The schlieren method is a powerful and widely used technique for studying ignition and combustion. Jointly with high-speed photography, this method is often used in both SI- and CI-engines and combustion bombs, including rapid compression machines (rcm). This paper describes tests carried out on a new hydraulically actuated dynamic combustion rig, using schlieren visualisation in two orthogonal directions. The working principle of the rig is briefly described.
Results are presented on ignition properties of low quality gas blends using spark ignition and pilot flame. Methane, ethane and nitrogen were blended at different air-fuel ratios and tested as to ignition and early flame development.
For spark ignition tests, the pair of images from the two orthogonal directions enables the use of digital image processing to calculate the flame speed, and to compose a three-dimensional volumetric image of the flame front shape. The extra information gained by visualisation in two directions increases the statistical accuracy and the understanding of the ignition process.
Tests carried out on the rig clearly demonstrate the value of the set up as tool for investigations of injection and ignition properties of fuels.