Abstract
In certain running zones of naturally aspirated Diesel engine, the filling deficit is responsible for increases in pollution. Soft supercharging decreases pollution, by means of a turbocharger, and induces a slight performance improvement. This type of supercharging rises the air mass admitted by the engine, due to a compressor with weak pressure ratio. The engine mechanical load remains acceptable, it only requires some minimal modifications. Based on tests, the compressor's feasibility study was carried out on standard turbochargers. Guided by a quasi one-dimensional modelling, the experimentation has consisted of varying different geometric elements of the compressor. The result is the design of a soft supercharging compressor, whose efficiency remains reasonable in engine running range.