Matching of High-Output Turbocharged Engines for Maximum Torque Backup and Emission Reduction Based on the Use of Variable Geometry Compressors and Turbines

Turbine performance programs based on relatively simple one-dimensional considerations of great value when investigating the effect of variable nozzle angle or turbocharger matching, and compressor programs based on a combination of one-dimensional flow formulations for rotor and diffuser are discussed. A complete survey has been carried out and the results show that by use of optimized turbine nozzle angle and compressor prewhirl schedules, a fueling schedule appropriate to high torque backup at just over half engine speed can be employed without exceeding the operating limits of the engine with respect to air/fuel ratio (A/F), exhaust temperature, or maximum cylinder pressure.