calculated thermal conductivity of SLMed Cu7.2Ni1.8Si1Cr was 3.4 times lower than the value of bulk material AMPCOLOY 944 with a similar chemical composition.
Modern flow visualization techniques
Pištěcká, Kateřina ; Koutník, Tomáš (referee) ; Popela, Robert (advisor)
The subject of this bachelor thesis is an overview of the flow visualization methods applied in the wind tunnels and fly tests. An overview of flow visualization methods is presented in the first part of the work. The particular methods are presented and evaluated with respect of its complexity, requirements on the instrumentation and expanses. The pros and cons are mentioned for each method finally. The second part of the work deals with selection of the flow visualization method suitable for application in the wind tunnel of the Aeronautical department of the VUT Brno.

National Repository of Grey Literature : 45 records found   1 - 10nextend  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.