Dynamometer testing of the Z engine

The dynamometer and measurement installation of the prototype was build in the facilities of VTT (Technical Research Centre of Finland) in the engine power technology department during Marsh and April 2004. The first dynamometer tests were carried out in April.

The measurement installation is build in a climate controlled dynamometer room, that is normally used for cold tests of engines. In these measurements however, the environment temperature is normal room temperature. The dynamometer brake and the engine are situated in two different rooms. The dynamometer driveshaft is connected to the engine through the wall. The installation in the engine room is presented in the figure 1.

Figure 1: The engine and part of the measurement installation.

Figure 2: The data acquisition for cylinder and fuel pressures.

The following measurements are in use at the moment: intake air temperature, intake air pressure, intake air mass flow, exhaust gas temperature, cylinder head cooling fluid temperature, exhaust gas composition (O₂, HC, CO, CO₂), fuel consumption, brake torque, engine speed, cylinder pressure, fuel injection pressure and crankshaft angle. The cylinder pressure and the fuel injection pressure curves are acquired with the fast data acquisition module connected to the laptop computer (figure 2). Other data is collected either manually or by the data acquisition system of the dynamometer room. The external compressor produces intake air pressure during the measurements. The intake mass flow and pressure are measured and the power consumption to make the needed compressed air is then calculated.

During the measurements, different parameters have been tested for the camshaft timing, fuel injection timing and intake air pressure. Some modifications have been done to the fuel injection system. The most significant changes have been done to the piston. The first version of the combustion chamber (figure 3) is made of aluminium and copper (the combustion chamber lip). The second version of the combustion chamber (figure 4) is insulated and it is made of heat-resistant steel (Nimonic 75). The last version (figure 5) of combustion chamber has rugged surface for making the evaporation surface larger and some shapes for increasing turbulence.

Figure 3: The first version of the combustion chamber.

Figure 4: The piston with insulated combustion chamber.

Figure 5: The insulated combustion chamber with rugged surface quality after use.