Study of Junctions in 1-D & 3-D Simulation for Steady and Unsteady Flow
2010 (English)In: SAE International Technical Paper, no 01-1050Article in journal (Refereed) Published
In this work a comparative study between 1-D and 3-D calculations has been performed on different junctions. The geometries are a 90° T-junction with an area ratio of unity and a 45° junction with an area ratio of 1.78 between the main pipe and the side branch. The latter case had an offset between the centerlines of the main and the branched pipe. The 3-D modeling framework uses the Reynolds Averaged Navier-Stokes (RANS) equations with the k-ε model both for the steady and the unsteady flow cases. The comparison is made both under steady and pulsating flow conditions. The aim has been to assess the 1-D/3-D differences in terms of measures for flow losses.
There are large discrepancies between the 1-D and 3-D computed losses in junctions. The relative differences between 1-D and 3-D computed losses in isentropic power are 63 % and 175 % for the 90° and the 45 ° junctions without including the losses in downstream pipe legs. These figures are reduced to 12 % and 114 % respectively when including a straight pipe segment of one diameter downstream of the junction outlets.
For the 90° junction at pulsating flow, the discrepancy in 1-D and 3-D computed loss is lower compared to the steady flow case if comparing only the losses in the junction, but similar to the steady discrepancy if including the downstream pipe losses. For the 45° junction, the discrepancies are much larger. The 1-D loss is near six times that of the corresponding 3-D value if comparing the losses in the junction alone, and 3 times the 3-D value if including the losses in 10 diameter of the outlet pipe.
Place, publisher, year, edition, pages
2010. no 01-1050
IdentifiersURN: urn:nbn:se:kth:diva-24682DOI: 10.4271/2010-01-1050ScopusID: 2-s2.0-84877210948OAI: oai:DiVA.org:kth-24682DiVA: diva2:352687
QC 201009222010-09-222010-09-222010-09-22Bibliographically approved