Papers by Keyword: Combustion Chamber

Abstract: In this study, a CFD analysis to evaluate effect of combustion chamber geometry on in-cylinder fluid flows and equivalence ratio spread in a Direct Injection Spark Ignition Engine (DISI) during intake and compression stroke has been carried out. The analysis has been carried out using “STAR-CD es-ice” software for four piston top profiles viz., flat piston, flat piston with a centre bowl, dome piston with a central bowl and pentroof type piston with an offset bowl at an engine speed of 1000rpm. For meshing the geometric model, polyhedral trimmed cell are adopted. The solution is obtained by solving conservation of mass, momentum and energy equations using SIMPLE algorithm. From the results, it is found that for DISI engine, flat piston is best suitable.

Abstract: For the thermal load of a heavy vehicle is too high in plateau environment, based on Hiroyasu spray model and predictive combustion model, a turbocharged diesel engine model with environmental adaptive predictive ability was established. The experimental results of 3700m revealed that the simulation result relative errors were less than 5%. The research of combustion chamber temperature field was made. This method provides a fundamental basis for further design of the combustion chamber.

Abstract: With the convective heat transfer theory, numerical analysis of fluid-solid-heat coupling is implemented for the engine combustion chamber cooling structure based on finite element method and computational fluid dynamic method, thus to obtain valuable simulation results. Different components of the mesh generation method used which have different influences on the computational results are thought over during this analysis process, including different grid type, grid density and boundary layer meshes. Moreover, MPI parallel technique is also used to resolve the computation demands. The temperature distributions of the key parts in the cooling structure are investigated, which can be used as a significant reference for the thermal protection design of the engine combustion chamber.

Abstract: A nonlinear mathematical model with thermodynamic relations permitting an accurate assessment of the dynamic influence on performance is developed in this study. The model is used within the framework of engine design in the development stage and in implementation stage. The use of simulations can give an invaluable insight into transient response and control problems; a significant saving is achieved with minimum test bed hardware development without endangering an engine. Successful simulations have been carried out using the proposed algorithm; an application utilizing Object Orientated Programming (OOP) was developed. The results obtained by the present developed model are in fair agreement with available experimental data.

Abstract: Constant volume transparent test combustion chambers are extensively used for investigating injection and fuel burning properties of various combustion engines. Their configuration depends on the engine type and the research purpose. Material of components, shape and dimensions of the chamber and its parts, ease of use, accessibility, sealing and safety of the assembly are the parameters needed to be considered in designing the test cell. This paper explains, structural design of a test combustion chamber and its optical windows using finite element analysis of ANSYS 12.0 software for bearing high pressure variations and thermal shocks of combustion. It was designed for conducting CNG direct injection study on direct injection SI CNG engines for maximum design pressure of 100 bars. Optical diagnostic methods and high speed photography through quartz windows are used for the jet and flame developments. Satisfactory test results of the fabricated system proved that the finite element method can successfully be employed for design of such a system.

Abstract: One method of parametric design on combustion chamber is used in this paper. Several independent geometrical parameters of ω type and double swirl combustion chamber are brought forward. Different series of ω type and double swirl combustion chambers have been designed by using this method. The effect of the independent geometrical parameters on the performance of diesel engine has been studied by using CFD code AVL FIRE. According to this method of parametric design and calculation result, two pistons with ω type and double swirl combustion chamber has been designed with the target of the highest indicated heat efficiency. The test result shows that, contrasting with ω type chamber, BSFC and main combustion duration of double swirl combustion chamber is lower by 7.5 and 6.9 percent respectively, while indicated heat efficiency is 7.1 percent higher. And the calculation result has coherence with the experiment. It is proved that the method of parametric design on combustion chamber can satisfy the requirement of designing. At the same time, this method can be extended to design other combustion chambers.

Abstract: The major advantage of superplastic forming (SPF) technology is that it can form integral and complex components in simple operation, since it is possible to form one or more sheets of superplastic grade metal into single surface tools by relatively low gas pressure. Duplex steel contains two phases in nearly equal proportions which can suppress grain growth at a high temperature, like superplastic Ti-6Al-4V, and many duplex stainless steels with fine grained microstructures show superplastic behavior. In this study, superplastic forming technology was developed to fabricate a duplex stainless steel sheet for the outer surface of liquid propellant combustion chamber. Superplasticity of this alloy was investigated and forming methodology was analyzed and developed. The experimental results show a complex configuration of aerospace component was successfully fabricated by superpalstic forming of a sheet of duplex stainless steel.

Abstract: For the purpose of increasing applicability of combustion chamber simulation, computational domain, boundary condition, simplicity of complicated structures, mesh generation and physical parameters are investigated in this paper. An annular combustion chamber of some aero-engine is studied by means of predictive numerical simulation. The computational domain includes diffuser, swirler, inner flame tube, inner ring of combustion chamber and the flow channel of all the holes on the wall of flame tube. The film cooling holes row was simplified into a slit filled with porous media. Realizable k-turbulent model and non-premixed combustion model were adopted. Model of pressure atomization nozzle were calibrated and validated through inner nozzle flow property two-phase flow VOF model and experimental data. Physical parameters are express through polynomial functions. A commercial CFD code was adopted on a high performance computing cluster with parallel algorithm and the solving method are high-order discretization scheme. The velocity, pressure, temperature, fuel spray, density of fuel and productions, etc. are calculated and validated with the experimental data.

Abstract: All aircraft whatever they are; are regularly audited. These controls are mainly visual and external; other controls such as "major inspection" or "general revisions” are more extensive and require the dismantling of certain parts of the aircraft. Some parts of the aircraft remain inaccessible and are therefore more difficult to inspect (compressor, combustion chamber, and turbine). The means of detection must ensure controls either during initial construction, or at the time of exploitation of all the parts. The Non destructive testing (NDT) gathers the most widespread methods for detecting defects of a part or review the integrity of a structure. The aim of this work is to present the different (NDT) techniques and to explore their limits, taking into account the difficulties presented at the level of the hot part of a turbojet, in order to propose one or more effective means, non subjective and less expensive for the detection and the control of cracks in the hot section of a turbojet. To achieve our goal, we followed the following steps: - Acquire technical, scientific and practical basis of magnetic fields, electrical and electromagnetic, related to industrial applications primarily to electromagnetic NDT techniques. - Apply a scientific approach integrating fundamental knowledge of synthetic and pragmatic manner so as to control the implementation of NDT techniques to establish a synthesis in order to comparing between the use of different methods. - To review recent developments concerning the standard techniques and their foreseeable development: eddy current, ultrasonic guided waves ..., and the possibility of the implication of new techniques.

Abstract: We analyzed the hydrodynamics of the flow into an axis-symmetrical combustion chamber with a central bluff body. Using an axis-symmetrical turbulent flow model we determined the extent of the recirculation region behind the bluff body as well as the location and intensity of maximum kinetic energy as a function of the cone angle of the chamber wall. We showed that by shortening the convergent conical section of the chamber we obtain a compact recirculation with higher turbulence intensity, with positive influence on gas mixing. We used the software FLUENT 6.3 for the numerical simulation of the gas flow inside the combustion chamber. The simplified geometry of the two types of combustion chambers was built using the pre-processor GAMBIT 2.4. Two structured meshes were obtained for the domains of numerical analysis with approximately 170,000 cells each. For modelling the turbulence of the flow we used three different turbulence models which were implemented in FLUENT 6.3.