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30 August 2004 Gaso-dynamic counterbalancer for pneumatically driven expander in rotary split Stirling cryocooler
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Numerous military thermal imagers operating under hostile environmental conditions rely on tactical rotary split Stirling cryocoolers, the pneumatically driven expanders of which are known to be the source of considerable vibration export. The cold tip temperature in such a cooler is typically stabilized by controlling the driving frequency in accordance with thermal loading and ambient temperature, leading to a frequency-swept harmonic vibration export into the optomechanical structure of the thermal imager. The active vibration cancellation systems are basically capable of suppressing such vibration, but are still quite bulky, complicated and expensive. In this paper, the authors report on the recent efforts towards developing a low cost vibration counterbalancer for a pneumatically driven expander in a rotary cryogenic cooler. In this approach, the flexurally suspended auxiliary mass - counterbalancer - is arranged to oscillate coaxially with the expander’s displacer and is driven pneumatically by the pulses of the working fluid produced by the compressor. Based on the results of analytical modeling and Sage optimization, the counterbalancer was designed and manufactured as an integral part of such an expander. The full-scale experimentation has shown essential cancellation of vibration export within the working frequency range from 30 to 60Hz without noticeable effect on cryocooler performance.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sergey V. Riabzev, Alexander M. Veprik, Nachman Pundak, Uri Pratt, and Herman Vilenchik "Gaso-dynamic counterbalancer for pneumatically driven expander in rotary split Stirling cryocooler", Proc. SPIE 5406, Infrared Technology and Applications XXX, (30 August 2004);

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