CFD Application for Gas Turbine Combustion Simulations

The current chapter presents the use of computational fluid dynamics (CFD) for simulating the combustion process taking place in gas turbines. The chapter is based on examples and results from a series of applications developed as part of the research performed by the authors in national and European projects. There are envisaged topics like flame stability, pollutant emission prediction, and alternative fuels in the context of aviation and industrial gas turbines, growing demands for lower fuel consumption, lower emissions, and overall sustainability of such energetic machines. Details on the available numerical models and computational tools are given along with the expectation for further developing CFD techniques in the field. The chapter includes also some comparison between theoretical, numerical, and experimental results

Energy conversion and efficiency in turboshaft engines

This paper discusses the methods of energy conversion in a turboshaft engine. Those methods cover the thermodynamic cycle and the engine performances, the possible energy sources and their impact on environment as well as the optimal solutions for maximum efficiency in regards to turbine design and application. The paper also analyzes the constructive solutions that limit the efficiency and performances of turboshaft engines. For the purpose of this paper a gas-turbine design task is performed on an existing engine to appreciate the methods presented. In the final part of this paper it is concluded that in order to design an engine it is necessary to balance the thermodynamic aspects, for maximum efficiency, and the constructive elements, so that the engine can be manufactured

Application of a Performance-Improvement Method for Small-Size Axial Flow Turbines

As a main component of most gas-turbine engines, the axial flow turbines have been in a process of continuous improvement, reaching high efficiencies and reliability. A well-known drawback of these systems is the rapid decrease in performance when operating at lower than nominal conditions. Thus, a novel performance-enhancement method for axial turbines operating at partial loads has been previously proposed and numerically characterized. In this paper, one applies the aforementioned method for a smaller size axial flow turbine, part of a gas-generator assembly for a microjet engine, to determine, by the use of CFD analysis, the influence of the system at different partial regimes across the working line. A logical scheme based on iterative steps and multiple numerical simulations is also used to determine the engine response to the injection of compressor bleed air into the turbine passages. The results show, as determined in the previous study, that the generated power can be increased for all partial regimes, with the influence being more noticeable at higher regimes, leading to a reduction in fuel consumption in order to achieve the same regimes

Computational fluid dynamics calculus and analysis for gas and water turbines

The paper presents the utilization of Computational Fluid Dynamics for calculating the flow through turbines. The first and most extended part of the paper is focused on gas turbines where the simulations are very precise and can be successfully used even for optimization of blade geometry. Flow details and results for an axial turbine are presented along with a proposal of optimization algorithm. The second part of the paper is dedicated to water turbines and there is presented the calculus realized for a kinetic water turbine. I this case, the flow around the turbine blades is presented and some data about the predicted performances along with many ways for improving the simulations. The conclusions of the paper are related to similarities and differences between the two types of simulations and to the many ways of using these simulations for practical applications

Computational fluid dynamics calculus and analysis for gas and water turbines

The paper presents the utilization of Computational Fluid Dynamics for calculating the flow through turbines. The first and most extended part of the paper is focused on gas turbines where the simulations are very precise and can be successfully used even for optimization of blade geometry. Flow details and results for an axial turbine are presented along with a proposal of optimization algorithm. The second part of the paper is dedicated to water turbines and there is presented the calculus realized for a kinetic water turbine. I this case, the flow around the turbine blades is presented and some data about the predicted performances along with many ways for improving the simulations. The conclusions of the paper are related to similarities and differences between the two types of simulations and to the many ways of using these simulations for practical applications

Axial Turbine Performance Enhancement by Specific Fluid Injection

Extensively used in modern gas turbine engines in various applications, ranging from aerospace, marine and terrestrial propulsion to power generation and gas pumping, the axial flow turbines have been continuously updated and are now capable of high performances and reliability. One drawback that has not yet been resolved is the poor performance of the axial turbines at lower- than-nominal regimes. To solve these shortcomings, a new method to improve the performances at partial regimes by specific fluid injection is proposed in this paper. The influence of the injection system is determined by conducting a numerical analyze, studying the influence of different parameters (i.e., number, dimensions and position of the of injection orifices) on the overall performances of the turbine. The study is completed on a single stage 1300 KW turbine with the injection system being applied to different power settings across the working line. The results show that the power generated by the turbine can be enhanced by as much as 30% for different configurations of the injection system (i.e., high number of small size orifices) and different partial regimes

Performance estimation on micro gas turbine plant recuperator

In order to accomplish a thermodynamic analysis of a micro gas turbine plant, while satisfying conditions related to different configurations, different input data sets and a series of imposed thermodynamic parameters, assumptions are necessary regarding the individual performance of the components, for enabling the correlation of overall performance with the performance of the components. The use of a recuperator, even if it can improve a micro gas turbine cycle efficiency, by reducing the fuel consumption for an imposed turbine inlet temperature, will induce a pressure loss on the hot and cold sections, with possible negative influence on the cycle efficiency. In order to investigate this pressure loss, a numerical study was conducted on several cases, by modifying the geometry of a simplified recuperator, using as input a reference micro gas turbine thermodynamic cycle. The comparison between the different results led to the quantification of recuperator’s performance as a function of its geometry