Engineering

Turbocharging

FEV offers a wide spectrum of engineering services to OEMs, suppliers and turbocharger manufacturers in the field of charging combustible engines and fuel cells. Highly complex questions can be answered quickly and fully using our long-term expertise in the fields of method development, simulation and trial. In addition to the measurement and assessment of exhaust turbochargers, the optimization of interaction between combustion engines and charging systems is paramount for FEV.

In summary, FEV offers the following services in the field of charging:

Design and development of turbochargers
Trial approaches for exhaust turbochargers and charging systems
1D and 3D simulation methods for the optimization and analysis of aerodynamics and bearings
Turbocharger acoustics (test and simulation)
Design and production of test benches for turbochargers
Experience in the solution of charging system problems (prototype and series applications)
Software tools

Our Range

Trial Possibilities

In recent years, FEV has permanently expanded its capabilities in the trial of charging systems. Tests of the entire system, as well as of individual components, are possible in the following facilities:

Hot gas test benches for turbochargers
(endurance test, function tests, thermodynamics, Stationary characteristics measurement, expanded characteristics measurement with RAM and CCL, measurements with package, component tests, variability examinations, endurance tests, acoustic and PIV measurements)
Bearing friction test bench for turbocharger
(Bearing friction depending on speed, axial thrust measurements on the hot gas test bench, shaft raceway, blow-by measurement)
Inertia test bench for turbocharger
Engine test bench
(Determination of efficiency level in combination with the engine, acoustic measurement, and endurance tests)
Special installations as needed
(e.g. electric compressor, turbine break measurement)

On the hot gas test bench, the characteristics of all charging systems from the passenger vehicle and commercial vehicle fields can be measured separately and including the package up to a maximum mass flow of 1 kg/s. A characteristics expansion is made possible by a closed-loop operation. For the examination of multi-flow turbochargers, it is also possible to measure the individual flows separately and display partial admission flow conditions (incl. cross-talk behavior). Targeted examinations with waste gate or VTG turbines and for individual components can also be carried out during endurance tests. Research examinations with optical and acoustic measurement procedures are part of the trial portfolio.

Benchmarking Process

FEV has developed a unique benchmarking process for the entire drive train. The largest database for automobile turbochargers was generated on this basis. It includes data from 14 different turbocharger manufacturers from the production, after market introduction, as well as data about prototypes (status 7/2017). In total, more than 250 turbochargers were measured under the same conditions using the same test setup to guarantee the direct comparability of the measurements. FEV is a proven service provider for the implementation of benchmarking programs of leading turbocharger manufacturers and OEMs. Diverse design and performance aspects can be evaluated by programmed routines within the FEV turbocharger benchmark database. The customer can configure an evaluation package from 30 possible comparisons beforehand. In addition, experts from FEV give evaluative feedback regarding the turbocharger under examination in order to support the development process and to optimize the product.

The following analyses are available as examples. The following three examples show an excerpt of the benchmarking program.

Turbine Efficiency Level and Volumetric Flow Capacity vs. Turbine Diameter

Turbinen-Wirkungsgrad und Durchflussrate vs. Laufradgröße

Compressor Pressure Ratio vs. Mass Flow Rate and Maximum Compressor Efficiency vs. Compressor Map Width

Verdichter-Druckverhältnis vs. Massenstrom und Max. Verdichter-Wirkungsgrad vs. Kennfeld-Breite

Motor and turbocharger interaction

Turbocharger Methods and Tools

FEV offers an extensive portfolio of software tools to enable the realistic modeling of turbochargers and to support the commercial engine design process, i.e. Using GT-POWER™. Aerodynamic phenomena, bearing friction and aspects of heat transfer are taken into account. Through the optimal combination of in-house soft development and validation at test benches, FEV models for load change programs fulfill the high demands of current development trends.

The software package FEV TCtools serves to prepare measurement and simulation data in the run-up to the charge change simulation. Aerodynamic effects and heat transport can be separated in an automated process of efficiency level calculation. A scaling of turbine and compressor (casing and rotor) is also possible to implement the targeted parameter studies. The application portfolio is rounded off by a physically based extrapolation tool, which expands existing data fields in such a way that the entire operating range can be fully simulated in charge exchange programs.

Turbocharger Simulations

3D CFD

In addition to various possibilities in the field of testing, FEV also has advanced expertise in the numeric examinations of turbochargers. The process that begins with the transfer of CAD data is automated to the greatest extent possible, whereby the complicated and time-consuming new connection can be avoided even for changes in the geometry by switching the waste gate position on the turbocharger, for example. In addition to stationary examinations with the frozen rotor approach, fully transient CFD examinations are located in the FEV portfolio. The simulation under various conditions and the post-processing of the results are also part of the automated process.

In addition to adiabatic characteristic simulations, FEV has a lot of experience in the simulation of entire turbocharger models, including heat transfers between fluid and solid body structure (Conjugate Heat Transfer). Evaluation levels can be placed at any point within the 3D CFD models in order to fully evaluate the aerodynamic performance independently of complex measuring equipment at the test bench. Numeric examinations are also offered in the area of the catalyst inflow and the exhaust manifold as connecting engine components to the turbocharger. The simulation results are incorporated as a framework condition or as a comparison in the optimization of individual components or serve as an assessment of operational behavior in the preliminary selection of turbochargers.

Bearings and multi-body simulation

The radial bearings of the rotor of an exhaust turbocharger (ETC) are usually listed as hydrodynamic fully floating bushing bearings, individually as roller bearings. Axial guidance is usually handled by a double-sided, hydrodynamic axial segment bearing. The complete rotor dynamics of the ETC and the bearing behavior are analyzed using elastic multibody simulation (MBS) and the coupled thermo-elasto-hydrodynamic (TEHD) calculations with the help of the commercial MBS software FEV Virtual Engine ©.

In addition to synchronous and subsynchronous vibrations, the hydrodynamic lubricant film pressures and bearing friction can also be determined in this way in the early ETC development phase and optimized early on in the ETC.

Typical computational results here are

Bearing reaction forces and torques
Contact and lubricant film pressures, minimum lubricant film thicknesses, and friction losses
Shift paths and bearing eccentricities
Rotor movements and excitations (Campbell diagrams and waterfall plots for stability and NVH analysis)

In addition to the rotor dynamic and the bearing, focus can also be placed on the dynamic of other ETC components that can vibrate, such as the turbine-side bypass / waste gate level system. To this end, previously determined excitation forces are applied to the entire ETC system and analyzed.

With the help of the standardized co-simulation interface FMI (Functional Mock-up Interface), FEV Virtual Engine © also offers the option of carrying out coupled simulations with additional simulation tools – for example, using GT-POWERTM. As an example, the entire engine oil circuit is coupled with the ETC dynamic in order to represent even more detailed bearing effects through the oil supply.

More Information on Virtual Engine.