Numerical Simulation And Optimization Of Whole Conditions Of Biogas Thermal Turbine

The externally fired biogas micro-gas turbine,which replaces the combustion of the regenerated Brayton cycle with high-temperature regenerator and adds an externally combustion outside the thermodynamic cycle,realizes the micro-turbine’s indirect heating.It is effective to avoid the damage and corrosion on rotational parts by impurities（H₂S）in the biogas,besides,reduces the quality requirements of biogas（simplified purification process）,and achieves that the low-qulity biogas can be used to generate electricity directly.However,at present,few domestic researchs for externally combustion gas turbine,especially in miniaturized,modular externally fired biogas micro gas turbine generator sets.Based on the above background,this thesis focuses on externally fired biogas micro-turbine,its cycle characteristics was presented,completed the aerodynamic design,three dimensional flow field analysis of full operating conditions and blade profile optimization,which provides technical support and theoretical basis for the design and development of the externally fired micro-gas turbine generator sets.The regenerative thermodynamic cycle and external fired thermodynamic cycle are established respectively by Aspen Plus,it compares the analysis of pressure ratio and turbine inlet temperature effect on the net output power and the cycle efficiency separately,the suitable cycle model is chosed for the biogas turbine design.In addition,the cycle characteristics of the 45kW class externally fired biogas micro-gas turbine ere studied,the cycle pressure ratio and turbine inlet temperature are determined.Then,the design parameters of the turbine are obtained.The reasonable zone of the design scheme of the biogas turbine is determined by the screening method,and the design scheme of the biogas turbine is determined according to detailed calculation,Then,the main aerodynamic parameters and structural parameters of the turbine are obtained by detailed thermodynamic calculation.With the aid of AxSTREAM build the through-flow model,and the aerodynamic parameters and structure parameters of the turbine are obtained by one dimensional aerodynamic calculation accompanied by DOE optimization,two dimensional aerodynamic computation and DOE optimization..The numerical simulation of the turbine flow field is completed,which obtained by the aerodynamic design.The performance parameters and flow field characteristics of the turbine are presented,and the rate of flow,efficiency and power characteristic curve of the whole conditions are given,and the optimization direction of gas turbine is given.A parametric model of biogas turbine is established,the optimization variables and the sample database are completed.By means of artificial neural network fitting algorithm to get the approximate fitting relationship optimization variables and objective variables（total-total efficiency）,combined with the optimization of genetic algorithm to get the optimization solution.The flow,efficiency and power characteristic curves of the turbine are compared and analyzed before and after optimization,and the improvement of the performance and the flow characteristics of the turbine are given,the optimization conclution is provided.