Exhaust Tuning of Large-Bore, Multicylinder, Two-Stroke, Natural Gas Engines

In this paper, computational modelling of the exhaust system of two types of large-bore, multicylinder, two-stroke engine is performed. The airflow performance of a four-cylinder V-bank Cooper GMV-4TF engine and a six-cylinder in-line Clark TLA engine is simulated. The simulation includes the computation of pressure wave propagation in the exhaust manifold. Using a modified method of the steepest ascent numerical technique, tuned exhaust manifolds are designed for each engine with the objective of reduced NO emissions. The NO reduction is accomplished by increasing the trapped cylinder mass and correspondingly reducing the peak combustion temperature. The simulations predict NO reductions in the range 10–30 per cent as a result of exhaust tuning.