O desenvolvimento de tecnologia na área de turbomáquinas é essencial ao desenvolvimento da indústria nacional e o Laboratório de Engenharia Ambiental e Térmica da Escola Politécnica da Universidade de São Paulo tem compreendido ações para este propósito. Este trabalho tem por objetivo desenvolver um compressor para uma turbina a gás de pequeno porte de 500 kW, primeiro passo para o projeto e construção da turbina como um todo. A partir da análise do ciclo termodinâmico e da análise de adimensionais, o tipo de compressor a ser utilizado foi determinado. Optou-se pelo projeto de um compressor centrífugo. Iniciou-se o projeto através de análise e correlações unidimensionais com previsão de desempenho, definindo algumas geometrias iniciais a serem avaliadas nas fases seguintes. Realizou-se a análise bidimensional do impelidor com a ferramenta computacional Vista TF que utiliza o método de curvatura de linhas de corrente. Por fim, a geometria tridimensional foi definida com uso de simulações de dinâmica de fluidos computacional. De acordo com as simulações, o compressor projetado tem desempenho condizente com os requisitos impostos. / Technology development in turbomachinery is essential to the national industry development and the Laboratory of Environmental and Thermal Engineering of the Polytechnic School of the University of São Paulo is engaged on this purpose. This work intends to design a compressor for a small 500 kW gas turbine, the first step in the whole turbine design and construction. The compressor type was determined from thermodynamical cycle and adimensional analysis. The centrifugal type compressor was chosen. The design was initialized using one-dimensional analysis and correlations with performance prediction models, defining initial geometries to be evaluated in the upcoming design phases. The impeller was analyzed with a two dimensional computational tool named Vista TF, which uses the streamline curvature method. The tridimensional geometry was defined using computational fluid dynamics. According to the simulations, the design compressor performs satisfying the imposed requirements.

O desenvolvimento de tecnologia na área de turbomáquinas é essencial ao desenvolvimento da indústria nacional e o Laboratório de Engenharia Ambiental e Térmica da Escola Politécnica da Universidade de São Paulo tem compreendido ações para este propósito. Este trabalho tem por objetivo desenvolver um compressor para uma turbina a gás de pequeno porte de 500 kW, primeiro passo para o projeto e construção da turbina como um todo. A partir da análise do ciclo termodinâmico e da análise de adimensionais, o tipo de compressor a ser utilizado foi determinado. Optou-se pelo projeto de um compressor centrífugo. Iniciou-se o projeto através de análise e correlações unidimensionais com previsão de desempenho, definindo algumas geometrias iniciais a serem avaliadas nas fases seguintes. Realizou-se a análise bidimensional do impelidor com a ferramenta computacional Vista TF que utiliza o método de curvatura de linhas de corrente. Por fim, a geometria tridimensional foi definida com uso de simulações de dinâmica de fluidos computacional. De acordo com as simulações, o compressor projetado tem desempenho condizente com os requisitos impostos. / Technology development in turbomachinery is essential to the national industry development and the Laboratory of Environmental and Thermal Engineering of the Polytechnic School of the University of São Paulo is engaged on this purpose. This work intends to design a compressor for a small 500 kW gas turbine, the first step in the whole turbine design and construction. The compressor type was determined from thermodynamical cycle and adimensional analysis. The centrifugal type compressor was chosen. The design was initialized using one-dimensional analysis and correlations with performance prediction models, defining initial geometries to be evaluated in the upcoming design phases. The impeller was analyzed with a two dimensional computational tool named Vista TF, which uses the streamline curvature method. The tridimensional geometry was defined using computational fluid dynamics. According to the simulations, the design compressor performs satisfying the imposed requirements.

No description available.

In axial flow compressors and fans, the stable working range is restricted by the so called stall line where operation may become unstable and simultaneously a short fall in compressor performance appears. Stall margin improvement has been a major task and experimental observations over the last two decades have shown that modifying the shape of the outer annulus wall, above the tips of rotor blades, is effective in delaying the onset of stall to lower mass flow rates. A wide variety of wall modifications or casing treatments have been tried with a range of stall flow improvement which can amount to about 20% .(of the stalled flow) An alternative technique for stall margin improvement in a single stage axial flow machine has been studied and results will be described in the present thesis. The technique for delaying stall involves a large scale treatment to the outer casing of the compressor which extends partly over and mainly upstream of the rotor. The operating principle appears to be that as the flow is reduced towards the stall point some radially unbalanced cells are transported from the blade tips where they are collected in the treatment , turned by the treatment vanes , and re-introduced to the main flow upstream of the rotor. A rotor with and without outlet stators has been tested ( and also with and without casing treatment) over a range of speeds and flow conditions. Also the flow condition inside the recessed casing has been simulated by means of an existing computer code known as PHOENICS.

During hot days, gas turbine power output deteriorates significantly. Among various means to augment gas turbine output, inlet air fog cooling is considered as the simplest and most costeffective method. During fog cooling, water is atomized to micro-scaled droplets and introduced into the inlet airflow. In addition to cooling the inlet air, overspray can further enhance output power by intercooling the compressor. However, there are concerns that the water droplets might damage the compressor blades and increased mass might cause potential compressor operation instability due to reduced safety margin. Furthermore, the two-phase flow thermodynamics during wet compression in a rotating system has not been fully established, so continued research and development in wet compression theory and prediction model are required. The objective of this research is to improve existing wet compression theory and associated models to accurately predict the compressor and the entire gas turbine system performance for the application of gas turbine inlet fog cooling. The following achievements have been accomplished: (a) At the system level, a global gas turbine inlet fog cooling theory and algorithm have been developed and a system performance code, FogGT, has been written according to the developed theory. (b) At the component level, a stage-stacking wet compression theory in the compressor has been developed with known airfoil configurations. (c) Both equilibrium and non-equilibrium water droplet thermal-fluid dynamic models have been developed including droplet drag forces, evaporation rate, breakup and coalescence. A liquid erosion model has also been developed and incorporated. (d) Model for using computational fluid dynamics (CFD) code has been developed to simulate multiphase wet compression in the rotating compressor stage. In addition, with the continued increase in volatility of natural gas prices as well as concerns regarding national energy security, this research has also investigated employing inlet fogging to gas turbine system fired with alternative fuels such as low calorific value synthetic gases. The key results include discovering that the saturated fogging can reduce compressor power consumption, but overspray, against conventional intuition, actually increases compressor power. Nevertheless, inlet fogging does increase overall net power output.

The thesis is about investigating the inlet and outlet pipes effect on the compressors measured performance. From measurements made in a gas stand, a thermodynamic model is to be created and the compressor efficiency further investigated. The temperatures and pressures entering and leaving the compressor does not have to be the same as the temperatures measured in the gasstand, because of the thermodynamics of the pipes that connects the measurement equipment and the compressor. During a gasstand test the turbocharger is connected in a test bench, it is connected with pipes on both the compressor and turbine side, to simulate the hot exhaust gases from the car engine and the pressure increase over the compressor. The air entering and leaving the turbocharger through the different pipes is controlled and all the entering and leaving temperatures and pressures are measured. Gasstand data from different tests are available during the thesis, one specific turbocharger is used as references during the modeling. Models of the inlet and outlet pipes are created and connected to a compressor model. The model is controlled to give the same mass flow as the measured data, to ensure that the work cycle is followed. The effects of the non ideal inlet and outlet pipes on measured compressor efficiency is studied with help of this model and the main impacts on the measured compressor efficiency are discovered. The result shows that the measured values used to calculate the compressor efficiency could change, depending on the measurement positions on the inlet and outlet pipes.

Thesis (M.S. in Operations Research) Naval Postgraduate School, March 1997. / Thesis advisor, Garth V. Hobson. Includes bibliographical references (p. 59). Also available online.

Deficient performances of turbocharger compressors inside turbo-charged engines limit the behaviour of the drive train. This problem has shifted the design space for compressors towards their performance at part-speed and low-flow conditions. The most dominant feature of these flow conditions is inlet recirculation. It causes a large portion of flow to be expelled through the rotor inlet, creating a blockage ring on the casing. While on the one hand, inlet recirculation is the main loss-source at low-speed and low-flow within centrifugal compressors, on the other hand, it also keeps the compressors functioning because it reduces incidence. This thesis aimed towards increasing the understanding of inlet recirculation, with the scope on improving the part-speed, low-flow performance of automotive turbocharger compressors. The phenomenon was investigated regarding its key features, the conditions at which it occurs and its impact on performance. Furthermore, a reduced order model was derived and the influence of the tip gap size as a design parameter was analysed. The research was carried out on an automotive turbocharger compressor which was investigated experimentally and numerically. Inlet recirculation is a phenomenon which takes place in the tip region of the rotor, extending far downstream and far upstream of the leading edge. The flow within the recirculation bubble features a strong positive swirl component, affecting the work input into the machine. The phenomenon is non-periodic in a time-averaged sense. An investigation of the rotor flow-field regarding inlet recirculation, carried out for the first time, revealed that the starting point of inlet recirculation is located far inside the rotor passage. An analysis based on mass, momentum and energy allowed the derivation of a low-order model to account for inlet recirculation in preliminary design. In the compressor map, inlet recirculation was present over 40% of the map width at low speeds. It maintained its presence with increasing rotor speed beyond the point where the inlet flow became transonic. The losses in the inlet recirculation zone were shown to be up to 35% of the total compressor loss at low speed. A loss analysis showed that inlet recirculation was the main loss source at low-flow conditions. The tip clearance study showed that the size and intensity of inlet recirculation was independent of the tip gap size. Efficiency gains due to reduced tip leakage were marginalised by the presence of inlet recirculation but the rotor maintained enhanced pressure rise capabilities for reduced tip gap sizes.

Mines in general, make use of compressed air systems for daily operational activities. Compressed air on mines is traditionally distributed in two typical fashions. Firstly, direct pipe feed systems for single shafts or compressed air ring networks where multiple shafts are supplied with compressed air from an integral system. These compressed air networks make use of number compressors feeding the ring from various locations in the network. While mines have sophisticated control systems to control these compressors they are not dynamic. Compressors are selected on static priorities for a chosen time period of the day. While this is acceptable for some days it is not always the ideal solution. The compressed air demand of the ring is dynamic and it is difficult to estimate the future need of the system. The Dynamic Compressor Selector (DCS) is described as a solution to this problem. DCS is a computer based control system featuring a Graphical User Interface (GUI). The aim of DCS is to dynamically calculate a control pressure set-point, given the demand for compressed air as well as choose the optimal compressors to supply the given compressed air. This will reduce the power requirement of the compressed air ring as well as reduce compressor cycling. DCS was implemented and tested on a single mine compressed air system. Achieved results were 1.8 MW in electricity savings as well as the added benefit of reduced cycling. This saving results in a cost saving of R3.7 million per annum. The problems and shortfalls of the system are also discussed as well as possible future directions for moving forward. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

The generation of compressed air comprises 20% of the total electricity usage in the mining industry, although compressed air is often seen as a free source of energy. There are however significant costs associated with generating compressed air and maintaining a compressed air system. There are several methods to optimise the electricity used to generate compressed air. The focus of this study is on one of these methods – the implementation of a dynamic air compressor selector. A Dynamic Compressor Selector (DCS) system was developed to fulfil this purpose. DCS is a system that combines demand- and supply-side management of a compressed air network. DCS calculates a pressure set point for compressors and schedules the compressors according to the demand from the end-users. End-users include shafts, plants, workshops and smelters. DCS takes all of the compressors and end-users into consideration while doing the calculations. This dissertation focuses on the DCS implementation process and on the problems encountered by previous authors while implementing the DCS technology. Additional problems were encountered while the DCS technology was implemented. DCS was however still successfully implemented. This study will expand the implementation procedure to ensure that the technology can be implemented successfully in the future. DCS was implemented at a platinum mine in South Africa where it was able to calculate pressure set points for the compressors. DCS was able to accurately match the supply of, and demand for compressed air closely, resulting in lower overall compressed air usage. DCS improved compressor scheduling and control, limiting compressor cycling. Improved compressor scheduling and control resulted in significant decreases in the electricity used to generate compressed air at the mine. A target average evening peak clip of 2.197 MW was simulated, set and achieved. Evening peak clip power savings in excess of an average of 3 MW were achieved. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015