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Study and Control of Surge in Centrifugal Compressor. Assaad Krichene Dr. Yedidia Neumeier Dr. J.V.R. Prasad November 30, 1999. Outline. Controller Essentials Extension to Axial Compressor Modeling of the Precursor Waves Future Research - Centrifugal Compressor
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Study and Control of Surge in Centrifugal Compressor Assaad Krichene Dr. Yedidia Neumeier Dr. J.V.R. Prasad November 30, 1999
Outline • Controller Essentials • Extension to Axial Compressor • Modeling of the Precursor Waves • Future Research - Centrifugal Compressor • Future Research - Axial Compressor
Controller Essentials • Use only one pressure transducer at the inlet of the compressor • Use a real-time observer that identifies the frequency and amplitude of the pressure signal • Set an alarm signal when precursor waves are identified
Controller Essentials (Contd.) • Use a very simple control scheme based on the alarm signal • Vary the rate of fuel flow or the throttle opening to reject or suppress the stall • Can suppress the stall but also reject it • Recover the maximum plenum pressure • Require no information about the compressor characteristic map
Data Acquisition Computer Pressure Transducer Pressures Pressure Measurements Control Variables Throttle Valve Inlet pressure readout Control Computer Self entraining combustor Frequency/Amplitude Observer servomotor Control Law servomotor Fuel Valve Throttle and Fuel Valve Commands Controller Essentials (Contd.)
Extension to Axial Compressor • The connections to the axial compressor facility were made • The controller was slightly modified to be used on the compressor • The controller was implemented as a throttle control and a bleed valve control • In this case also the controller was able to reject and suppress the stall
Modeling of the Precursor Waves • Gain better insight into the physics of the precursor waves and model them • Plot amplitudes of surge and precursor waves versus throttle opening for the centrifugal compressor similar to the plots of rotating stall amplitude versus throttle opening in axial compressors
Future Research - Centrifugal Compressor • Make the plots for different compressor speeds to investigate the influence of RPM • Find a model for the precursor waves and investigate how general it is and if it can be cascaded with the Moore-Greitzer model to better capture the dynamics of compressors
Future Research - Centrifugal Compressor (Contd.) • Develop a model to include precursors from first principles • Develop Controllers based on precursor model
Future Research - Axial Compressor • We are in the process of purchasing a new compressor and we are going to replace the hardware and software used for data acquisition and for control • We will also analyze experimental data from the axial facility of NASA Lewis • The experimental data will be used to investigate the existence and properties of the precursor waves