Investigation of Flow Fields Emanating from Two Parallel Inlet Valves Using LES, PIV, and POD

Energies, vol. 16, pp. 6917

Abstract

Understanding cycle-to-cycle variations (CCV) is of practical importance for the combustion of fossil and renewable fuels, as increasingly stringent emission regulations require reductions in the negative effects of such variations. The subject of this study is the flow around inlet valves, since oscillations of such inlet flows affect the flow structure in the cylinder and are thus one of the causes of CCV. To this end, a parametric analysis of the influences of the mass flow rate and valve lift of two parallel engine intake valves on the flow structures is performed. This follows on from an earlier similar study where the flow around a single intake valve was investigated. To analyse the flow behaviour and, in particular, the interactions of the flow leaving these two valves, an optical test rig for 2D particle image velocimetry (PIV) and a large eddy simulation (LES) are used. Proper orthogonal decomposition (POD), together with a quadruple decomposition and the Reynolds stress transport equations, are used to study the turbulence phenomena. The PIV and LES results are in good agreement with each other. The detailed LES analysis of the flow structures shows that, for small valve lifts, the flow separates along the whole perimeter of the intake valve, and for larger valve lifts, the flow escapes only to one side. This is, for combustion engines with the tumble concept, the stage at which the tumble movement develops. Moreover, the flow structures are strongly influenced by the valve lift, while they are unaffected by the variation in the mass flow. The turbulent kinetic energy in the flow field increases quadratically with a decreasing valve lift and increasing mass flow. The large, high-energetic flow structures are particularly dominant near the jet, and the small, low-energetic structures are homogeneously distributed within the flow field. The specific Reynolds stress transport equation shows the limitations of two-dimensionality and large timesteps in the PIV results and the limitations of the LES model.

Authors 9

1. Jana Hoffmann corresponding

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland

2. Walter Vera-Tudela

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland

3. Niklas Mirsch Aachen Thermodynamics of Mobile Energy Conversion Systems

   RWTH Aachen University

   Affiliation as printed

   Thermodynamics of Mobile Energy Conversion Systems (TME), RWTH Aachen University, Forckenbeckstrasse 4, 52074 Aachen, Germany

4. Dario Wüthrich

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland

5. Bruno Schneider

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland

6. Marco Günther Aachen Thermodynamics of Mobile Energy Conversion Systems

   RWTH Aachen University

   Affiliation as printed

   Thermodynamics of Mobile Energy Conversion Systems (TME), RWTH Aachen University, Forckenbeckstrasse 4, 52074 Aachen, Germany

7. Stefan Pischinger Aachen Thermodynamics of Mobile Energy Conversion Systems

   RWTH Aachen University

   Affiliation as printed

   Thermodynamics of Mobile Energy Conversion Systems (TME), RWTH Aachen University, Forckenbeckstrasse 4, 52074 Aachen, Germany

8. Daniel A. Weiss

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland

9. Kai Herrmann

   FHNW University of Applied Sciences and Arts Northwestern Switzerland

   Affiliation as printed

   Institute of Thermal and Fluid Engineering (ITFE), University of Applied Sciences and Arts Northwestern Switzerland, Klosterzelgstrasse 2, 5210 Windisch, Switzerland