Of great relevance today, from both the engineering and the environment points of view, are all the hi-tech procedures aimed at reducing the impact that the internal combustion engines have as a consequence of their emissions in terms of noise and pollutants. These procedures include: advanced computer simulations of the thermo-gasdynamic and structural characteristics of each component and assembly of the engine, and the related analysis of the most advanced technologies of containment of both kinds of pollution. Within B.R.D. R&D activity, high priority is granted to the analysis of every single aspect of the thermodynamic section of internal combustion engines. This side of the activity ranges from applied gasdynamics, heat exchange processes, computational gasdynamics, computer aided modeling and design. The advanced activity specifically concerning modeling, simulation and experimental validation of acoustics and thermo-fluidodynamic phenomena in internal combustion engine is fully executed in house thanks to dedicated softwares developed by B.R.D. and B.R.D.'s own test department.

To our clients this ensures that our projects are developed on the basis of the deepest, most advanced analysis procedures available to define each component to the last detail in order to automatically achieve maximum individual quality per each unit produced, and with higher productivity thanks to the reduced need for quality controls throughout the production process. This also ensures deep, precise knowledge of how the systems will respond and thus the capability to analyze in advance their maintenance needs.

COMPUTER AIDED MODELING AND SIMULATION OF ACOUSTIC AND GASDYNAMIC PHENOMENA IN COMPLEX SYSTEMS

The simulation is executed using a numerical code based on the “method of characteristics”. Thanks to this, it is possible to accurately evaluate: the noise intensity emitted by the inlet and exhaust ports by frequency bands and in both dB and dBA, the amount of noise pressure, the velocity and the pressure of the waves at each given cross section of the system, the transmission loss and the frequency response function of every acoustic system included in every given prototype under evaluation.

Optimization of mufflers

Example 1

Muffler	Mathematical modeling of muffler

Direct comparison by superimposition of the frequency response function obtained by live test and of the theoretical curve previously plotted by the simulation executed with the software developed within B.R.D. on the basis of the “method of characteristics”:

Comparison of simulated and experimental Frequency Response Function

Example 2


Predicted FRF of the silencer

Example 3


Silencer type 2

COMPUTER AIDED DESIGNING OF INLET AND EXHAUST SYSTEMS FOR INTERNAL COMBUSTION ENGINES

Correctly designed and dimensioned induction and exhaust systems produce tangible, positive effects on the quality of internal combustion engines in terms of both reduced emissions of pollutants and enhanced thermodynamic efficiency. Determining in advance the acoustic and fluidodynamic response of these systems in terms of efficiency and noise suppression represents a fundamental element in the designing of internal combustion engines in order to achieve optimum engine performance, thru effective scavenging capability in combination with proper sound emission.
The simulation is conducted using a numerical code based on the “method of characteristics”, which is fundamental in defining the intensity of the noise emissions from the inlet and exhaust ports, in frequency band and in dB and dBA. It also defines the intensity of noise pressure, the velocity, and the pressure in any given cross section, the transmission loss, and the frequency response function of each acoustic system included in the prototype under evaluation. The simulation also determines the amount of the gas flow mass and thus the volumetric efficiency of each cylinder, individually.
In addition, the simulations conducted using this proprietary B.R.D. software also plots in advance the shape of the pressure waves generated at the inlet and exhaust ports, thus allowing to evaluate in advance the quality of the noise that that given engine will produce and, in case, take proper action to modify the characteristics of the components of the system.

Example 1 Mathematical model of intake and exhaust system
Comparison between measured and calculated inlet port pressure	Noise emitted from inlet and exhaust open ends at 7.5 m at 2700 rpm

Example 2 Mathematical modeling of a complete induction and exhaust system
Noise spectrum at 4000 rpm.	Volumetric efficiency