Numerical and Experimental Study of the Performance Effects of Varying Vaneless Space and Vane Solidity in Radial Inflow Turbine Stators.

An extensive experimental program has been carried out on a 135?mm tip diameter radial turbine using a variety of stator designs, in order to facilitate direct performance comparisons of varying stator vane solidity and the effect of varying the vaneless space. A baseline vaned stator was designed using commercial blade design software, having 15 vanes and a vane trailing edge to rotor leading edge radius ratio (Rte/rle) of 1.13. Two additional series of stator vanes were designed and manufactured; one series having varying vane numbers of 12, 18, 24, and 30, and a further series with Rte/rle ratios of 1.05, 1.175, 1.20, and 1.25. As part of the design process a series of CFD simulations were carried out in order to guide design iterations towards achieving a matched flow capacity for each stator. In this way the variations in the measured stage efficiency could be attributed to the stator passages only, thus allowing direct comparisons to be made. Interstage measurements were taken to capture the static pressure distribution at the rotor inlet and these measurements were then used to validate subsequent numerical models. The overall losses for different stators have been quantified and the variations in the measured and computed efficiency were used to recommend optimum values of vane solidity and Rte/rle.

Structural testing and numerical simulation of a 34 m composite wind turbine blade

A full-scale 34 m composite wind turbine blade was tested to failure under flap-wise loading. Local displacement measurement equipment was developed and displacements were recorded throughout the loading history.

Ovalization of the load carrying box girder was measured in the full-scale test and simulated in non-linear FE-calculations. The nonlinear Brazier effect is characterized by a crushing pressure which causes the ovalization. To capture this effect, non-linear FE-analyses at different scales were employed. A global non-linear FE-model of the entire blade was prepared and the boundaries to a more detailed sub-model were extracted. The FE-model was calibrated based on full-scale test measurements.

Local displacement measurements helped identify the location of failure initiation which lead to catastrophic failure. Comparisons between measurements and FE-simulations showed that delamination of the outer skin was the initial failure mechanism followed by delamnination buckling which then led to collapse.