Noise Radiation from Automotive Turbochargers
Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
Turbochargers are now commonly used in modern automotive engines, which increase the density of air entering the engine to produce more power. This device not only greatly improves the degree of engine efficiency, but also reduces the pollutant emissions. However, one of the important issues which must be considered is the noise from turbochargers. This noise can radiate either after propagation through the intake and exhaust ducts or via induced vibrations in the turbocharger housing. Here the in duct sound will be studied and normally this cause problems mainly on the intake side where there is less silencing available. In particular noise from high frequency tones as well as surge noise phenomena can cause noise problems.The main aerodynamic noise from centrifugal compressors are blade tone noise, buzz-saw noise and flow separation (or surge) noise. For instance the tones occurring at blade passing frequencies can be a problem for large turbochargers,e.g., as found on trucks, where they lie in the range around 10 kHz. The most efficient way to achieve quieter machines is the reduction of the sources, therefore it is important to be able to measure and investigate the sound generation ofturbo chargers.In this thesis work the sound generated has been investigated using a dedicated turbocharger acoustic test rig. The main purpose is to investigate methods for estimating the in-duct acoustic power using a micro-phone array. Three differen tmodels are proposed to estimate the power in the propagating acoustic modes and to suppress the flow noise. In order to test the proposed methods experiments have been performed on an automotive compressor at four different operating conditions. The results are compared with the literature in order to identify the dominating sound generation mechanisms.
Place, publisher, year, edition, pages
2011. , 33 p.
Trita-AVE, ISSN 1651-7660 ; 2011:44
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-39473OAI: oai:DiVA.org:kth-39473DiVA: diva2:439838
Subject / course
Degree of Master