Transient Cavitation and Friction-Induced Heating Effects of Diesel Fuel during the Needle Valve Early Opening Stages for Discharge Pressures up to 450 MPa

Abstract

An investigation of the fuel heating, vapor formation, and cavitation erosion location patterns inside a five-hole common rail diesel fuel injector, occurring during the early opening period of the needle valve (from 2 μm to 80 μm), discharging at pressures of up to 450 MPa, is presented. Numerical simulations were performed using the explicit density-based solver of the compressible Navier–Stokes (NS) and energy conservation equations. The flow solver was combined with tabulated property data for a four-component diesel fuel surrogate, derived from the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state (EoS), which allowed for a significant amount of the fuel’s physical and transport properties to be quantified. The Wall Adapting Local Eddy viscosity (WALE) Large Eddy Simulation (LES) model was used to resolve sub-grid scale turbulence, while a cell-based mesh deformation arbitrary Lagrangian–Eulerian (ALE) formulation was used for modelling the injector’s needle valve movement. Friction-induced heating was found to increase significantly when decreasing the pressure. At the same time, the Joule–Thomson cooling effect was calculated for up to 25 degrees K for the local fuel temperature drop relative to the fuel’s feed temperature. The extreme injection pressures induced fuel jet velocities in the order of 1100 m/s, affecting the formation of coherent vortical flow structures into the nozzle’s sac volume.

Optimization of Design and Technology of Injector Nozzles in Terms of Minimizing Energy Losses on Friction in Compression Ignition Engines

“…The nozzle needle design concept which was considered in the research project was focused on maximizing the contact area between the needle and its cartridge to reduce needle wear [27]. The injector feeding part was realized using two series of holes.…”

Prediction of shock heating during ultrasound-induced bubble collapse using real-fluid equations of state

“…Popinet et al [43] explored the viscosity's impact on bubble collapse near solid surfaces where reduction of the jet impact velocity at higher viscosity was observed. There are also some relevant studies for cavitation modelling using mass transfer rates [44] , [45] , [46] , [47] , [48] , cavitation modelling using air-vapor–liquid and barotropic EoS [49] , [50] , [51] , [52] , [53] , and heating effects and real-fluid thermodynamic closure in cavitating flows [54] , [55] , [56] .…”

Assessment of Injector-Flow Characteristics of Additised and Renewable Diesel Blends Through High-Speed Imaging

“…The formation and dynamic evolution of vaporous structures within the injector affect its discharge coefficient, the dynamics and composition of the expelled spray [11][12][13] and pose a threat to the injector rigidity [14][15][16]. Transparent tips have been usually made from acrylic or even quartz which, are capable of withstanding extreme pressures up to 2000 bar [17,18].…”