Experiments on Wave Transmission and Reflection by Turbochargers in Engine Operating Conditions 2006-01-0022

An extensive experimental study is described whose main objective is to characterize the acoustic and flow dynamic response of turbocompressors to flow pulsation from a four cylinder high speed direct injection (HSDI) diesel engine. Four different turbochargers with centrifugal compressors of different size were considered, each one with a different turbine. Compressors were excited with pulsating flow in real engine conditions. Wave decomposition was used to obtain incident and reflected pressure perturbations upstream and downstream of the turbochargers, which allowed determining the zones of the compressor charts where they are more permeable to pressure oscillations, and to study the correlation of these magnitudes with turbocharger operating conditions. The results obtained are useful to determine in which conditions the pulses passing through the compressor can cause relevant noise emission, and to establish their eventual relevance regarding the use of the length of the ducts upstream of the compressor for engine tuning purposes.