Engineering

Turbocharging

FEV offers OEMs, suppliers, and turbocharger manufacturers a wide range of engineering services in the field of turbocharging for combustion engines and fuel cells. Thanks to many years of expertise in the areas of method development, simulation and testing, highly complex questions can be answered fully and in the shortest possible time. In addition to the measurement and evaluation of exhaust gas turbochargers, FEV focuses on the optimization of the interaction between combustion engine/fuel cell and their corresponding turbocharging system.

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

Design & development of turbocharging systems for mobile applications
Test capabilities of exhaust gas turbochargers and electrically driven turbocharging systems
1D & 3D simulation methods for optimization and analysis of aerodynamics and bearings
Acoustics of turbochargers (test and simulation)
Design & production of test benches for exhaust gas turbochargers, electrically driven turbocharging systems and their subcomponents
Support in the development of test procedures and test bench routines
Experience in solving turbocharging system problems (prototype and production applications)
Consulting in the field of turbocharging (matching, charging concepts, costs, ...)
Software tools and development of customer specific routines

Our capabilities

Testing Possibilities

In recent years, FEV has expanded its experimental capabilities to investigate 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, functional tests, thermodynamics, steady-state map measurement, extended turbine map measurement with RAM and CCL, measurements with vehicle package, component tests, investigations of variabilities, thermal shock, low-cycle fatigue of turbine and compressor, acoustics, pulsating admission with FEV PulseGen, quantification of the shaft motion, PIV measurements, bearing investigations with oil foaming ...)
Bearing friction test bench for turbocharger
(Bearing friction as a function of speed, axial thrust measurements on the hot gas test rig, quantification of the shaft motion, BlowBy measurement, quantification of the bearing bushing speed, ...)
Inertia test bench for turbocharger
Engine test bench
(Determination of efficiency level in combination with the engine, acoustic measurement, and endurance tests)
Special setups for further components of the air path as required
(electrical compressor, charging systems for fuel cells (scalable power supply and electrical measurement equipment), electrically assisted turbochargers (el. recuperation and el. charging possible), pressure tests as endurance runs for flow-guiding components (e.g. intake manifolds), measurements of exhaust systems, catalyst aging of gas engines, testing of burners for catalyst heating EU7, measurements of exhaust flaps and control elements, ...)

On the two combustion chamber test rigs, the maps of all turbocharging systems from the passenger car and commercial vehicle sectors can be measured separately and including the vehicle package up to a maximum exhaust gas mass flow rate of 1 kg/s. A map extension of the turbine is made possible by operation with a closed compressor circuit "Closed-Loop".

When investigating dual scroll turbochargers, it is also possible to measure the individual scrolls separately and to map partial admission conditions (including crossflow behavior). Targeted investigations with wastegate or turbines with variable geometry (VTG) and on individual components can also be carried out in endurance runs. Research investigations with optical and acoustic measurement methods are also part of the test portfolio. Please feel free to challenge us with your special request.

Benchmarking Process

FEV has developed a unique benchmarking process for the entire powertrain. Based on this, the largest database for automotive turbochargers could be generated. It includes data from 18 different turbocharger manufacturers from production, after market launch, and prototype data (status 02/2021). In total, more than 350 turbochargers were measured under the same boundary conditions and the same test setup, thus ensuring direct comparability of the measurements.

FEV is a trusted service provider for benchmarking programs of well-known turbocharger manufacturers and OEMs. Various design and performance aspects can be evaluated by programmed routines within the FEV turbocharger benchmark database. The customer can configure an evaluation package from over 70 possible comparisons in advance. In addition, FEV experts provide evaluation feedback on the analyzed turbocharger to support the development process and optimize the product.

The following analyses are available as examples. The following 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 a comprehensive portfolio of software tools to enable realistic modeling of turbochargers and to support the commercial engine design process, e.g. using GT-POWER™. Aerodynamic phenomena, bearing friction as well as heat transfer aspects are considered. Due to the optimal combination of in-house software development and validation on test benches, FEV models for gas exchange codes meet the high demands of today's development trends.

With the help of our in-house tool, TCConcepts concept studies for the turbocharging system can be carried out already at the beginning of an engine development. All common concepts, including multistage, variability, or electric or mechanical turbocharging, can be mapped. A key aspect here is that exhaust pulsation, which is essential for turbine operation, is not only mapped using correction factors, but is also calculated in full.

Our commercial software package TCTOOLS is used to prepare measurement and simulation data in advance of the gas exchange simulation. In an automated process, aerodynamic effects and heat transport can be separated in the efficiency calculation. Scaling of turbine and compressor (housing and wheel) is also possible to perform targeted parameter studies. The application portfolio is rounded off by a physics-based extrapolation tool that extends existing maps in such a way that the entire operating range can be fully simulated in charge change 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.