Speaker
Description
Nowadays, testing remains a key milestone in the verification of the thermal control subsystem of any space project. TVAC tests have two main goals: the verification of the correct operation and survival of the system under thermal environmental conditions representative of the orbital scenario, and the reduction of the thermal model uncertainties by means of thermal balance tests and later correlation.
Correlation based on thermal balance tests requires reaching thermal equilibrium under a series of boundary and operational conditions. As a result, tests become very long and expensive, and one risks overloading locally some regions of the system.
An alternative to traditional thermal balance tests to generate data for correlations would then become an attractive solution. Thermal characterization by means of transient tests based on oscillatory heatloads and the use of phase shift between the different locations of interest is a common practice outside of the space sector. This methodology allows the thermal engineer to perform thermal correlations of models based on periodic responses with low amplitude, and therefore avoiding over stressing, without the need to reach thermal balance, shortening the total test duration. In addition, by not relying on the amplitude of the response these tests are insensitive or have greatly reduced sensitivity to heat leakages allowing for e.g. out of vacuum testing. Furthermore, by running multiple oscillatory profiles at the same time at different frequencies and by subsequent decomposition of the response (i.e. frequency decomposition) multiple characterization tests may be performed at once.
While this approach will definitely not replace traditional TVAC tests, for some applications it may offer distinct advantages over more traditional approaches and can reduce the time needed in TVAC. This presentation displays the first numerical and experimental steps performed to consolidate a correlation methodology for space systems based on phase shift responses under oscillatory headloads.
