| In order to avoid quality punishment with carrying additional coolant, hydrocarbon fuel has been applied in regenerative cooling technology as a coolant. In the cooling process, under the influence of dramatic changes of fuel properties within large temperature range at supercritical pressure and endothermic cracking at high temperatures, heat convective of fuel is effectd by coupling between crackin and flow field. A great difficulty of the study to heat convection at supercritical pressure is caused by this complexity coulpling process. Base on the one-dimensional model and multidimensional model, specific to the influence of coupling between crackin and flow field to the fuel heat sink distribution in channel and the influence of local flow field under special cooling structure to heat convective in channel, this thesis has conducted the following investigations:Base on commerce cmpute platform, Engine, GDE-1, is used as the research model, and three dimensional numerical simulation of local special cooling structure has conducted in regionⅠ. The local special cooling structure has been optimized from the view of decreasing flow dead zone、reducing nonuniform of outlet flow distribution of fuel among the channels、reasonable distribution of fuel heat sink. Then, under the influence on changes of fuel physical property, contrastive analysis of flow distribution around local special cooling structure and flow rate distribution characteristics in the downstream channels have been conducted in subcritical temperature、pseudo-critcal temperature and supercritical temperature regions. Therefore, the reasonable location of blockage structure has been proposed.Base on the energy method of heat balance in channel, one dimensional model of coupling between cracking and flow field has been established with considering physical property changes of real gas, and the reliability of model has been validated base on cracking and heat transfer experimental system of hydrocarbon fuel. In order to quantify the coupling between flow and cracking, the Damkohler number, which reflects degree of dependence, has been introduced. The coupling between flow and cracking in flow field along flow direction Base on Da numbel distribution obtained by one dimensional model, coupling between flow and cracking in the flow field along flow direction has been divided quantifiably. Moreover, the distribution of temperature、 flow and cracking have been analysed. At last, a control method of chemical heat sink has been proposed by contrastive analysis of Da numbel and heat sink ratio in different Da numbel regions. Meanwhile, the validity of control method has been demonstrated by change characteristic of Da numbel and chemical heat sink distribution.Aim at coupling flow field between flow and cracking, low velocity reacting flow two-dimensional model at supercritical based on unstructured grid has been established with preconditioned governing equations and time stepping method. The TNT k-ω turbulence model is used, and physical property method is considered into two-dimensional model. Convective term is discreted by reconstitution of physical quantity on section based on Venkatakrishnan second order limiter and preconditioned AUSM+. Discrete equations have been solved coupling with LU-SGS implicit method based on reordering of unstructured grid. Finally, the applicability and reliability of preconditioned coupling time stepping method in low velocity calculations has been verified.Reliability of hydrocarbon fuel coupling between flow and cracking two-dimensional model two-dimensional model has been demonstrated. Base on results of two-dimensional model, boundary layer structure in chemical reaction flow field has been analyzed.Coupling distribution between flow and cracking has been divided into different region base on Da numbel distribution along radial direction, and distribution characteristics of chemical heat sink has been analyzed, therefore, control method of chemical heat sink has been promoted to tow-dimensional flow field.Aim at diffusion of heat flux and convective mass transfer in chemical reaction flow field in radial direction, analysis on heat and mass transfer mechanism has been conducted to flow field in channel. Influence of diffusion of heat flux and convective mass transfer in radial direction to coupling between flow and cracking has been discussed base on the process characteristics time, therefore multi-dimensional flow field structure of cracking flow has been analyzed deeply. Furthermore, flow structure、Da numbel and chemical heat sink distribution under the influence of pressure、flow rate and wall heat flux has been discussed further. |
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