Abstract:
The reduced exhaust emission requirements and engine installation constraints suggest that the turbine for the next generation of turbocharged automotive diesel engines must be highly loaded, i.e., with high expansion ratio without an increase in the rotational speed. This approach means that the peak efficiency must be obtained at lower velocity ratio, U/Cis, than are common with customary radial-inflow turbines. This can be achieved with a mixed-flow rotor with positive blade angle. Two mixed-flow rotors, which have identical dimensions but differ only in their blade leading edge, camber line and rotor length, were tested under steady state conditions with same housing. This paper compares the performance results of these two turbines and demonstrates the importance of the blade geometry. In practice, both attained peak efficiencies at lower U/Cis, with 'constant blade angle' design more efficient than the notionally 'constant incidence angle' design rotor. In addition, measurements of wall static pressures upstream of the rotors and along the blade shroud provide some important information regarding the qualitative assessment of rotor losses, and upstream and downstream conditions of the rotors.
Page(s):
145-164
DOI:
DOI not available
Published:
Journal: Journal of Engineering and Applied Sciences, Volume: 17, Issue: 1, Year: 1998