2020 Volume 11 Issue 2 Pages 9-16
Pneumatic probes are commonly used to determine the flow vector as well as the thermodynamic state of the fluid in turbomachinery applications. The conventional method to measure a flow passage velocity or pressure field is to move the probe to discrete positions and to hold a certain settling time before valid data can be recorded. This study presents a measurement methodology leading to a reduction in the required measurement duration of up to 70-90%, depending on the level of flow field resolution. The approach is based on the concept of continuously traversing probes as introduced by Gomes et al. [1]. However, the system model is changed by reducing the transfer function to a single PT1-behavior. While the experiments conducted by Gomes et al. [1] were limited to only linear cascade measurements, the method used here is extended to turbomachinery applications with highly complex flow structures. The continuous traverse measurements are validated through a comparison with conventional discrete measurements that include characteristic settling time. For this purpose, tests have been performed in an axial diffuser test rig operated with air and a low pressure steam turbine. The results obtained with the new approach show a good match, thus proving the viability of the proposed method for turbomachinery applications. For future tests, a significant reduction in measurement time and cost can be achieved.
