Munzer S. Y. Ebaid

Modeling and Simulation of a Gas Turbine Engine for Power Generation

The gas turbine engine is a complex assembly of a variety of components that are designed on the basis of aerothermodynamic laws. The design and operation theories of these individual components are complicated. The complexity of aerothermodynamic analysis makes it impossible to mathematically solve the optimization equations involved in various gas turbine cycles. When gas turbine engines were designed during the last century, the need to evaluate the engines performance at both design point and off design conditions became apparent. Manufacturers and designers of gas turbine engines became aware that some tools were needed to predict the performance of gas turbine engines especially at off design conditions where its performance was significantly affected by the load and the operating conditions. Also it was expected that these tools would help in predicting the performance of individual components, such as compressors, turbines, combustion chambers, etc. At the early stage of gas turbine developments, experimental tests of prototypes of either the whole engine or its main components were the only method available to determine the performance of either the engine or of the components. However, this procedure was not only costly, but also time consuming. Therefore, mathematical modelling using computational techniques were considered to be the most economical solution. The first part of this paper presents a discussion about the gas turbine modeling approach. The second part includes the gas turbine component matching between the compressor and the turbine which can be met by superimposing the turbine performance characteristics on the compressor performance characteristics with suitable transformation of the coordinates. The last part includes the gas turbine computer simulation program and its philosophy. The computer program presented in the current work basically satisfies the matching conditions analytically between the various gas turbine components to produce the equilibrium running line. The computer program used to determine the following: the operating range (envelope) and running line of the matched components, the proximity of the operating points to the compressor surge line, and the proximity of the operating points at the allowable maximum turbine inlet temperature. Most importantly, it can be concluded from the output whether the gas turbine engine is operating in a region of adequate compressor and turbine efficiency. Matching technique proposed in the current work used to develop a computer simulation program, which can be served as a valuable tool for investigating the performance of the gas turbine at off-design conditions. Also, this investigation can help in designing an efficient control system for the gas turbine engine of a particular application including being a part of power generation plant.

Optimization techniques for designing an inward flow radial turbine rotor

Abstract The choice of the principal dimensions of a turbine rotor for a given set of inlet design specifications can be found by solving aerodynamic equations. An analytical method is indeed difficult and can be very time consuming, especially if the complete procedure has to be repeated for different cases. In view of this, numerical optimization techniques can be a useful tool to problems involving a large number of variables. However, turbines commonly operate at high temperature and at high speeds, therefore the design process is an interactive one between the aerodynamic requirements and the mechanical, thermal limitations. This paper describes the complete design work of a turbine rotor based on using a nonlinear optimization technique to calculate the optimum principal dimensions of the rotor including optimum number of blades. Also, a prescribed mean stream velocity approach is used to determine the optimum axial length and the flow passage. For mechanical consideration, structure and thermal stresses and modal (vibration) analyses were carried out to satisfy design requirements.

Measurements of the laminar burning velocity for propane: Air mixtures

In this research, an experimental setup was built based on using K-type thermocouples inserted in a cylindrical vessel and coupled with a computer system to enable online reading of flame speed for propane-air mixtures. The work undertaken here has come up with data for laminar burning velocity of the propane-air mixtures based on three initial temperatures Tu = 300, 325 and 350 K, three initial pressures pu = 0.5, 1.0 and 1.5 bar over a range of equivalence ratios ϕ between 0.6 and 1.5. The results obtained gave a reasonable agreement with experimental data reported in the literature. Results showed that laminar burning velocity increases at low initial pressures and decreases at high pressures, while the opposite occurs incase of temperatures. The maximum values of the laminar burning velocity occur at T = 350 K, pu = 0.5 and ϕ = 1.0, respectively, while the minimum values of the laminar burning velocity occur at T = 300 K, pu = 1.5 and ϕ = 1.2. Also, the influence of flame stretching on laminar burning velocity was investigated and it was found that stretch effect is weak since Lewis number was below unity for all cases considered. Based on experimental results, an empirical equation has been derived to calculate the laminar burning velocity. The values of the laminar burning velocity calculated from this equation show great compatibility with the published results. Therefore, the derived empirical equation can be used to calculate the burning velocities of any gas of paraffin gas fuels in the range of mixture temperature and pressure considered.

Design of fuel control system using fuzzy logic for a pre-designed radial gas turbine driving directly high-speed permanent magnet alternator

Abstract Radial gas turbine of 50-kW power output coupled directly to a high-speed permanent magnet alternator could be a favourable option as an emergency power plant at areas suffering from severe disasters, such as earthquakes, floods and volcanoes. This study aims to use the results of the subtractive clustering algorithm and the least square estimation method to generate a fuzzy model of the pre-designed radial gas turbine system whereby the fuzzy model takes the fuel mass flow rate as an input, and gives the value of the gas turbine net work Wnet as an output. In addition, a suitable controller of the fuel mass flow rate is designed and analysed so that the speed of the gas turbine and the alternator is maintained at 42,000 rpm. A proportional derivative fuzzy controller was built and tested. Results illustrate that the proposed controller achieves the desired performance and stability, and showed the effectiveness of the approach. Conclusions of this study will constitute a base for further studies that could be made to enhance the performance of the proposed emergency power plant system.