PCA will be manning Booth #715 at the ASME Turbo Expp in Dusseldorf, June 16th to 20th 2014. Chris Robinson, Mick Casey, Hamid Hazby and Jason Wu will be attending the conference and will be pleased to welcome visitors to the booth.
PCA staff are involved in a number of technical papers as lead and supporting authors:-
FLOW CHARACTERISTICS OF CONTRA- AND CO-ROTATING SWIRLER ARRANGEMENTS OF AN INDUSTRIAL COMBUSTOR
X Wu, ER Norster and Gang Xie
This paper describes the investigation of the flow characteristics of two double radial inflow swirlers configured for use in a gas turbine combustor.
The only difference between the two swirlers is in the contra- and co-rotating flow of air in the inner nozzle arrangement. The isothermal vortex flow field created by the double swirlers has been examined using numerical Model 1. The model also includes a cylinder reaction zone downstream of the swirler. The comparison of flow characteristics is carried out by examination of the spatial resolution of three mean velocity components. The contra- and co-rotating configurations show some discrepancy in terms of total loss factor and mass split ratio between the two swirlers. The comparison of flow fields also indicate that there is almost no remaining swirl further downstream in the contra-rotating configuration, while a significant amount of remaining swirl exists for the co-rotating option. The development of Model 1 to include a typical dilution zone and transition duct leads to numerical Model 2, which was used to investigate the impact on downstream mixing with the dilution air and the emerging temperature distribution at the transition duct exit. Comparing the temperature field for both configurations, the dilution effectiveness increases significantly with dilution jet penetration depth and reduces with spread along the circumferential direction. These effects lead to the central hot core persisting along the transition duct to the combustor outlet for the co-rotating option due to the combination of initial cross flow and a strong swirl, resulting in a considerable difference in the predicted outlet temperature distribution factors (OTDF) of 10.8% and 17.7% for the contra- and co-rotating arrangements, respectively.
A TRANSONIC MIXED FLOW COMPRESSOR FOR AN EXTREME DUTY
Hamid Hazby, Michael Casey, Ryusuke Numakura and Hideaki Tamaki.
This paper describes the design of a transonic mixed flow compressor stage for an extreme duty, with an extremely high flow coefficient (ϕ) of 0.25 and a high isentropic pressure rise coefficient (ø) of 0.56.
The impeller design makes use of modern aerodynamic practice from radial and transonic axial compressors, whereby the aerodynamic blade shape involved arbitrary surfaces on several spanwise sections. Some aspects of the aerodynamic optimization of the design were limited by mechanical considerations, but nevertheless the test data obtained on a prototype stage demonstrates that acceptable performance levels can be achieved at these extreme design conditions, although map width enhancement devices were needed to obtain an acceptable operating range. The test data is compared with CFD predictions to demonstrate the validity of the design methods used.
EFFECT OF A RECIRCULATION DEVICE ON THE PERFORMANCE OF TRANSONIC MIXED FLOW COMPRESSORS
Ryusuke Numakura, Hideaki Tamaki, Hamid Hazby and Michael Casey.
Two transonic mixed flow compressors with an extremely high flow coefficient of ϕ = 0.25 and pressure ratios of 2.5 and 2.65 have been designed and tested. CFD simulations indicated that both impellers operate with a suction surface relative Mach number of above 1.5 at their design conditions. Both compressors achieved a narrow stable operating range when tested without recirculation devices. The effects of two different recirculation devices on the compressor performance maps were investigated both experimentally and numerically. . The first type is a widely used recirculation device which consists of an upstream slot, bleed slot and an annular cavity which connects both slots. The other has vanes installed in the cavity which were designed to provide a recirculation flow with negative swirl at the impeller inlet. Measurement data demonstrated the effect of the recirculation devices on increasing the range of these two transonic mixed flow compressors and showed the superiority of the recirculation device with vanes. The effects of the recirculation devices on the impeller flow field at near surge conditions are studied.
THE MATCHING OF A VANED DIFFUSER WITH A RADIAL COMPRESSOR IMPELLER AND ITS EFFECT ON THE STAGE PERFORMANCE
Michael Casey and Daniel Rusch.
The matching of a vaned diffuser with a centrifugal impeller is examined with a one-dimensional (1D) analysis combined with extensive experimental data. A matching equation is derived to define the required throat area of the diffuser relative to the throat area of the impeller at different design speeds and validated by comparison with a wide range of compressor designs. The matching equation is then used to give design guidelines for the throat area of vaned diffusers operating with impellers at different tip-speed Mach numbers.
An analysis of test data for a range of high pressure ratio turbocharger compressor stages is presented in which different matching between the diffuser and the impeller has been experimentally examined. The test data includes different impellers with different diffuser throat areas over a wide range of speeds. It is shown that the changes in performance with speed and diffuser throat area can be explained on the basis of the tip-speed Mach number which causes both the diffuser and impeller to choke at the same mass flow. Based on this understanding, a radial compressor map prediction method is extended to include this parameter, so that more accurate maps for matched and mismatched vaned diffusers can be predicted.