<p>Rising fuel costs and growing environmental concerns have forced gas turbine engine manufacturers to place high value on reducing fuel burn. This trend has pushed compressor technology into new design spaces that are not represented by historical experience. Specifically, centrifugal compressor diffusers are trending toward higher pressure recovery and smaller diameters. The internal fluid dynamics in these new flow regimes are not well understood and additional study is necessary. This work outlines detailed experimental and numerical observations of the flow field through a vaned diffuser for aeroengine applications.</p> <p>The experimental data consist of extensive Laser Doppler velocimetry measurements of the unsteady velocity field from the impeller trailing edge through the majority of the diffuser passage. These data were obtained non-intrusively and yielded all three components of the velocity vector field at approximately 2,000 geometric points. The correlation between fluctuations in the three velocity components were also observed at several key locations to determine the components of the local Reynolds stress tensor.</p> <p>These data indicated a jet/wake profile at the impeller exit represented by a consistent velocity deficit region from hub to shroud adjacent to the suction surface of the passage. This region was more prevalent adjacent to the splitter blade. The unsteady fluctuations due to the propagation of the jet and wake through the diffuser passage persist to 40% downstream of the throat. A complex secondary flow field was also observed with large axial velocities and a passage-spanning vortex developing through the diffuser passage. The velocity data and total-pressure data indicated a region of flow separation developing along the pressure surface of the vane near the hub due to the unsteady propagation of the jet and wake flow through the diffuser. Although this region was stable in time, its development arose due to unsteady aspects of the flow. Finally, the strong interconnection between the jet and wake flow, unsteady fluctuations, secondary velocities, incidence, and flow separation was demonstrated. </p> <p>Computationally, a “best-practice” methodology for the modelling of a centrifugal compressor was developed by a systematic analysis of various turbulence models and many modelling features. The SST and BSL-EARSM turbulence models with the inclusion of fillets, surface roughness, and non-adiabatic walls was determined to yield the best representation of the detailed flow development through the diffuser in steady (mixing-plane) simulations. The accurate modelling of fillets was determined to significantly impact the prediction of flow separation with the SST turbulence closure model. Additionally, the frozen rotor approach was shown to not accurately approximate the influence of unsteady effects on the flow development.</p> <p>Unsteady simulations were also compared to the detailed experimental data through the diffuser. The BSL-EARSM turbulence model best matched the experimentally observed flow field due to the SST model’s prediction of flow separation in the shroud-pressure side corner of the passage. In general, lower levels of axial velocity were predicted numerically that resulted in less spanwise mixing between the endwall and freestream flows. Additionally, the turbulent kinetic energy levels in the computational results showed little streamwise variation through the vaneless and semi-vaneless space. The large variation observed experimentally indicated that the production and dissipation of turbulent kinetic energy through this region was not accurately predicted in the two turbulence models implemented for the unsteady simulations.</p>

Goal of this master’s thesis is design of trailer compressor intended for construction work. Part of this work is conducting analysis, dealing with history, technical possibilities and contemporary trends in using compressors. Second part contains solution based on the conducted research with regards to meet all the functional, technical, esthetic and ergonomic requirements.

The thesis pursues a design of mechanism for controlling the amount of air sucked by a turbocharger compressor. In the first part, there is a brief description of a turbocharger and its characteristics, in the second part the usual regulation methodologies are presented. Third, the main part describes the creation of the mechanism from concept drafts and their comparison, through the kinematic and force analysis of control parts, to the complete packaging a connection to the compressor housing. The fourth part is dedicated to the mechanism analysis in the terms of ability to perform as required.

The topic of this diploma thesis is CFD simulation of flow inside CO2 semi-hermetic reciprocating compressor Stream manufactured by Emerson. The goal of this thesis is to analyze critical points inside the compressor with regard to excessive entrainment of oil by flowing refrigerant by means of CFD simulation using ANSYS CFX. Simulation for both single-phase and two-phase flow is part of the thesis and results from them are analysed.

This thesis is concerned with the calculation of the power turbine. This turbine should be used in the automatic drive of the compressor used for compression of natural gas in compressor stations. Flight engine aeroderivate from the Rolls-Roye company, type RB211-22B, was used as gas generator. The main aim of the thesis is to summarize of the base atributes of the combustion turbines and aeroderivates. They are used for automatic engine, application a thermodynamic calculation of the power turbine, for reaction stage and basic strength calculations.

Tahle práce se zaměřila na aerodynamickou analýzu principů zvyšování pumpážních záloh. V první kapitole jsou popsány kompresory leteckých motorů a zavedeny potřebné znalosti kompresorových charakteristik a proti-pumpážních zařízení. V druhé kapitole se nachází detailní popis CFD modelu, jeho nastavení, citlivostní analýzy sítě a korelace výsledků s experimentálním měřením. V třetí kapitole jsou popsány data neupraveného kompresoru a jsou zde popsány problematická místa první stupně kompresoru z pohledu proti-pumpážních zařízení. Ve čtvrté kaptiole jsou popsány CFD výsledky z analýz jednotlivých proti-pumpážních zařízení a také popis jejich optimalizace. Práce je zakončena srovnáním jednotlivých zařízení pomocí dvou objektivních kritérií.

<div>A common assumption often made of dynamic compressors is that they are considered adiabatic, due to the fast-moving flow passing through the turbomachine and the small amount of any heat transfer relative to the large amount of work transferred to/from the flow. This research investigation combined the use of experimental measurements and computational simulations to take a deeper look into the implications that arise from applying this adiabatic assumption or neglecting heat transfer within a high-speed, multi-stage, axial compressor.</div><div><br></div><div>Preliminary testing of the Purdue 3-Stage (P3S) Axial Compressor Research Facility indicated the presence of heat transfer through stagnation temperature rises across stationary blade rows and higher than expected temperatures on the outside of the aluminum compressor casing, particularly in the front stages. Further experiments performed on the PAX200 compressor in the P3S facility involved a combination of surface temperatures, heat fluxes, and flow stagnation temperatures within the shrouded stator cavities and flowpath. These measurements confirmed that heat transfer was present throughout the stationary components (stators and casing) of the compressor and showed that they could noticeably affect the thermal flow properties within the compressor.</div><div><br></div><div>The influence of the heat transfer through these components was further explored through computational simulations, which showed the importance of incorporating conjugate heat transfer into the model and applying the correct thermal boundary conditions on the outside of the casing. Additionally, the effects on the spanwise temperature of the flow through increased spanwise mixing, convection, and different geometric and material properties of the casing were also explored. Overall, this investigation seeks to establish a correct thermal boundary condition and approach for validation of computational model. It also aims to reconcile the differences between computational models and experimental data by quantifying the impact that heat transfer has on isentropic efficiency for diabatic compressors.</div>

This master’s thesis deals with kinematics model of blade rotating mechanism of turbocharger, which is called as VNT (“Variable nozzle turbine”). The first section treat of turbochargers generally, why we use them, summary description of construction and parts. In the next section deals with supercharge control, about types of controlling and theirs principles, of their vantages or disadvantages and comparison. Following section is about building kinematics model in software ADAMS. First step is analytics solving of mechanism, because it was necessary for parametric model. After this is described main model building. In the last section is kinematics model used on real turbocharger for checking results.

This diploma thesis is dedicated to a design of a reversing turbo-compressor. The thesis is divided into several parts. The introductory part includes the relevant theory and categorization of turbomachines. The second part describes the storage system the machine is designed for. A separate chapter is devoted to other examples of possible use of this machine. The next chapter provides a detail description of modes and individual parts of the machine. The most comprehensive chapter is then devoted to the design of the compressor, turbine calculation and design of integrated gearbox. The thesis also includes an annex, which contains the technical documentation.

This diploma thesis is focused on performance options for turbocharged 1.2 litre spark ignition engine. First of all, couple of engine variants are compared and the most suitable one is chosen. Production turbocharger is determined upon the calculation of compressor parameters. Simulation in Lotus Engine Simulation and GT-Power is done to confirm co-operation of turbocharger with engine. Two stage serial turbochargers are also compared and the most effective pair is chosen for simulation. Research through the possibilities for increase the power output and the detail focus on turbochargers is also part of this thesis.