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A simple imaging technique was explored as a means for characterizing in-cylinder wall wetting in GDI engines. For technique development, a GDI fuel injector was directed vertically down on the top of a temperature controlled flat piston within a non-motored research cylinder in an experimental arrangement described previously [3, 4, 6, 7, 14]. A three-factor randomized factorial design of experiments was performed that included laser sheet level (with three treatments including 0 mm, 2 mm, and 5 mm from the piston surface), piston surface temperature (with three treatments including 100 °C, 150 °C, and 200 °C), and time after start of fuel (with five treatments including 1 ms, 2 ms, 3 ms, 4 ms, and 5 ms after start of fuel). The technique for characterizing wall-wetting differences involved subtracting the 8-bit pixel intensity values at every pixel location for one laser-illuminated scattered image from another image.

The instantaneous structure of sprays from two Direct Injection, Spark Ignition (DISI) injectors were studied within a non-motored research cylinder. In-cylinder conditions simulating injection up to 27° before top dead center (BTDC) were utilized in the characterizations. Comparisons between the two injectors highlight the impact of nozzle design on spray performance. Experiments include axial and horizontal flow visualization and PIV, illustrating the effect of in-cylinder density (with in-cylinder pressure used to control in-cylinder density) on instantaneous fuel spray structure. Fuel spray imaging experiments illustrate the effect of in-cylinder density on the initial clump of fluid and other spray development phases. In-cylinder density increases hollow cone narrowing and decreases spray penetration. PIV results show that the initial clump of fluid travels with extremely high velocities for all injection strategies.

Fuel spray imaging and PIV were used to investigate the effect of piston temperature and location on fuel spray structure and piston surface fuel impingement for three injection timings. Experiments were performed within a non-motored quartz research cylinder with in-cylinder densities and piston displacements that match those of a motored engine at the time of injection. Crank angles of 35°, 55°, and 75° before top dead center (BTDC) were considered, corresponding to in-cylinder pressures for the non-motored case of ∼5 atm, ∼3 atm, and ∼2 atm, respectively. A simulated piston was constructed of aluminum with controlled surface temperatures up to 210°C. The fuel spray was illuminated using single laser pulses formed into a sheet and passed through the cylinder with the images captured using a digital camera connected to an image acquisition board and computer.

A throttle control system has been developed for a small V-twin engine used in a hybrid AC power generation system. The control system utilizes a throttle actuator, a proportional integral derivative (PID) controller and software that determines desired power outputs (engine speeds) based on real-time measurements. The control system forms part of a hybrid power generation system that incorporates two time variable three-phase AC power sources: a wind turbine and an internal combustion engine-generator combination. Initial testing of the control system shows a stable response and a reasonable settling time for speed step changes when a minimum load is applied to the engine. A design methodology for throttle control system optimization is also described.

A liquid-phase port injection system for liquefied petroleum gas (LPG) generally consists of a fuel storage tank with extended capability of operating up to 600 psi, a fuel pump, and suitable fuel lines to and from the LPG fuel injectors mounted in the fuel rail manifold. Port injection of LPG in the liquid phase is attractive due to engine emissions and performance benefits. However, maintaining the LPG in the liquid phase at under-hood conditions and re-starting after hot soak can be difficult. Multiphase behavior within a liquid-phase LPG injection system was investigated computationally and experimentally. A commercial chemical equilibrium code (ASPEN PLUS™) was used to model various LPG compositions under operating conditions.