Active control of the charge motion by fluidic vortex generators

• Applicants: Professor Dr.-Ing. Peter Eilts; Dr.-Ing. Peter Scholz
• Subject Area: Hydraulic and Turbo Engines and Piston Engines ; Fluid Mechanics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 511725940

Modern internal combustion engines utilize a designed motion of the cylinder charge to support mixture formation and/or combustion. For the generation of charge motion appropriately shaped intake ports are used. Generally an increase in charge motion causes a reduced flow capacity and thus an increased charge exchange work. In this project an alternative method of swirl generation will be investigated. As a basis a port is used which creates little charge motion. This will be increased by tangential pulsed injection of air into the port close to the valve seat. This makes it possible to vary the swirl continuously, different from switching ports on and off as usual. Further the preliminary work shows that the work needed to produce the compressed air is less than the increase of charge exchange work that would result from using a swirl port. The project will be carried out at the Institute of Fluid Mechanics (ISM) and the Institute of Internal Combustion Engines (ivb) at TU Braunschweig. Initially a series of ports will be designed, based on the preliminary work. These will be investigated by ISM with stationary RANS-simulations. The result is a pareto front of swirl vs. flow capacity. From this pareto front three ports with different swirl level will be chosen. They will be investigated experimentally on the flow test bench of ivb, in order to verify the simulation results. Further tests with air injection will be carried out using the ports with low and medium swirl. For unsteady investigations a test bed with a motored engine will be built up. The cylinder head will be designed such, that the inlet ports can be exchanged easily. The flow measurements will be carried out with hot wire anemometers, because with this technique the results are available much faster than with optical methods. This is important because of the large parameter space due to the variabilities of the air injection. The ISM will build up a simulation chain of uRANS- and IDDES-simulations for the unsteady investigations. OpenFOAM will be used as the simulation software. Using these tools a systematic optimisation will be carried out. The target is a parameter constellation, which gives a preferably high increase in swirl with a preferably low work for the production of compressed air. Then a port can be used which produces low swirl without air injection and has thus a high flow capacity. Finally engine simulations will be carried out for evalution. With a jointly adjusted approach involving experimental parameter studies and detailed recalculations with scale resolving simulations the effect of air injection on the development of swirl and the connected sensitivities can be explained and described.

• DFG Programme: Research Grants