The high-speed movies available in this page are intended to provide support to the Fuel paper entitled “Microscopic investigation of the atomization and mixing processes of diesel sprays injected into high pressure and temperature environments” by Manin, Bardi, Pickett, Dahms and Oefelein (view full reference here). The operating conditions for these movies vary from low to high ambient temperatures and pressures such as those found in diesel engine near top-dead-center (Spray A conditions for instance). ECN Spray A injectors (210675 and 210370) have been used in this study. Note that many more experiments have been performed and the selection of high-speed movies available below only represents some of the best examples supporting the discussions to be found in the Fuel paper.

Long-distance microscopy (LDM) was used as the optical diagnostic to investigate the breakup and mixing of n-dodecane sprays injected into different ambient conditions. The axial and radial distances displayed in the movies are given in millimeters and the time is with respect to the start of injection and in microseconds. The quality of the movies is paramount to understand whether surface tension has an impact on mixing or not, hence, the circle of confusion, which has been computed for all the movies, is stated for each movie found in this page (likewise in the Fuel paper). Details about the experiments or the results and conclusions can be found in the aforementioned Fuel paper.

The table below contains movies of the first millimeter of the spray out of the injector nozzle hole while varying ambient pressure at low ambient temperature, as displayed in Fig. 5 in the Fuel paper.

 

Ambient conditions0.5 MPa – 440 K1.0 MPa – 440 K2.0 MPa – 440 K3.0 MPa – 440 K
Injector210675210675210675210675
Injection pressure [MPa]150150150150
Frame rate [kfps]156156156156
Resolution [µm/pix]4.74.74.74.7
Circle of confusion [µm]13141514
Movies: Play or Save0.5 MPa – 440 K1.0 MPa – 440 K2.0 MPa – 440 K3.0 MPa – 440 K

The movies in the table below show the first millimeter of the spray when ambient pressure is varied while the charge gases are at high ambient temperature (900 K), as shown in Fig. 6 in the Fuel paper.

 

Ambient conditions1.0 MPa – 900 K2.0 MPa – 900 K4.0 MPa – 900 K6.0 MPa – 900 K
Injector210675210675210675210675
Injection pressure [MPa]150150150150
Frame rate [kfps]156156156156
Resolution [µm/pix]4.74.74.74.7
Circle of confusion [µm]13151618
Movies: Play or Save1.0 MPa – 900 K2.0 MPa – 900 K4.0 MPa – 900 K6.0 MPa – 900 K

 

The high-speed LDM movies, shown in Fig. 7 in the Fuel paper, taken at an intermediate temperature (700 K) above the critical temperature and at pressures slightly above the critical point (2.0 MPa and 4.6 MPa), in which droplets and droplet formation can be observed are available, respectively, following these links: 2.0 MPa – 700 K and 4.6 MPa – 700 K. Note that these two experiments have been performed at different injection pressures, 50 MPa for the 2.0 MPa ambient pressure condition and 150 MPa for the 4.6 MPa case, while all other parameters displayed in the tables above were held constant. The circles of confusion for these two experiments were 14 and 19, respectively for the 2.0 MPa and the 4.6 MPa ambient pressure cases.

The movies in the table below show the mixing processes of the spray further downstream, around a location corresponding to the liquid penetration length under Spray A (approximately 10.5 mm from the orifice). Ambient pressure and temperature vary to show the persistence of droplets after the end of injection, when the conditions suggest that mixing is controlled by liquid breakup and droplet atomization, as shown (Fig. 8) and discussed in the Fuel paper. Note that these experiments have been performed with a different injector and a different optical configuration (Visualization window size and magnification).

 

Ambient conditions4.6 MPa – 700 K3.0 MPa – 900 K4.0 MPa – 900 K
Injector210370210370210370
Injection pressure [MPa]505050
Frame rate [kfps]213333
Resolution [µm/pix]121212
Movies: Play or Save4.6 MPa – 700 K3.0 MPa – 900 K4.0 MPa – 900 K