Chris weston
We've been waiting for someone like you to enhance our knowledge of the 'phenomonen' of cavitation of our high pressure fuel pumps. But then you confuse us by introducing Mr and Mrs without explaining what that happens to be. Help!!
I know a little more than most about cavitation having been triggered into researching the subject after having an irretrievable flame out on a Canberra's left Avon engine followed by the loss of the remaining right engine on short final. Fortunately we just made it to the under run and rolled out on the runway, much to the relief of the nav who had been tempted to leave via his ejection seat. But that incident was caused by the failure of all four variable stroke piston pumps which rapidly disintegrated when they started to pump water instead of fuel. There were some signs of earlier cavitation damage discovered.
Experience in those days soon revealed that short periods of operation of the HP pumps at high altitude soon had HP pumps cavitating and then we were learning that jet fuel starts to boil/gassify/produce vapour as the suction side of HP pumps reaches some low value not far above a vacuum. Presumably there will be a temperature variable.
I asked in a previous post whether anyone could produce some feel or appreciation for the likely pressure below which one could expect cold fuel, with some water content, to start vapourising which would consequently mark the onset of HP pump inlet cavitation. Such a number will set a bench mark as to the extent of fuel flow restriction necessary to substantially reduce output flow.
I would expect that fuel cavitating at the pump intake would instantly return to total liquid at the considerably higher pressures at its outlet with its flow then moderated by the FADEC demand.
Can you elaborate and give us an enhanced comprehension as to the operation of the conventional HP pumps particularly under marginal conditions.
Apart from opening up further instructive speculation this will prompt pilots to a better appreciation of the train of events which result when they move those thrust levers and the booster pump switches.