Effects of Thermal Effusivity in Nanocrystalline Porous Silicon on Long-Term Operation of Thermally Induced Ultrasonic Emission

The operational issues of a small turbojet engine MPM – 20 are discussed. The engine was created by modifying the Soviet turbostarter TS – 20B/21 designed for short-term operation. It is necessary to make structural modifications that allow for the long-term operational premise of the engine. For this purpose, several analyses were focused on the thermally stressed parts. The first, a material analysis carried out on the outer casing of the combustion chamber and on the combustor liner reveals information about the mechanical properties of these structural nodes. It was necessary since there is no documentation of the engine with this information. Another analysis of the infrared emission spectra is important for monitoring operational conditions, especially from the temperature point of view. Subsequent stress analysis of the casing is based on results from previous analyses. It was used to observe the behaviour of the casing as operational conditions changed. This revealed a dangerous increase of thermally induced stress levels as temperature increased up to 150°C. Various structural modifications can be made in the future with these results, such as an application of a protective coating on the casing and combustor liner of the engine.

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Generalized Theory of Thermo-Acoustic Emission from Nanocrystalline Porous Silicon

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.472.734 ◽

2014 ◽

Vol 472 ◽

pp. 734-738 ◽

Cited By ~ 1

Author(s):

Yan Dong Wang ◽

Han Ping Hu ◽

Dong Dong Wang

Keyword(s):

Acoustic Emission ◽

Porous Silicon ◽

General Expression ◽

Multilayer Structure ◽

Thermal Contact ◽

Experimental Results ◽

Nanoporous Silicon ◽

Thermally Induced ◽

Ultrasonic Emission

In this work, a general expression of the thermo-acoustic (TA) emission from nanocrystalline porous silicon (nc-PS) is derived by using a fully thermally-mechanically coupled multilayer TA model. This expression takes thermal, mechanical, and geometry properties of every layer in a multilayer structure, as well as the thermal contact resistances between layers into consideration and hence agrees well with the experimental results. Therefore, many fundamental problems in thermally induced ultrasonic emission from nanoporous silicon can be studied.

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