Assessment of compressibility effects on internal nozzle flow in diesel injectors at very high injection pressures

Abstract

Diesel fuel injection systems are being used at higher injection pressure conditions over time because of more stringent emissions requirements. Thus, the importance to properly take into account the fluid compressibility on injection CFD simulations is also increasing. In this paper, an investigation of the compressibility effects in nozzle flow simulations has been carried out for injection pressures up to 250 MPa. To do so, the fluid properties (including density, viscosity and speed of sound) have been measured in a wide range of boundary conditions. These measurements have allowed to obtain correlations for the fluid properties as a function of pressure and temperature. Then, these equations have been incorporated to a CFD solver to take into account the variation of the fluid properties with the pressure changes along the computational domain. The results from

Model Issues Regarding Modification of Fuel Injector Components to Improve the Injection Parameters of a Modern Compression Ignition Engine Powered by Biofuel

“…Flow simulation allows us to simulate heat transfer between solids and fluids. Heat transfer conversion has been described by energy conservation Equations (11) and (12). Heat flux is defined by Equation (13).…”

“…This results in increased pressure in the combustion chamber and a higher emission of nitrogen oxides. Density, viscosity and sound velocity value have an impact on the compressibility factor of the fuel during flow through the fuel atomizer holes, but they do not affect the Reynolds number Salvador et al [12]. The fuel injection CFD simulation was carried out in two phases: Incompressible flow at constant liquid properties and compressible flow at liquid properties, calculated locally as a function of flow pressure conditions.…”

Sensitivity analysis of the dynamic response of an electronic fuel injector regarding fuel properties and operating conditions

“…[22] and Payri et al [23]. In addition, fuel properties change in vast ranges of different pressures and temperatures, as were revealed by Salvador et al [24] and Desantes et al [25].…”

“…The boundaries of the three fuel properties derive from the Figure 2 of the reference [24]. In that figure, the fuel properties of a stand winter diesel fuel are shown for a range of 0.1-300…”

An investigation of the validity of a homogeneous equilibrium model for different diesel injector nozzles and flow conditions

“…in which Ψ l is the compressibility of the liquid. Despite this, there are models describing the compressibility of the mixture in a more physical way, as well as studies focusing on compressibility effect [22] but a linear formula is chosen in this work due to the stability and convergence advantages. As for compressibility, it is possible to obtain the viscosity of the mixture through a linear equation:…”