Experimental Investigation of the Transient Performance of a Turbocharged Compression Ignition Engine at Different Operating Conditions

In this work, an experimental investigation was conducted in order to study the transient performance of turbocharged compression ignition engine at different operating conditions. The experimental work was performed on a test rig comprising a four stroke 5.67 liters water-cooled turbocharged compression ignition engine and a Heenan hydraulic dynamometer. Instrumentation included devices for measuring engine speed, load, exhaust smoke level, exhaust temperature, fuel pump rack travel, turbocharger speed, and inlet air manifold pressure. The test facility was provided with a computer controlled data acquisition system to enable fast and accurate measuring and evaluating the engine response to sudden demand of increased load or speed. Two groups of tests were carried out. In the first group, the transient response of the engine to sudden acceleration demands was measured. During these tests, the dynamometer water flow rate was kept constant at pre-adjusted values namely 0, 10, 20, 30 and 50 % of the engine full load then the engine was accelerated from the initial speed of 1000 rpm to the target speed by quickly moving the fuel pump control lever forward to its maximum travel position. Measurement of the engine response to the sudden increase in
dynamometer load was performed in the second group of tests. The fuel pump control lever was locked at its initial setting at initial speed of 2000 rpm and initial load of 20, 30, 40 and 50% from the engine full load then the load was increased suddenly to its maximum value. It is shown that the response time at which the engine speed reach to the desired value
correspond to full fuel pump rack position increases with the increase of the initial brake torque. Very slow response was noticed at initial loading of 30 and 50% this due to the increase of resisting load quickly to a higher value which suppresses the engine speed increase due to the decrease of the surplus torque (engine minus resisting torques). During
load acceptance tests it was shown that as the initial load decreases , „harder‟ turbocharger lag period, lower air–fuel ratio, higher crankshaft deceleration and lower engine speed were obtained, Which initiate larger governor displacement which increase the amount of fuel injected to increase the fuel load to the desired full load conditions