Design, rational optimization, numerical simulation (CFD-analysis) and estimation of the operation efficiency of the heavy vehicle aerodynamic drag reduction device
Area of expertise:
|Keywords||Cargo transportation, drive truck, trailer, external aerodynamic, airflow, streaming, vortex generators, designing, rational optimization, CFD-analysis, aerodynamic drag reduction, fuel saving, finite volume method , DHP*C -Distributive High Productivity Computing|
|Programs in use||ANSYS/CFX|
Computational Mechanics Laboratory (CompMechLab) in 2007 executed multivariate analysis of the 3D airflow for drive truck and trailer (Mercedes Actros) with the purpose of the operation efficiency research for special devices (vortex generators) aimed for aerodynamic drag reduction.
During this project implementation a geometrical model of the drive truck and trailer with vortex generators mounted over the side surface of extender has been created.
Figure 1. 3D geometrical model of the drive truck and trailer with mounted vortex generators
The vortex generator represents an element with intricate shape. To design such device about 10 different construction parameters are used, numerical values of which are specified during of the rational optimization based on multivariate CFD analysis.
Vortex generators are mounted over the surface of side extender or fairing by means of gluing or press forming.
Figure2. Geometrical model and operation principle of vortex generator
The main objective of such device application is generation of vortexes directed towards trailer creating the "barrier" for wind penetration into "gap" between drive truck and trailer during vehicle streaming.
To perform CFD analysis ANSYS ICEM CFD Environment was used to develop the finite-element model of the computational area containing drive truck and trailer.
CFD model consists of about 26 million cells. The SST turbulence model was utilized during numerical simulation. Numerical simulation was carried out with use of the multiple-processor version of ANSYS/CFX.
All computations have been performed in the frameworks of CompMechLab CAD/FEA/CFD/CAE–DHP*C environment, based on problem-oriented, special-generated and arbitrary-scaled computational clusters, created with use of distributed heterogeneous computational and telecommunication resources.
Figure 3. Fragments of CFD-model over the external surfaces of vehicle (~ 26 million of cells)
In the frameworks of executed project the following computations (except rational optimization of vortex generator shape) have been performed:
1. Numerical simulation of the head airflow for drive truck and trailer and analysis of the mounted vortex generators influence on general aerodynamic resistance.
Figure 4. Streamlines at head airflow
2. Numerical simulation of the airflow for drive truck and trailer with cross-wind consideration and analysis of the mounted vortex generators influence on general aerodynamic resistance.
Figure 5. Streamlines at airflow with cross-wind
Executed computations have shown that usage of designed vortex generators is effective both for head airflow and airflow with cross-wind consideration of the drive truck with trailer.
It is necessary to notice that in case with cross-wind the aerodynamic drag reduction may be run up to 10%.
The performed experimental tests have confirmed CFD-results obtained by CompMechLab.