MTV Measurements in Internal
Combustion (IC) Engine

Harold Schock, Manooch Koochesfahani, Gregory Baker, and Daniel Nocera
Instantaneous realizations (left two images) and the ensemble average (right image) of velocity and vorticity fields at 270 CAD and 1500 rpm. Blue and red indicate cw and ccw vorticity, respectively.
The development of Molecular Tagging Velocimetry (MTV) in the Center is allowing us to study the dynamics of flow in motored IC engines operating under realistic conditions. The whole-field maps of the velocity and vorticity fields shown here are for a tumble plane that bisects the intake and exhaust valves. The measurements are at 270 crank angle degrees (CAD), midway through the compression cycle in the engine. The large degree of cycle-to-cycle variation in the flow field, clearly depicted in the two instantaneous realizations, limits the performance of an engine. The ensemble-averaged velocity field has little resemblance to the instantaneous flow and any predictions of mixing and combustion based on the average field will be seriously flawed. Data such as these are being used to help develop appropriate predictive models for IC engine flows.