High Output Compound Diesel Engine Schemes - How do they Compare with State-of-the-Art Turbocharged Engines?

The paper is divided into two main parts.

In the first part, section 2 and 3, the performance of turbocharged and compounded systems based on a hypothetical 6 cylinder, 8 litre, 4 cycle DI Diesel engine is discussed under two subheadings:

1. a)
   the comparative performance, at rated conditions of 2200 rev/min of the two types of system operating at boost levels of 3 bar and 5 bar.
2. b)
   a much more detailed comparison of the two systems over the full speed range, at the same rated levels of boost, with the 3 bar system operating with a single stage turbocharger, and the 5 bar system with a 2 stage turbocharger.

In the second part, sections 4 and 5, the principle of the differential compound engine (DCE) as an integrated engine-transmission system is briefly described, followed by a comparative performance assessment of two alternative builds, both again using a 6 cylinder, 8 litre DI Diesel engine, in either 4 cycle or 2 cycle form, together with the results of a design study for a 1000 hp military engine.

In the concluding section 6 the outstanding torque-speed and transient performance characteristics of the DCE are set against the background of the inevitable compromises involved in using high pressure air not only as the working fluid for the engine, but also for the continuously variable transmission.