Effects of Pulsating Flow on Exhaust Port Flow Coefficients

Paper #:
  • 1999-01-0214

Published:
  • 1999-03-01
Citation:
Bohac, S. and Landfahrer, K., "Effects of Pulsating Flow on Exhaust Port Flow Coefficients," SAE Technical Paper 1999-01-0214, 1999, https://doi.org/10.4271/1999-01-0214.
Pages:
13
Abstract:
Five very different exhaust ports of diesel and gasoline engines are investigated under steady and unsteady flow to determine whether their flow coefficients are sensitive to unsteady flow. Valve lift is fixed for a specific test but varied from test to test to determine whether the relationship between steady and unsteady flow is lift dependent. The pulse frequency is chosen to correspond to the blow-down phase of an engine running at approximately 6000 rpm, but the pressure drop across the port is much smaller than that present in a running engine. Air at room temperature is used as the working fluid.It is shown that unsteady flow through the five exhaust ports causes, at most, a 6% increase or a 7% decrease in flow coefficient. When the change in flow coefficient for a given exhaust port is averaged over the range of valve lifts most important in determining engine performance, the average increase in port flow coefficient ranges from 0.5-2.5% which only minimally affects engine performance. This finding affirms that it is reasonable to measure exhaust port flow coefficients under steady flow conditions and then use these flow coefficients in gas exchange simulations to optimize valve timing and the exhaust manifold for state of the art flow efficiency under running engine conditions.
Access
Now
SAE MOBILUS Subscriber? You may already have access.
Buy
Select
Price
List
Download
$27.00
Mail
$27.00
Members save up to 40% off list price.
Share
HTML for Linking to Page
Page URL

Related Items

Training / Education
2018-03-26
Technical Paper / Journal Article
2010-10-25
Training / Education
2017-12-18
Training / Education
2018-05-07