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Spray angle and penetration length data were taken under cold start conditions for a Direct Injection Spark Ignition engine to investigate the effect of transient conditions on spray development. The results show that during cold start, spray development depends primarily on fuel pressure, followed by Manifold Absolute Pressure (MAP). Injection frequency had little effect on spray development. The spray for this single hole, pressure-swirl fuel injector was characterized using high speed imaging. The fuel spray was characterized by three different regimes. Regime 1 comprised fuel pressures from 6 ? 13 bar, MAPs from 0.7 ? 1 bar, and was characterized by a large pre-spray along with large drop sizes. The spray angle and penetration lengths were comparatively small. Regime 2 comprised fuel pressures from 30 ? 39 bar and MAPs from 0.51 ? 0.54 bar. A large pre-spray and large drop sizes were still present but reduced compared to Regime 1. The spray angle and penetration lengths were typically larger then in Regime 1. Regime 3 comprised fuel pressures from 65 ? 102 bar and MAPs from 0.36 ? 0.46 bar. The fuel spray had a fully developed hollow cone structure with recirculation vortices at the edges of the spray, which constricted the spray angle. The spray angle was similar to Regime 2, while the penetration length increased. The pre-spray and drop size were reduced compared to Regime 2. In all regimes, decreasing MAP enlarged the spray angle, while injection frequency was not a significant factor.

As automotive torque converters decrease in both diameter and axial length, the effects of cavitation in the torque converter becomes increasingly important on noise, efficiency, and performance goals. Cavitation is the formation and collapse of vapor bubbles in a working fluid when local static pressure falls below the vapor pressure of the working fluid. A technique to detect cavitation in automotive torque converters using nearfield acoustical measurements is presented. The technique concentrates on high frequency noise that is associated with the collapse of vapor bubbles. The nearfield acoustical technique is compared to two other techniques using static pressure measurements inside the torque converter; one on the torque converter stator blades and the other on the torque converter pump blades. A microwave telemetry transmitter was used to obtain data from inside the torque converter in both previous investigations. The nearfield acoustical technique is demonstrated to be valid on a torque converter dynamometer test stand and in the bell housing of an operating vehicle. Using the nearfield acoustical technique, the effects of temperature and charge pressure on cavitation are shown. These effects are shown to agree with typical cavitation behaviors. The results for different performance torque converters are compared in the vehicle and on the dynamometer test stand. The results from in-vehicle tests show the same trends as test stand results. The nearfield acoustical technique provides a simple, relatively inexpensive procedure that can be utilized on a test stand as well as in the vehicle to determine the onset of cavitation in automotive torque converters.