Exploratory Development of a Twin-Spool Turbocharger for a High Output Diesel Engine
Final rept. Sep 1983-Jun 1986,
THERMO MECHANICAL SYSTEMS CO CANOGA PARK CA
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The analysis, design, fabrication and experimental testing of a twin spool turbocharger was conducted for the Cummins NTC-475 diesel engine. Two major designs of the twin-spool turbocharger were fabricated and tested 1 Compact design, concentric shaft-to-shaft bearing coupled turbocharger incorporating a split 40 deg backswept impeller, b split AiResearch Ti8A85 turbine rotor, c adjustable vaned compressor diffuser, and d nozzleless AiResearch turbine volute housing and 2 Independently supported shafts dynamically de-coupled concentric shaft design incorporating a separate structures for bearing support of the inner shaft b split 25 deg backswept compressor impeller, c split T18A40Ti8A85 turbine rotorexducer combination, and d divided volute, adjustable nozzle turbine housing. While bench tests were performed on both designs, engine testing was successfully carried out using the latter designs. Tests indicated that the second twin-spool configuration gave performance comparable to the originally equipped two-stage turbocharger system of the NTC-475 diesel engine rated BHP of 425 hp at 2100 RPM, best BSFC of 0.35 at engine lug with the added benefit of extending engine lugging range to 1200 RPM from 1300 RPM, as originally equipped. This configuration gave peak compressor efficiency of about 75 and peak turbine efficiency of about 80, both attributed to the reduction inducer angle of attack and exducer exit swirl angle made possible by the twin-spool concept.
- Hydraulic and Pneumatic Equipment
- Jet and Gas Turbine Engines