Evaluation of Kerosene Fuelled Scramjet Combustor using a Combination of Cooled and Uncooled Struts

C. Chandrasekhar; V. Ramanujachari; T. Kishen Kumar Reddy

doi:10.14429/dsj.64.2733

C. Chandrasekhar Defence Research & Development Laboratory, Hyderabad
V. Ramanujachari Defence Research & Development Laboratory, Hyderabad
T. Kishen Kumar Reddy Jawaharlal Nehru Technological University, Hyderabad

DOI: https://doi.org/10.14429/dsj.64.2733

Keywords: Scramjet, cooled strut, nimonic C-263 alloy, ejector system, adverse pressure gradient

Abstract

The scramjet combustor a vital component of scramjet engine has been designed by employing fuel injection struts. Several experimental studies have been carried out to evaluate the propulsive performance and structural integrity of the in-stream fuel injection struts in the connect-pipe test facility. As the mission objective of hypersonic demonstrator is to flight test the scramjet engine for 20 s duration, in-stream fuel injection struts which are designed as heat sink devices encounter hostile flow field conditions especially in terms of high thermal and high convective loads in the scramjet combustor. To circumvent these adverse conditions, materials like Niobium C-103 and W-Ni-Fe alloys have been used for the construction of struts and a number of tests have been carried out to evaluate the survivability of the in-stream fuel injection struts in the scramjet combustor. The results thus obtained show that the erosion of leading edges of the Stage-II fuel injection struts in the initial phase and subsequently puncturing of the fuel injection manifold after 10-12 s of the test are noticed, while the other stages of the struts are found to be intact. This deteriorating leading edges of Stage-II struts with respect to time, affect the overall propulsive performance of the combustor. To mitigate this situation, Stage-II struts have been designed as cooled structure and other Stages of struts are designed as un-cooled structure. Material of construction of struts used is Nimonic C-263 alloy. This paper highlights the results of the static test of the scramjet combustor, which has been carried out at a combustor entry Mach number of 2.0, total temperature of 2000 K, with an overall kerosene fuel equivalence ratio of 1.0 and for the supersonic combustion duration of 20 s. Low back pressure has been created at the exit of the scramjet combustor using ejector system to avoid flow separation.Visual inspection of the fuel injection struts after the test revealed that all the Struts are found to be thermo-structurally safe in the combustor environment except for minor erosion of the leading edges of the struts. Stage-II struts made of two-passage cooled configuration are found to be thermo-structurally safe. Although other stages of struts used in the test are of un-cooled configuration, they too are found to be safe and intact. This demonstrates the fact that they experience thermally benign flow conditions compared to Stage-II struts in the scramjet combustor.

Defence Science Journal, 2014, 64(1), DOI:http://dx.doi.org/10.14429/dsj.64.2733

Author Biographies

C. Chandrasekhar, Defence Research & Development Laboratory, Hyderabad

Mr C. Chandrasekhar obtained his BE (Mechanical Engineering) from Visvesvaraya Regional College of Engineering (now VNIT), Nagpur in 1991 and ME (Mechanical Engg.-Guided Missiles) in 1997 from Institute of Armament Technology (now DIAT), Pune. Presently working as a Scientist at Defence Research & Development Laboratory (DRDL), Hyderabad. His research interests are in field of scramjet propulsion technology.

V. Ramanujachari, Defence Research & Development Laboratory, Hyderabad

Dr V. Ramanujachari started his career in DRDL, Hyderabad as Scientist ‘B’ in 1982 and worked on the Airbreathing Propulsion system for AKASH missile. Later, he taught at the Institute of Armament Technology, Pune. He was the Project Director of HSTDV project at DRDL, Hyderabad during 2009-2012. Presently he is holding the position of Director, Research & Innovation Centre, IIT, Madras Research Park, Chennai. His interests are in the fields of combustion and propulsion.

T. Kishen Kumar Reddy, Jawaharlal Nehru Technological University, Hyderabad

Dr T. Kishen Kumar Reddy received his BE (Mechanical Engineering) from Osmania University in 1978 and MTech (Heat Transfer and Thermal Power Engineering) from IIT, Madras in 1980. He received his MS and PhD in Thermal Fluid Sciences from Drexel University, USA in 1983 and 1987, respectively. Presently he is a Professor of Mechanical Engineering and also OSD to Vice Chancellor, Jawaharlal Nehru Technological University, Hyderabad. His areas of expertise are Thermodynamics, Fuels, Heat Transfer and CFD.