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Article Dans Une Revue Ingineria automobilului Année : 2014

Acoustic reflection at the intake of a turbocharged internal combustion engine: optimal geometry for low end torque consideration

Résumé

In order to increase the volumetric efficiency of downsized engines, turbochargers may be used. They allow the increase of the intake pressure and are associated with a charge air cooler (CAC). The main disadvantage of a downsized turbocharged engine (compared to a naturally aspirated one) is the deterioration of low-end torque caused by the lack of enthalpy of the exhaust gas at low engine speed and load. To investigate this issue, the intake line of a turbocharged Diesel engine was analyzed, focusing on the pressure waves at the inlet [1] [2] which are most often overlooked on these engines in favor of pressure loss reduction.A first step of the study is to identify the potential resonance for the establishment of standing waves at low engine speeds. Experimental tests with different pipe lengths upstream and downstream of the charge air cooler (CAC) were performed on an electrically driven engine test bench (pulse generator). This was done to study the influence of pressure waves on the air filling of the engine and determine the optimal length of the air circuit.In a second step, and to better understand the dynamic phenomena at the intake, the reflection coefficient at the interface of the CAC is calculated (method of pressure wave decomposition) from measurements on the engine test bench (with combustion). This allows to characterize the unsteady behavior of this element and to better discern the influence of the upstream and downstream ducts on engine filling.Finally, a new active system is proposed, it consists of a long pipe designed for acoustic tuning (low end torque) and a short pipe to minimize losses (high speed power generation). The acoustic response of this element is compared to that obtained with an equivalent length of straight pipe on the dynamic bench [3].
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Dates et versions

hal-01145195 , version 1 (23-04-2015)

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  • HAL Id : hal-01145195 , version 1

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H. Mezher, D. Chalet, J. Migaud, V. Raimbault. Acoustic reflection at the intake of a turbocharged internal combustion engine: optimal geometry for low end torque consideration. Ingineria automobilului, 2014. ⟨hal-01145195⟩
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