L52331 Exhaust Manifold Design Guidelines to Optimize Scavenging and Turbocharger Performance

To develop the requisite air flow rate, the turbocharger must operate at a relatively high efficiency. But as important, the system pressure losses must be minimized to optimize turbocharger operating flexibility so that the turbine can produce sufficient power to operate the turbocharger compressor. The relationship between the various pressures and pressure losses throughout the turbocharged engine system, the turbocharger overall efficiency, ambient conditions, and the required turbine inlet temperature for sustainability is rooted in fundamental thermodynamic principles. The goal of the Exhaust Manifold Design Guidelines project was to investigate the NOX reduction role played by the exhaust manifold by exploring the impact of the exhaust manifold design on turbocharger and engine operation, as well as utilizing the abundant sets of field test data already provided by Hoerbiger Engineering Services (HES). For this project, exhaust manifold performance was defined as the capacity of the exhaust manifold to: 1) optimize cylinder scavenging efficiency; and 2) minimize the pressure differential between the compressor discharge and the turbine inlet.