Multi-phase thermal cavitation flow in rough conforming and partially conforming conjunctions

The main aim of this research was to investigate the mechanism of cavitation in conforming and partially conforming tribological conjunctions. The effect of cavitation on load carrying capacity and frictional performance of is also investigated. This is important with regards to fuel efficiency in internal combustion (IC) engines. Friction accounts for 15–20% of IC engine losses. The piston–cylinder system contributes to 40–50% of these, with the compression ring(s) being responsible for most of this. This is because the primary function of the ring is to seal the combustion chamber, thus small emerging gaps lead to increased friction. In fact, compression ring(s) expend 3–5% of engine input fuel energy. The share of frictional losses of engine bearings is approximately 20–25%. Traditionally, prediction of performance of tribological conjunctions has been studied using Reynolds equation. When the effect of cavitation is considered, various cavitation algorithms with associated boundary conditions for lubricant rupture and reformation are proposed. These include Elrod, and Elrod and Coyne algorithms, as well as boundary conditions such as Swift-Stieber, JFO and Prandtl-Hopkins. There are a number of assumptions embodied in these approaches, as well as the use of Reynolds equation itself. These approaches do not uphold the continuity of mass and momentum in multi-phase flow, in cavitation beyond the lubricant film rupture. A detailed methodology for multi-phase flow, comprising simultaneous solution of Navier-Stokes, energy and lubricant rheological state equations is developed. [Continues.

VIM Solution for Mixed Convection over Horizontal Moving Porous Flat Plate

The non-viscous, laminar mixed convection boundary-layer flow over a horizontal moving porous flat plate, with chemical reaction, is considered. The governing equations are expressed in non-dimensional form and the series solutions of coupled system of equations are constructed for velocity, temperature and concentration functions using variational iteration method. The investigated parameters are: buoyancy parameter, chemical reaction parameter, order of chemical reaction, Prandtl number and Schmidt number

A series solution for three-dimensional Navier-Stokes equations of flow near an infinite rotating disk

In this paper, homotopy analysis method (HAM) and Padé approximant will be considered for finding analytical solution of three-dimensional viscous flow near an infinite rotating disk which is a well-known classical problem in fluid mechanics. The solution is compared to the numerical (fourth-order Runge-Kutta) solution and the convergence of the obtained series solution is carefully analyzed. The results illustrate that HAM-Padé is an appropriate method in solving the systems of nonlinear equations

Explicit Analytic Solution for an Axisymmetric Stagnation Flow and Heat Transfer on a Moving Plate

Abstract In this article, we use an efficient analytical method called homotopy analysis method (HAM) to derive an approximate solution of an axisymmetric stagnation flow on a moving solid boundary. Actually, we solved the Navier-Stocks and energy equations by the HAM. Unlike the perturbation method, the HAM does not require the addition of a small physically parameter to the differential equation. It is applicable to strongly and weakly nonlinear problems. Moreover, the HAM involves an auxiliary parameter, h which renders the convergence parameter of series solutions Controllable, and increases the convergence, and increases the convergence significantly. This article depicts that the HAM is an efficient and powerful method for solving nonlinear differential equations

Big end bearing losses with thermal cavitation flow under cylinder deactivation

The paper presents a mixed thermo-hydrodynamic analysis of elliptic bore bearings using combined solution of Navier–Stokes, continuity and energy equations for multi-phase flow conditions. A vapour transport equation is also included to ensure continuity of flow in the cavitation region for the multiple phases as well as Rayleigh–Plesset to take into account the growth and collapse of cavitation bubbles. This approach removes the need to impose artificial outlet boundary conditions in the form of various cavitation algorithms which are often employed to deal with lubricant film rupture and reformation. The predictions show closer conformance to experimental measurements than have hitherto been reported in the literature. The validated model is then used for the prediction of frictional power losses in big end bearings of modern engines under realistic urban driving conditions. In particular, the effect of cylinder deactivation (CDA) upon engine bearing efficiency is studied. It is shown that big-end bearings losses contribute to an increase in the brake specific fuel consumption with application of CDA contrary to the gains made in fuel pumping losses to the cylinders. The study concludes that implications arising from application of new technologies such as CDA should also include their effect on tribological performance

CFD modeling of cavitation flow in journal bearing lubrication

CFD modeling of cavitation flow in journal bearing lubricatio

A CFD study comparing surface texture features on stationary and entraining surfaces

A CFD study comparing surface texture features on stationary and entraining surface

CFD modelling of cavitation phenomenon in piston ring / cylinder liner conjunction

CFD modelling of cavitation phenomenon in piston ring / cylinder liner conjunctio