摘要:

AbstractAn analysis of the erosion behaviour of a turbocharger radial turbine is presented. The solution domain includes both sides of the radial turbine scroll with double intake and the rotor channel. In the analysis a dilute gas‐particle flow assumption is employed. The gas turbulence is defined by thek‐ε model. In solving the gas phase equation, the computer code Harwell‐FLOW3D is employed, which is based on a finite volume formulation using non‐orthogonal body‐fitted structured gridding and a pressure correction method. The particle phase is described by a Lagrangian approach, while particle paths are computed deterministically, neglecting the turbulent dispersion. For the computation of particle trajectories the code PTRACK is employed, which has been developed at ABB. Computations are carried out for several particle size classes. The results show that particles are thrown back into the scroll by the rotor at high rates. This seems to be the main source of erosion effects in the scroll. It has been observed that particles are unequally distributed between the scroll sides on their re‐entry, resulting in greater erosion on one of the scroll sides. The maximum erosion along the scroll is found to be likely to occur near th

ISSN:0271-2091    

DOI:10.1002/fld.1650160402

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA numerical algorithm is used to study the ‘fan‐spreading’ mechanism of axial particle turbulence acquisition and the effects on it of the inlet particle diameter distribution, downstream of a particle‐laden, turbulent, round jet. The algorithm is based on the particle‐source‐in‐cell numerical technique for two‐phase flows. Eulerian equations are used for the description of the gas‐phase dynamics, whilst the solid particles are treated within the Lagrangian framework. The turbulent particle dispersion is simulated with the aid of the stochastic separated flow model. It was found that the ‘fan‐spreading’ turbulence is very much affected by the mean and standard deviation of the particle size distribution; in particular, it was found that the ‘fan‐spreading’ mechanism becomes weaker when the standard deviation of the particle diameter distribution is higher and the mean particle diameter smaller. An analytical expression describing the axial particle turbulence due to ‘fan‐spreading’ is proposed and tested, along with a similarity profile val

ISSN:0271-2091    

DOI:10.1002/fld.1650160403

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA finite volume numerical method for the prediction of fluid flow and heat transfer in simple geometries was parallelized using a domain decomposition approach. The method is implicit, uses a colocated arrangement of variables and is based on the SIMPLE algorithm for pressure‐velocity coupling. Discretization is based on second‐order central difference approximations. The algebraic equation systems are solved by the ILU method of Stone.1To accelerate the convergence, a multigrid technique was used. The efficiency was examined on three different parallel computers for laminar flow in a pipe with an orifice and natural convection in a closed cavity. It is shown that the total efficiency is made up of three major factors:numerical efficiency, parallel efficiencyandload‐balancing efficiency. The first two factors were thoroughly investigated, and a model for predicting the parallel efficiency on various computers is presented. Test calculations indicate reasonable total efficiency and favourable dependence on grid size and the number of proce

ISSN:0271-2091    

DOI:10.1002/fld.1650160404

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe specified‐time‐interval (STI) scheme has been used commonly in applying the method of characteristics (MOC) to unsteady open‐channel flow problems. However, with the use of STI scheme, the numerical error for the simulation results can always be induced due to the interpolation used to approximate the characteristics trajectory. Hence, in order to remedy the numerical errors caused by the interpolation, one needs to seek some kind of interpolation technique with higher‐order accuracy. Instead of the linear interpolation technique, which has been used very commonly and can induce serious numerical diffusion, the Holly‐‐Preissmann two‐point, method, which is a cubic interpolation technique with fourth‐order of accuracy, is proposed here to integrate with the method of characteristics for the computation of one‐dimensional unsteady flow in open channel. The concept of reachback and reachout in space and time directions for the characteristics is also introduced to assure the model stability. The computed results from this new model are compared with those computed by using the Preissmann four‐point scheme and the multimode method of characteristics with l

ISSN:0271-2091    

DOI:10.1002/fld.1650160405

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650160406

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650160407

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650160401

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY