Premixed- and Diesel-mode Liquid Penetration and Spray Dispersion for the Rotating Injector based on Imaging in an Optical Engine 2000-01-2862
A diesel fuel injector has been modified to allow rotation around its axis, driven by an electric motor. The injector was operated up to 6,000 rpm in the current study with a naturally aspirated, optically accessible AVL research engine.
The effects of injector rotation on the liquid penetration and dispersion of the spray have been investigated by imaging of Mie-scattered light and flame luminosity. Ambient gas conditions are indirectly controlled by choosing start of injection. Injection timing was set to -45° (premixed-mode), -13° and 4° ATDC.
The images show that the spray development is profoundly affected when going from a normal static position of the injector to a rotating movement. Unique liquid cascading phenomena were observed.
Injection during the compression stroke into air of low temperature and density shows that the liquid spray tip penetration is unaffected within the field of view (35 mm radius). Enhanced dispersion is obtained however. Considerable amount of fuel is shed off the penetrating spray and left behind, slowly drifting where the spray core has swept.
Injection under normal vaporizing conditions close to TDC shows that the rotation leads to significant shorter liquid penetration. This was attributed to enhanced air entrainment into the spray.