Numerical analysis of exhaust gas braking system to maximize the back pressure

The excessive load on foundation brakes are shared by exhaust brakes during downhill performance of trucks. The exhaust brake increases the life of foundation brakes and also provides assistance to the foundation brake, especially during downhill operation. In this work, the position of the exhaust flow flap have been optimized accordingly to increase the back pressure generated in the diesel engines manufactured at Tata Cummins Ltd., India. The exhaust valve lift with respect to crank angle is modified for exhaust brake module to facilitate back pressure inside engine cylinder. A 1-D GT-POWER six cylinder engine model is modelled to replicate conditions at the inlet of the exhaust circuit. CFD simulations are carried out for various exhaust flow flap positions in order to maximize the back pressure required at engine cylinder. The position of the exhaust flow flap is crucial in resulting back pressure as the exhaust elbow geometry have sharp bends and diverging cross section. The exhaust flow flap is always placed normal to the plane of exhaust elbow. Numerical simulations are performed for various position from the turbo fan. High absolute pressure is observed, when exhaust flow flap is moved closer to the turbo fan. The high absolute pressure at exhaust manifold inlet is observed at 27mm from the turbo fan. (paper)