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Proceedings ArticleDOI

Influence of a High-Swirling Helical Port with Axisymmetric Piston Bowls on In-Cylinder Flow in a Small Diesel Engine

05 Apr 2016-

AboutThe article was published on 2016-04-05. It has received 1 citation(s) till now. The article focuses on the topic(s): Piston & Diesel engine. more

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Journal ArticleDOI
Abstract: New induction manifold designs have been developed in this work to enhance the turbulence intensity and improve the mixing quality inside diesel engine cylinders. These new designs employ a spiral-helical shape with three different helical diameters (1D, 2D, 3D; where D is the inner diameter of the manifold) and three port outlet angles: 0 deg, 30 deg, and 60 deg. The new manifolds have been manufactured using three-dimensional printing technique. Computational fluid dynamics simulations have been conducted to estimate the turbulent kinetic energy (TKE) and the induction swirl generated by these new designs. The combustion characteristics that include the maximum pressure raise rate (dP/dθ) and the peak pressure inside the cylinder have been measured for a direct injection (DI) diesel engine utilizing these new manifold designs. In addition, engine performance and emissions have also been evaluated and compared with those of the normal manifold of the engine. It was found that the new manifolds with 1D helical diameter produce a high TKE and a reasonably strong induction swirl, while the ones with 2D and 3D generate lower TKEs and higher induction swirls than those of 1D. Therefore, dP/dθ and peak pressure were the highest with manifolds 1D, in particular manifold m (D, 30). Moreover, this manifold has provided the lowest fuel consumption with the engine load by about 28% reduction in comparison with the normal manifold. For engine emissions, m (D, 30) manifold has generated the lowest CO, SO2, and smoke emissions compared with the normal and other new manifolds as well, while the NO emission was the highest with this manifold.

7 citations

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01 Jan 1988
Abstract: 1 Engine Types and Their Operations 2 Engine Design and Operating Parameters 3 Thermochemistry of Fuel-Air Mixtures 4 Properties of Working Fluids 5 Ideal Models of Engine Cycles 6 Gas Exchange Processes 7 SI Engine Fuel Metering and Manifold Phenomena 8 Charge Motion within the Cylinder 9 Combustion in Ignition Engines 10 Combustion in Compression Ignition Engines 11 Pollutant Formation and Control 12 Engine Heat Transfer 13 Engine Friction and Lubrication 14 Modeling Real Engine Flow and Combustion Processes 15 Engine Operating Characteristics Appendixes

14,157 citations

01 Jun 1995
TL;DR: This chapter discusses the development of the Finite Volume Method for Diffusion Problems, a method for solving pressure-Velocity Coupling in Steady Flows problems, and its applications.
Abstract: *Introduction. *Conservation Laws of Fluid Motion and Boundary Conditions. *Turbulence and its Modelling. *The Finite Volume Method for Diffusion Problems. *The Finite Volume Method for Convection-Diffusion Problems. *Solution Algorithms for Pressure-Velocity Coupling in Steady Flows. *Solution of Discretised Equations. *The Finite Volume Method for Unsteady Flows. *Implementation of Boundary Conditions. *Advanced topics and applications. Appendices. References. Index.

7,132 citations

Journal ArticleDOI
Abstract: A non-iterative method for handling the coupling of the implicitly discretised time-dependent fluid flow equations is described. The method is based on the use of pressure and velocity as dependent variables and is hence applicable to both the compressible and incompressible versions of the transport equations. The main feature of the technique is the splitting of the solution process into a series of steps whereby operations on pressure are decoupled from those on velocity at each step, with the split sets of equations being amenable to solution by standard techniques. At each time-step, the procedure yields solutions which approximate the exact solution of the difference equations. The accuracy of this splitting procedure is assessed for a linearised form of the discretised equations, and the analysis indicates that the solution yielded by it differs from the exact solution of the difference equations by terms proportional to the powers of the time-step size. By virtue of this, it is possible to dispense with iteration, thus resulting in an efficient implicit scheme while retaining simplicity of implementation relative to contemporary block simultaneous methods. This is verified in a companion paper which presents results of computations carried out using the method.

3,486 citations

Journal ArticleDOI
Abstract: Turbulence models are developed by supplementing the renormalization group (RNG) approach of Yakhot and Orszag [J. Sci. Comput. 1, 3 (1986)] with scale expansions for the Reynolds stress and production of dissipation terms. The additional expansion parameter (η≡SK/■) is the ratio of the turbulent to mean strain time scale. While low‐order expansions appear to provide an adequate description for the Reynolds stress, no finite truncation of the expansion for the production of dissipation term in powers of η suffices−terms of all orders must be retained. Based on these ideas, a new two‐equation model and Reynolds stress transport model are developed for turbulent shear flows. The models are tested for homogeneous shear flow and flow over a backward facing step. Comparisons between the model predictions and experimental data are excellent.

2,056 citations

Proceedings ArticleDOI
Abstract: Recently developed computer models are being applied to calculate complex interactions between sprays and gas motions. The three-dimensional KIVA code was modified to address drop breakup and was used to study fuel sprays. The results show that drop breakup influences spray penetration, vaporization and mixing in high pressure sprays. The spray drop size is the outcome of a competition between drop breakup and drop coalescence phenomena, and the atomization details at the injector are lost during these size rearrangements. Drop breakup dominates in hollow-cone sprays because coalescence is minimized by the expanding spray geometry. The results imply that it may be possible to use a simple injector and still control spray drop size and vaporization if the flow details are modified so as to enhance drop breakup and coalescence.

402 citations