Quantification of Friction-induced Heating in tapered Diesel orifices English Free Members only

  • Category Technical paper
  • Related event International Congress : SIA Powertrain - Rouen 2014 - 21 & 22 May 2014
  • Edition SIA
  • Date 05/21/2014
  • Author G. Strotos, P. Koukouvinis, A. Theodorakakos, M. Gavaises - City University London
  • Language English
  • Type PDF file (894.07 Ko)
    (Downloadable immediately on receipt of online payment)
  • Number of pages 6
  • Code R-2014-02-37
  • Fee Free

Accurate prediction of the liquid fuel temperature field inside micro-flow channels operating under extreme liquid pressurization may have significant impact on the determination of the flow distribution, fuel exit temperature and nozzle discharge coefficient. In this paper, the Navier- Stokes equations are numerically solved to predict the turbulent flow inside a Diesel injector nozzle for fixed position of the needle valve controlling its opening and closing function. The temperature field is obtained by solving the energy equation which includes the effect of viscous heating; adiabatic walls have been assumed in an effort to simplify the process and reveal how fluid flow rather than external heating affects the liquid temperature. The effect of including variable fuel properties as a function of local pressure and temperature relative to predictions obtained with fixed values is quantified. It is shown that the assumption of constant properties leads to significant heating over-prediction. Furthermore, injectors with high volumetric efficiency (Cd values close to 1) fuel sub-cooling relative to the inlet conditions may
occur during depressurization. Moreover, a comparison between single-phase and cavitating conditions is made. Predictions for the fuel heating caused during the discharge of the pressurized Diesel fuel through the micro-hole orifices is made against 0-D thermodynamic predictions showing good match. The 3-D results indicate a significant variation of the predicted temperature distribution on the wall surfaces, while possible regions of heterogeneous boiling are also indicated.

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