„Spatially resolved temperature and gas phase velocity measurements for analyzing the flow conditions in evaporating fuel“

The challenge in measuring the gas flow and temperature stratification in a heated rod bundle is the difficult accessibility of the subchannels due to the high temperatures and the used construction materials. Optical distortions caused by temperature gradients are problematic for typical optical flow measurement techniques (PIV, LDA). The aim of the TUD-ASP contribution to the measurement instrumentation is to select and qualify appropriate methods with which gas flows can be measured within rod bundle geometries under typical thermal-hydraulic conditions. For this purpose a wire mesh sensor for measuring gas temperatures and gas velocities (DE 10 2007 019 925 and DE 10 2007 019 927) is designed and constructed. In addition to solving technological problems (transducer elements, multiplexing, temperature resistance, structural design), extensive studies on application limits, uncertainties, limits of detection, cross-sensitivities, etc. are planned (also by comparison with PIV and local thermocouple measurements).For the data analysis of the integral experiments, appropriate algorithms for analysis will be developed and compared with CFD simulation results. In addition, a sensor array for measuring gas flows in the heated bundle of the integral test-facility at TUD-WKET (temperature, velocity, turbulence) will be developed. After the successful set-up of the temperature and velocity measuring grid sensor system, it is further developed for extreme operating conditions. In parallel, alternative methods for measuring the gas velocity measurement in the bundle will be looked for. The development and application of the measurement system at the integral test facility takes place in close collaboration with the partners from TUD-WKET.