Experimental Investigations of Hydrocarbon Fueled Scramjet Combustor by Employing High Temperature Materials for the Construction of Fuel Injection Struts

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Author(s) C. Chandrasekhar | V. Ramanujachari | T.Kishen Kumar Reddy
Pages 671-678
Volume 1
Issue 12
Date December, 2012
Keywords Hypersonic, Scramjet, Strut, Niobium C-103, W-Ni-Fe, Nimonic C-263
Abstract

For the Hypersonic Technology Demonstrator Vehicle (HSTDV) programme half-width strut based scramjet combustor has been designed, developed and tested for the short durations (5 s) as well as for the long durations (20 s) using various materials for the construction of fuel injection struts. Extensive experimental investigations have been carried out to identify suitable material for the long duration (20 s) tests. Niobium C-103 alloy and W-Ni-Fe alloy materials have been used for the construction of fuel injection struts and they have been employed in two different tests. In the first test struts made of Niobium alloy is used and in the second test struts made of W-Ni-Fe alloy is used. It is inferred from the results of the static tests for the 20 s test duration that the leading edges of the struts are eroding due to high thermal load, shear force and oxidizing environments in the five-strut scramjet combustor configuration. The failure of the struts is noticed in the Stage-II injection of the scramjet combustor. The thermo-structural failure of the stage-II fuel injection struts in the scramjet combustor in both the tests has detrimental effect on the performance of the combustor. In the case of Niobium C-103 alloy struts, erosion of the leading edges is found to be severe compared to W-Ni-Fe alloy struts. Hence, the total pressure loss in the former is found to be more compared to the latter. In the first test (Niobium struts used) the flow separation is occurring earlier compared to the second test (W-Ni-Fe struts employed). This is indicative of the onset of the severe leading edges erosion of Niobium C-103 alloy struts compared to W-Ni-Fe alloy struts resulted in more skin friction drag and hence the flow separation at a shorter length. Struts made of W-Ni-Fe alloy seem to be promising candidate material compared to Niobium C-103 alloy.
Subsequent tests carried out by employing struts made of W-Ni-Fe alloy divulged that the powder metallurgy route to realise the W-Ni-Fe alloy plate is unable to deliver/impart consistent mechanical properties in all the directions of the plate i.e., anisotropy is prevailing. On this front, it is found that the material developed at this juncture is found to be unsuitable for the scramjet application. To circumvent such scenario two strategies have been proposed for the realization of fuel injection elements.

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