Executive Summary : | The present project aims to investigate unsteady aerodynamics that arises at part load condition in LP turbine. The part load condition which causes upstream separated flow near the tip of the blade is produced with the help of step placed at upstream of the blade. For the LP turbine at low volume flow after a certain limit, energy is returned to working fluid rather than extracting energy. This is known as ventilation which can cause non-synchronous aerodynamic excitation. This excitation can be a major risk to the mechanical integrity of last stage moving blade in LP turbine. The last stage blade aspect ratio is high and unshrouded tip section. So blade vibration is a major concern. Also due to the adverse pressure gradient, the flow near the tip of the long turbine blade gets separated. Due to low volume flow in LP turbine, the steam can no longer pass through close to the root, and it is redirected towards the tip and as a result, a separation zone is developed behind the rotor blade. The large-scale separation pattern may cause a stall situation similar to a compressor. This will lead to strong coupling of flow and turbine blade structure and vibration.
The proposed work is to investigate the unsteady aerodynamic response of a rotor blade under incoming separated flow condition. Preliminary work will be carried out with a three dimensional blades in a simulated condition in a wind tunnel. The unsteady pressure fluctuation will be measured using pressure transducers mounted on the blade surface under different incoming separated flow condition. Also, the unsteady flow field information will be captured using Particle image velocimetry, hotwire anemometer and flow visualization technique. The different blade vibration mode will be captured under part load condition. Effort will be made to control the flutter using feedback control mechanism. |
Co-PI: | Dr. Arup Kumar Das Indian Institute Of Technology Roorkee, Uttarakhand,Roorkee - Haridwar Highway, Roorkee,Uttarakhand,Haridwar-247667, Dr. Pathak Pushparaj Mani Indian Institute Of Technology Roorkee, Uttarakhand,Roorkee - Haridwar Highway, Roorkee,Uttarakhand,Haridwar-247667 |