Analysis of the possibility of using acoustic emission for monitoring technical condition of the fuel injector in 3AL25/30 engine

Acoustic emission method (AE) can be used for the diagnosis of machine parts such as, for example: fuel injectors. This paper presents the methodology and research results of 3AL25/30 engine fuel injector. During research was studied one injector in good condition and second with simulated failure involving closing 2 of 9 holes of the injector tip. Research was carried out on a laboratory test stand using a set of acoustic emission Vallen System. This set included: 4 channel signal recorder AMSY 6, two measurement modules ASIP-2/S, preamplifier with a frequency range 20 kHz-1 MHz and the strengthening of 34 dB, AE signal measurement sensor type VS 150M, with a frequency range 100-450 kHz. During the study, the acoustic emission (AE) generated by tested injector was recorded. The following parameters were determined: amplitude, rise time, duration time, total time, number of events - hits, the effective value of the signal (RMS). Analysis of the results showed significantly longer total time of the injection in the case of damaged injector compared to the injector in good conditions. Signal amplitude was higher, however, the RMS signal reached approximately 3-times lower value for the injector with damaged tip. This means lower quality fuel atomization. Laboratory test results were compared with signals recorded on injectors installed in the engine. Analysis of the signals allowed detection damage of the injector installed in the engine during normal operation.