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T-noise, the fluctuating part of local temperatures in a thermohydraulic system, is measured as the difference of the actual temperature from the mean or static temperature. It is a random quantity and contains useful information about the thermohydraulic system and the process involved. Measurement techniques used in the experimental applications are discussed: differential T-probes, differential response time probes, multiple probes or T-signals with HP-filtering. The electronic hardware plays an important part in getting reliable T-noise data. The two application examples of T-noise measurements in thermohydraulic investigations are studied. Signal analysis of T-noise measurements in the coolant outlet flow allows the detection of anomalies in a heater rod bundle, e.g. flow blockages, which provides an early failure detection method for nuclear fuel rod bundles. By use of correlation techniques, T-noise data can provide flow velocity measurements, for instance in thermohydraulic experiments with two-phase flows. This method is presently in use at the LOBI test facility for experiments in the field of water reactor safety research, where a number of measurement problems were faced and special data handling techniques developed to get reliable flow velocity measurements from the T-noise data.

Additional information

Authors: OHLMER E, JRC Ispra (IT);CHENNEAUX F, JRC Ispra (IT)
Bibliographic Reference: Paper presented: 3rd Workshop on Differential Temperature Measurements, Budapest (HU), Sept. 6-7, 1989
Availability: Available from (1) as Paper EN 34890 ORA
Record Number: 199010800 / Last updated on: 1994-12-01
Original language: en
Available languages: en