Optical gasoline DI single cylinder engine

The Hydra 1 engine test cell is utilised for fundamental studies of in-cylinder air, liquid and vapour fuel mixture preparation characteristics in modern combustion systems. Laser Doppler anemometry (LDA) and phase Doppler anemometry (PDA) are applied to airflows and fuel sprays within the cylinder under motored engine operation.

Several means of optical access to the chamber are available. These include fused silica piston windows, cylinder liners, cylinder bore annular sections, spark plug windows and a specifically modified 'three-windowed' cylinder head that allows access to the pent-roof of the chamber. In addition, the study of fuel injector characteristics is realised within a quiescent, atmospheric pressure chamber.

Optical GDI single cylinder engine

Hydra 1: an optical gasoline direct injection single cylinder engine

Research studies

Air and fuel mixing characteristics are studied using planar laser induced fluorescence (LIF) and Mie scattering of the fuel liquid and vapour phases. The single cylinder Ricardo Hydra 1 engine with gasoline direct injection (GDI) cylinder head has been the subject of intensive research.

Studies have included in-cylinder LDA and PDA, high-speed shadowgraphy, schlieren photography and video, and qualitative LIF for part and full load injection scenarios. More recently, a comprehensive programme was introduced to enable 'in-situ' calibration of fluorescence signals for differing homogeneously mixed equivalence ratios with differing crank angles throughout the engine cycle. Composition of the in-cylinder fuel and dopant concentrations was monitored continuously using gas chromatography. The sets of calibration curves were then used to quantitatively assess the vapour distribution of fuel present in the chamber under realistic engine operation.