The Application And Research Of The Unstructured Grid FVM In The Turbulent Reaction Flows Simulation With Complex Geometries

The unstructured FVM is fit for the complex flow field calculation, and the SIMPLE series algorithms are fit for the low march number, or incompressible flow field calculation, Euler-Largrange method is fit for the sparse spray flow field calculation. Based on these above, the preprocessing and postprocessing with CGNS system, the implementation and modification of SIMPLE series algorithms, the models of the species source term, the ineraction between the particle phase and the gas phase, and so on are carried out. The details are below:Two hash methods forming the face structure from the node structure of the unstructured CGNS mesh are the bases to operate the unstructured mesh in this paper: the integer number hash method for the inner faces formation and the real number hash method for the two-side wall boundary faces formation. Because the node data is stored by the unstructured CGNS mesh, for example, the node coordinates, the node index list of every grid. The face intigral is very usual in Finite Volume method, so the shifting from node to face is needed. The same node index list in the interface of two neighbour cells is employed to formate the inner face, and the distance between the centers of two faces in a two-side wall boundary is approximate to zero, or else less than a specified real number for example the square root of the area of the faces, and this is the key point to formate faces in this kind of boundarys. The two method make the faces formation is very quick, and the computer memory consumed is less than the FVM solver, so the CGNS preprocessing is not the bottle neck of the whole computation.In the formation of the pressure correction equation, the influence of the temperature correction to the density correction is considered, the relationship between the temperature correction and the pressure correction is based on the static enthalpy equation. This method enhanced the primary diagonal coefficient of the pressure correction equation. To the compressible flow calculation, some hybrid methods of low order and high order blending interpolation are employed, such as the hybrid method to get the density of the face mass flux, the hybrid method for the pressure term in the momentum equations, the transient term calculation. These methods compromise btween the resolution and stability.The turbulent combustion species models such as EBU, Eddy Dissipation, Arrinius/EBU/ED, presumed PDF are employed to simulate the spray combustion. In this paper, the momentunm interaction between particle phase and gas phase is modeled by splitting the drag force coefficients, shifting to the Euler system from the Largrange system, adding these coeffients to the diagonal coefficients of the gas phase momentum equation linear algebraic matrix, and the added coefficients are positive, so the diagonal coefficients are enhanced and the calculation stability is enhanced. With the time marching method calculating the steady fields, the explicit and implicit methods of the coupling particulate flow are researched in this paper. With this method a larger time step can be used to reduce the calculation of the time marching progress.In the in-house CFD software developing of our team, some tasks are finished by the writer of this paper. Some calculation cases compared to the commercial software prove the correctness of the methods in this paper.