Computational Fluid Dynamics(CFD) Analysis and Optimization of Reconstructed Intake System of Cylinder Head Based on Slicing Reverse Method

To find out and improve the flow characteristics inside the intake system of cylinder head,the application of computational fluid dynamics(CFD)in the evaluation and optimization of the reconstructed intake system based on slicing reverse method was proposed.The flow characteristics were found out through CFD,and the velocity vector field,pressure field and turbulent kinetic energy field for different valve lifts were discussed,which were in good agreement with experimental data,and the quality of reconstruction was evaluated.In order to improve its flow characteristic,an optimization plan was proposed.The results show that the flow characteristics after optimization are obviously improved.The results can provide a reference for the design and optimization of the intake system of cylinder head.

Time-accurate CFD conjugate analysis of transient measurements of the heat-transfer coefficient in a channel with pin fins

Heat-transfer coefficients(HTC)on surfaces exposed to convection environments are often measured by transient techniques such as thermochromic liquid crystal(TLC)or infrared thermography.In these techniques,the surface temperature is measured as a function of time,and that measurement is used with the exact solution for unsteady,zero-dimensional(0-D)or one-dimensional(1-D)heat conduction into a solid to calculate the local HTC.When using the 0-D or 1-D exact solutions,the transient techniques assume the HTC and the free-stream or bulk temperature characterizing the convection environment to be constants in addition to assuming the conduction into the solid to be 0-D or 1-D.In this study,computational fluid dynamics(CFD)conjugate analyses were performed to examine the errors that might be invoked by these assumptions for a problem,where the free-stream/bulk temperature and the heat-transfer coefficient vary appreciably along the surface and where conduction into the solid may not be 0-D or 1-D.The problem selected to assess these errors is flow and heat transfer in a channel lined with a staggered array of pin fins.This conjugate study uses three-dimensional(3-D)unsteady Reynolds-averaged Navier-Stokes(RANS)closed by the shear-stress transport(SST)turbulence model for the gas phase(wall functions not used)and the Fourier law for the solid phase.The errors in the transient techniques are assessed by comparing the HTC predicted by the time-accurate conjugate CFD with those predicted by the 0-D and 1-D exact solutions,where the surface temperatures needed by the exact solutions are taken from the time-accurate conjugate CFD solution.Results obtained show that the use of the 1-D exact solution for the semi-infinite wall to give reasonably accurate“transient”HTC(less than 5%〇relative error).Transient techniques that use the 0-D exact solution for the pin fins were found to produce large errors(up to 160%relative error)because the HTC varies appreciably about each pin fin.This study also showed that HTC measured by transient techniques could differ considerably from the HTC obtained under steady-state conditions with isothermal walls.

Design and analysis of annular combustion chamber of a low bypass turbofan engine in a jet trainer aircraft

The design of an annular combustion chamber in a gas turbine engine is thebackbone of this paper.It is specifically designed for a low bypass turbofan engine in a jettrainer aircraft.The combustion chamber is positioned in between the compressor and turbine.lt has to be designed based on the constant pressure,enthalpy addition process.The presentmethodology deals with the computation of the initial design parameters from benchmarking ofreal-time industry standards and arriving at optimized values.It is then studied for feasibilityand finalized.Then the various dimensions of the combustor are calculated based on differentempirical formulas.The air mass flow is then distributed across the zones of the combustor.The cooling requirement is met using the cooling holes.Finally the variations of parameters atdifferent points are calculated.The whole combustion chamber is modeled using Siemens NX8.0,a modeling software and presented.The model is then analyzed using various parametersat various stages and levels to determine the optimized design.The aerodynamic flowcharacteristics is simulated numerically by means of ANSYS 14.5 software suite.The air-fuelmixture,combustion-turbulence,thermal and cooling analysis is carried out.The analysis isperformed at various scenarios and compared.The results are then presented in image outputsand graphs.

Experimental and computational analysis of the coolant distribution considering the viscosity of the cutting fluid during machining with helical deep hole drills

An experimental analysis regarding the distribution of the cutting fluid is very difficult due to the inaccessibility of the contact zone within the bore hole.Therefore,suitable simulation models are necessary to evaluate new tool designs and optimize drilling processes.In this paper the coolant distribution during helical deep hole drilling is analyzed with high-speed microscopy.Micro particles are added to the cutting fluid circuit bya developed high-pressure mixing vessel.After the evaluation of suitable particle size,particle concentration and coolant pressure,a computational fluid dynamics(CFD)simulation is validated with the experimental results.The comparison shows a very good model quality with a marginal difference for the flow velocity of 1.57%between simulation and experiment.The simulation considers the kinematic viscosity of the fluid.The results show that the fluid velocity in the chip flutes is low compared to the fluid velocity at the exit of the coolant channels of the tool and drops even further between theguidechamfers.Theflow velocity and the flow pressure directly at the cutting edge decrease to such an extent that the fluid cannot generate a sufficient cooling or lubrication.With the CFD simulation a deeper understanding of the behavior and interactions of the cutting fluid is achieved.Based on these results further research activities to improve the coolant supply can be carried out with great potential to evaluate new tool geometries and optimize the machining process.