The automotive industry is facing stricter carbon regulations and emission standards. Modern combustion processes place increasing demands on charge motion in the cylinder. For example, requirements differ significantly for a turbo-charged, direct-injection gasoline engine as compared to a naturally-aspirated engine with port-fuel injection. Novel combustion processes with early or late intake valve closing extend the parameter space even further.
A needs-based assessment of the charge motion is made possible with flow test rigs that are developed at FEV, both for the development process as well as for end-of-line testing. “Our flow test benches are the product of over 30 years of research and experience in both engine development and sales of the corresponding testing tools”, explains Bruno Funken, Technical Specialist Custom Test Benches at FEV. “Each test bench is precisely adapted to meet the customer’s requirements and is delivered as a final, turnkey product.”
FEV flow test benches enable the analysis and assessment of cylinder-head flow, tumble, and swirl performance under steady-flow conditions. This represents an indispensable tool for port development and quality assurance. The fundamental concept and detailed solutions are based on many years of experience in FEV’s flow laboratory. When linked to the FEV database, the measured ports can be evaluated in scatter bands and, from this, basic correlations of the combustion behavior can be derived.
The Testing Setup
The test bench consists of four major components:
- Frame with cylinder head pick-up and automatic valve adjustment
- Blower unit with flow measurement system
- Measurement system for determining charge motion (swirl and tumble paddle wheel; swirl and tumble honeycomb)
- Control box with integrated measurement instrumentation and special measuring software
Various types of paddle wheel and honeycomb measurement devices can be combined for testing, depending upon customer requirements. The measuring tubes feed into a generously-sized expansion tank that ensures defined flow conditions and compensates for flow pulsations. The blower unit is designed to be a stand-alone system and consists of one or two side channel blowers, frequency converters for the automatic regulation of flow rate, and a rotary gas meter to measure the volume flow. The data acquisition card is housed in a separate control cabinet that also contains the controls for the valve actuators and connectors for the frequency inverter and sensors. Combined with the software (LabVIEW), automatic adjustment of the valve lift allows for fully automatic flow measurement.
For measurement, the cylinder head is connected to a replaceable cylindrical tube with the same diameter as the bore in the engine. The charge motion (tumble or swirl) is recorded using the rotational velocity of the paddle wheel or the torque of the honeycomb.
The steady-flow test bench facilitates testing of engine-like flow conditions at the inlet and outlet ports under steady-flow conditions and thus allows for the targeted assessment of the flow, tumble, and swirl performance of the cylinder head, which are typically presented as dimensionless numbers. The FEV database is used to design and assess intake and exhaust ports based on scatter bands.