PCA will be manning Booth #716 at the ASME Turbo Expo in Montreal, June 15th to 19th 2015. Chris Robinson, Graham Cox, Mick Casey, Hamid Hazby and Jason Wu will be attending the conference and will be pleased to welcome visitors to the booth. Dr Hazby and Dr Wu will present the following papers:
EFFECTS OF BLADE DEFORMATION ON THE PERFORMANCE OF A HIGH FLOW COEFFICIENT MIXED FLOW IMPELLER
HR Hazby, IH Woods, MV Casey, R Numakura and H Tamaki
The effects of blade deformation under running conditions on the performance of a highly loaded transonic mixed flow impeller were investigated. Two impellers were manufactured, one using the "running" blade profiles as designed and one using the converted "unrunning" or "cold" geometry. Both impellers were tested experimentally and investigated numerically.
The test data taken with smooth casing showed that at maximum speed, the isentropic efficiency and pressure ratio of the running geometry was higher than the unrunning geometry by about 0.4% and 1.4%, respectively. However, the difference in performance diminished in the presence of recirculating casing treatment. Numerical calculations suggested that the differences at high speeds were mainly due to the variation in the impeller tip clearance. The calculations using deformed blade profiles under centrifugal load only, predicted performance differences which were about twice as high as the measured values. However, closer predictions were obtained when the effects of pressure loads on blade deformation were included using closely coupled fluid-structural analyses.
TRANSIENT FLOW CHARACTERISTICSOF CONTRA-AND CO-ROTATING SWIRLER ARRANGEMENTS OF AN INDUSTRIAL COMBUSTOR
X Wu, ER Norster and Gang Xie
Many lean-burn combustors are prone to high levels of pressure oscillations resulting in early structural failure. These oscillations have their origins with the natural acoustic characteristics of the combustor flow/geometry and amplification and excitations factors associated with well-mixed flames. The coincidence of the frequency of these excitations with the mechanical vibration modes of the combustor may result in resonance and high cycle fatigue failure. Often with high levels of pressure oscillations the fuel system itself can become coupled driving the dynamics to higher levels. Thus detailed acoustic and mechanical vibration analysis of the combustor becomes important. This paper describes the numerically predicted transient flow characteristics of two configurations of DLN combustor double swirler in contra- and co-rotating arrangements with the sole difference being in the orientation of rotation of the inner nozzle airflow. Although much useful information has been obtained from the previous steady-state analysis, there remain many unresolved issues such as discrepancies of vortex breakdown and acoustic instabilities, which is also important for a final design selection. The transient analysis was performed for each configuration to compare flow instability and acoustic characteristics where the model includes the inlet air annulus, double swirler, main reaction zone and dilution duct. The studies indicate that there is a significant discrepancy in flow structures when the vortex breaks down between the two configurations. And there exists a strong interaction for the remaining swirl with the dilution jets, resulting in the hot core penetrating far downstream inside the transient duct in the co-rotating case. An FFT analysis indicates a significant discrepancy on main low acoustic frequencies and the magnitudes of oscillatory pressure.