Hypersonic vehicles experience extreme thermal loads generated by the dissipation of the vehicle's kinetic and potential energy. Thermal protection system (TPS) employed in such vehicles is designed to protect the vehicle from thermal loading by regulating this energy dissipation. Controlled energy dissipation is essential. This paper outlines the implementation of the high-temperature heat flux sensor (HTHFS), which was designed to meet the aforementioned requirements.
Hypersonic transport vehicles make use of Thermal protection systems to protect the vehicle from thermal loading by regulating any form of energy dissipation through it. During the journey, there takes place a drastic change in the heating parameters with interdependent soaring surface temperatures. Hence, what is required of the vehicles is a light in weight but efficient Thermal protection system that prevents the heat transmission into central fuselage. Gas convection, solid conduction and gas conduction are the heat transmission ways in insulation. Various thermal guard systems are dependent on several distinct methods to reduce heat transfers such as vacuum singles and micro porous insulations.
Thermal protection systems are dependent on a variety of phenomena to diminish the heat transfers, like inert gas filled shingles, micro porous insulations, vacuum shingles, and multiwall structures, are mentioned. It is verified that micro porous and several wall insulations are resourceful, light in weight and dependable TPSs for not so distant future hypersonic transportation systems. It is well noted that multiwall and micro porous insulations are light in weight, better in performance and most reliable thermal protection systems for hypersonic Thermal Protection Systems.
The use of Heat flux temperature sensors to reduce thermal heating in vehicles offer a wide variety of sensors to measure heat flux in several applications. HFP01 is one of the most widely used application in buildings and soils. Other than this, SBG is another common model used to cool fires and flames in heat flux systems in heavy vehicles. There is a coolant fluid flowing inside the system to add to the cooling effect which tends to decrease the surface temperature and flux. The coolant fluid moves across the surface and adds to the coolant effect and creates a mild temperature gradient quite near to the surface.
Latest developments in heat flux measurements have lead to the development of a versatile heat flux sensor to be used in completely extreme thermal temperatures especially in heavy vehicles. The advantage of an HTHFS is that it is capable of measuring heat flux at a temperature of 1000 degree Celsius along with measuring thermal surface temperature. Precisely, heat flux measurement is a tedious process and needs very specific designing and implementation of calibration systems and sensors. This will ensure complete accuracy in heat flux measurements. A differential temperature sensor is used to directly measure the heat flux. A type of sensor known as thermopile is used to measure differential temperature with a series of thermocouples fitted across a thermal resistance. These days’ High temperature heat flux sensors (HTHFS) are used in a calibrated form with uncooled differential heat flux sensors at high temperatures. These sensors come with an upper limit temperature of 1000 degree Celsius.
References:
Pullins A. C. (2012). In situ high temperature heat flux sensor calibration. 4 November 2012. Retrieved from http://www.vsgc.odu.edu/src/Conf2010/Grad%20Papers/Pullins_VSGC_2010_Paper.pdf
W. Atkinson W. (2012). Development of advanced high temperature heat flux sensors. 4 November 2012. Retrieved from http://www.amazon.com/Development-advanced-high-temperature-sensors-SuDoc/dp/B000103PBK
E. Diller T. (2012). Digital library and archives. 4 November 2012. Retrieved from http://scholar.lib.vt.edu/theses/available/etd-05182011-124709/
D. Wrbanek J. (2012). Thin film physical sensor instrumentation research and development at NASA glenn research center. 4 November 2012. Retrieved from http://www.grc.nasa.gov/WWW/sensors/PhySen/docs/ISA06_P023_Slides.pdf
A. Pillins C. (2012). Design, calibration and implementation of a high temperature heat flux sensor for hypersonic research. 4 November 2012. Retrieved from http://www.vsgc.odu.edu/src/Conf09/Grad%20Papers/Pullins_Paper.pdf
