CAUSALITY DIAGRAM BASED SAFETY ANALYSIS OF MICRO TURBOJET ENGINE

An improved safety analysis based on the causality diagram for the complex system of micro aero-engines is presented.The study is examined by using the causality diagram in analytical failure cases due to rupture or pentration in the receiver of micro turbojet engine casing,and the comparisons are also made with the results from the traditional fault tree analysis.Experimental results show two main advantages：（1）Quantitative analysis which is more reliable for the failure analysis in jet engines can be produced by the causality diagram analysis;（2）Graphical representation of causality diagram is easier to apply in real test cases and more effective for the safety assessment.

Numerical Simulation and Performance Analysis on Windmill Starting Process of Small Turbojet Engine

A new simulation strategy is proposed for the starting process of missile turbojet engine windmill. The starting process of windmill before ignition is simulated using a radial basis function neural network (RBFNN) , and the acceleration process after ignition which model is a set of nonlinear equations is solved using a particle swarm optimization (PSO) algorithm. The introduction of PSO helped to tackle the problem of divergence caused by traditional iteration methods. The calculated result is in a great agreement with test data, which shows that the presented model has a high accuracy. The starting processes are simulated at different ignition times, and the results are analyzed synthetically. The analysis shows how the ignition time affects the starting performance of engine windmill. The method offers a useful tool for ignition time optimization as well as engine starting performance analysis.

LMI-BASED AERO-ENGINE CONTROLLER DESIGN

The problem of analysis and synthesis of robust control is addressed in this work. The approach transferring the robust control design into Linear Matrix Inequality (LMI) is provided. The LMI standard structure of robust controller is also given and the controller is obtained through solving three LMIs. As an example, a robust control law is designed to the twin-spool turbojet engine system using the given approach. The result shows that LMI approach is feasible.

Entransy analyses of the thermodynamic cycle in a turbojet engine

The analysis and the design of turbojet engines are of great importance to the improvement of the system performance.Many researchers focus on these topics,and many important and interesting results have been obtained.In this paper,the thermodynamic cycle in a turbojet engine is analyzed with the entransy theory and the T-Q diagram.The ideal thermodynamic cycle in which there is no inner irreversibility is analyzed,as well as the influences from some inner irreversible factors,such as the heat transfer process,the change of the component of the working fluid and the viscosity of the working fluid.For the discussed cases,it is shown that larger entransy loss rate always results in larger output power,while smaller entropy generation rate does not always.The corresponding T-Q diagrams are also presented,with which the change tendencies of the entransy loss rate and the output power can be shown very intuitively.It is shown that the entransy theory is applicable for analyzing the inner irreversible thermodynamic cycles discussed in this paper.Compared with the concept of entropy generation,the concept of entransy loss and the corresponding T-Q diagram are more suitable for describing the change of the output power of the analyzed turbojet engine no matter if the inner irreversible factors are considered.

Optimization of gas turbines for sustainable turbojet propulsion

Gas-turbines are widely used to power aero planes because they are light,compact with a high power-to-weight ratio.In the turbo jet engine,the main operating variables are:compressor pressure ratio rp and turbine inlet temperature(TIT).These variables affect the specific thrust and specific fuel consumption(SFC),which represent the main performance parameters.In addition to the analytical work,a computer program of the General Algebraic Modeling System(GAMS)was used for analysis and optimization.The analysis shows that the specific thrust strongly depends on turbine inlet temperature(TIT),where a 10%decrease in TIT results in 6.7%decrease in specific thrust and 6.8%decrease in SFC.Furthermore,the value of optimum pressure ratio rf for maximum specific thrust increases with TIT.A 10%decrease from design TIT results in 11.43%decrease in rf.The value of optimum pressure ratio for the turbojet engine operating at Ma=0.8 and altitude Alt=13000 m,and TIT=1700 K was found to be 14.&2015 National Laboratory for Aeronautics and Astronautics.Production and hosting by Elsevier B.V.

Numerical Study of Effect of Compressor Swirling Flow on Combustor Design in a MTE

An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics(CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The distributions of air mass and the Temperature Pattern Factor(as: Overall Temperature Distribution Factor-OTDF) in outlet are investigated with two different swirling angles of compressed air as 0° and 15° in three combustors. The results show that the influences of swirling flow on the air distribution and OTDF cannot be neglected. Compared with no-swirling flow, the air through outer liner is more, and the air through the inner liner is less, and the pressure loss is bigger under the swirling condition in the same combustor. The Temperature Pattern Factor changes under the different swirling conditions.