Abstract: A method and apparatus is provided for the sensing, collection, and analysis of information on combustive and mechanical events occurring within an operating internal combustion engine through the measurement of mechanical stress waves present within the engine. The system includes a magnetostrictive sensor placed in mechanical compliance with the engine, preferably the engine block, which detects and translates stress waves into an electrical signal that is filtered and amplified for recording and/or for analysis. Information regarding the frequency, amplitude, and timing changes within the signal is utilized to characterize the ordinary operation of the engine and to identify anomalous events. The system includes a means for maintaining a signal record and comparing signal features with past records for a particular engine or with standard signal features associated generally with certain engine events.

Abstract: A plurality of piezoelectric sensors are disposed in a spatial array around the ports of an injection nozzle. Separate electrical signals proportional to the instantaneous momentum of fluid discharged from the injection nozzle and impacting on each of the sensors are used to calculate the instantaneous momentum and mass flow rate of fluid impacting each of the sensors.