Experimental GT-POWER Correlation Techniques and Best Practices Low Frequency Acoustic Modeling of the Intake System of a Turbocharged Engine 2017-01-1794

As regulations become increasingly stringent and customer expectations of vehicle refinement increase, the accurate control and prediction of induction system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace.

The goal of this project was to improve the predicative accuracy of a 1-D GT-power engine and induction model and to update internal best practices for modeling. The paper will explore the details of an induction focused correlation project that was performed on a spark ignition turbocharged inline four-cylinder engine.

This paper and SAE paper “Experimental GT-POWER Correlation Techniques and Best Practices” share similar abstracts and introductions; however, they were split for readability and to keep the focus on a single a single subsystem.

This paper compares 1D GT-Power engine air induction system (AIS) sound predictions with chassis dyno experimental measurements during a fixed gear, full-load speed sweep. The engine is a turbocharged, spark ignition I4. The air induction system includes an air box, centrifugal compressor, and charge air cooler. Engine performance predictions were first compared with measurements, in terms of brake torque and intake manifold temperature, to confirm that the model is capturing reduced performance during elevated air temperature in the intake manifold. Then, the GEM3D models of the air box and charge air cooler are discussed, along with the compressor acoustic model. The transmission loss of the air box is compared with experimental data. The predicted sound at the 2^nd and 4^th engine orders is compared with measurements, which shows reasonable agreement.

The primary takeaway from the project is the importance of correctly modeling the geometry in detail and matching the exact operating conditions between test and CAE.