Tryckpulsgenerering för funktionskalibrering av mätsystem
The running of gas turbines with low emissions causes high pressure pulsations to arise in the combustion chamber. These pulsations are high amplitude sound vibrations. At some frequencies these are harmful to the gas turbine. Hence these pulsations are monitored to avoid operating conditions where pulsations are specifically harmful. It is necessary to expose the system of known pulsations to verify the functionality of the monitoring process. This report describes the development of a generator of pressure pulsations to verify the monitoring system. The output should be of harmonic form with a frequency of greater than 160 Hz and 15 mbar in amplitude. To begin with, a few alternatives to a pulsation generator are described. In light of studies of these possibilities the alternative based on a roller bearing is selected. This is considered as one of the easier alternatives to design. An existing generator of pressure pulsations has been analyzed. The calculations from this analysis supported the construction of the new device. The new generator far exceeded the specification regarding frequency, amplitude and harmonics of the pulsations. With a few modifications, such as encapsulation, the pulsation generator will be ready for usage. It could then serve as a mobile device for the inspection of the pulsation monitoring system. Possibly the device could be equipped with a faster and stronger motor. This would permit the device to be used for the calibration of pulsation monitoring sensors.