The effect of partial rotor-to-stator rubbing is investigated both experimentally and analytically. It is found that due to rubbing the measured vibration signal is distorted showing a flattened portion in the waveform. Spectral analysis indicates that the synchronous component is generally attenuated as a result of rubbing-introduced-friction. It is also indicated that light rubbing induced vibrations are characterized by harmonics at frequencies equal to 1x rev., 2x rev., and 3x rev. Whereas, severe rubbing is identified experimentally by a spectrum containing subharmonics at 1/3 and 2/3 of the rotational frequency. Because of the stiffening effect of rubbing on the rotor, the resonance frequency increases. In general, the analytical results show good agreement with experimental data.
A blade-to-blade inverse design procedure is presented for use in a quasi-3-D design system for multistage axial flow compressors. The procedure is applicable to transonic rotor and stator airfoil sections along axisymmetric stream surfaces. It accounts for the streamtube thickness and radius variations, and can be used in the analysis, fully inverse, and mixed inverse modes. Steady state Euler equations are implemented and formulated in terms of density and local displacement normal to streamline as dependent variables. Three test cases are presented in this paper to illustrate the application of this inverse design technique for optimizing rotor and stator airfoils of highly loaded, high pressure ratio compressor stages. These test cases demonstrate the capability of this procedure to optimize airfoil geometry for minimizing shock and diffusion losses without compromising the airfoil structural integrity.
In this work, the performance of a two-shaft industrial gas turbine engine inspired by SGT-750, one of best technology at Siemens, is analyzed thermodynamically and economically. The modelling and analyzing process for the proposed system was executed through a software package called IPSEpro and validated with manufacturers’ published data. Exergy analysis, based thermodynamics laws with mass conservation, provides valuable information about locations, magnitudes and types of wastes energy in the thermal systems. Exergoeconomic analysis, the amalgamation of exergy with economics, is useful tool to appraise the gas turbine engine cost-effectiveness. The Specific Exergy Costing method is selected in exergoeconomic evaluation because it is the most widely used reported in the literature and provides reliable results. The performance of a gas turbine engine was investigated for different load variation and climatic conditions. The result shows that the main source of irreversibilities take place in the combustion chamber, compressor and high-pressure turbine, respectively, which constitute to about 96 % of total exergy destruction. The exergetic efficiency and exergy loss rate of the proposed system are about 38.4% and 11.8% respectively. The combustion chamber has the highest value of cost (1312.9 $/h) among other components and the source losses may attribute to the component performance. The production cost of the gas turbine engine based on exergoeconomic evaluation is 12.1 US$/GJ.
In this study, the performance of several gas turbine engines has been investigated using computational modelling based on the actual manufacturer's data. Further, the study focuses on evaluating the impact of varying the configuration of the compressor on overall engine performance based on the first and second laws of thermodynamics. The results confirm that the main source of irreversibilities occurs in the combustion chamber in all cases. The exergetic efficiency of the gas turbine engine significantly varies with compressor configurations, type of compressors, load variation, climatic condition, and isentropic efficiency. The engine capacity and high‐pressure turbine inlet temperature govern the gas turbine performance, and higher values are more favourable. The gas turbine exergetic efficiency drops off when the power setting adjusted at part‐load and at high ambient temperature. The most optimal gas turbine performance is located at the single axial compressor case, followed by the axial‐centrifugal compressor and then the centrifugal–centrifugal compressor.
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