Exterior noise-level measurements were conducted on a typical in-service diesel engine heavy-duty truck to determine the noise-level reduction resulting from a turbocharger retrofit. The tests were conducted in accordance with procedures recommended by the Society of Automotive Engineers and the United States Department of Transportation. Overall noise-level measurements and a narrow-band spectrum analysis indicate that a significant noise-level reduction is obtained from the installation of a turbocharger kit. The lower noise level is the result of a decrease in the exciting forces due to combustion. The narrow-band analysis shows a significant amplitude reduction at the engine firing frequency and an overall spectrum reduction.
Detailed tests were conducted on standard shape axial flow fans as well as blades with tip treatment. The object of the tests was to determine the optimum tip configuration. To evaluate the effect of changes in trip clearance, the tests were performed with a blade to shroud clearance of 0.5 and 0.75 in. All other system and environmental factors were held constant. The test facility was designed to standards based on a recently developed induct sound power measuring system which includes a measuring section for fan performance measurements, a microphone system consisting of a microphone with attached sampling tube developed to handle crossmodes and suppress flow noise, and a nearly anechoic termination to deal with the problem of end reflections. The measured data compares aerodynamic performance, specific sound characteristics, radial distribution of velocity components, and the noise spectra at various operating conditions. The results indicate that fan tip design has a significant influence on fan performance and fan noise.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.