Abstract
In order to overcome the drag at hypersonic speed, hypersonic flight vehicles require a high level of integration between the airframe and the propulsion system. Propulsion system based on scramjet engine needs a close interaction between its aerodynamics and stability. Hypersonic vehicle nozzles which are responsible for generating most of the thrust generally are fused with the vehicle afterbody influencing the thrust efficiency and vehicle stability. Single expansion ramp nozzles (SERN) produce enough thrust necessary to hypersonic flight and are the subject of analysis of this work. Flow expansion within a nozzle is naturally 3D phenomena; however, the use of side walls controls the expansion approximating it to a 2D flow confined. An experimental study of nozzle performance traditionally uses the stagnation conditions and the area ratio of the diverging section of the tunnel for approaching the combustor exit conditions. In this work, a complete hypersonic vehicle based on scramjet propulsion is installed in the test section of a hypersonic shock tunnel. Therefore, the SERN inlet conditions are the real conditions from the combustor exit. The performance of a SERN is evaluated experimentally under real conditions obtained from the combustor exit. To quantify the SERN performance parameters such as thrust, axial thrust coefficient Cfx and lift L are investigated and evaluated. The generated thrust was determined from both static and pitot pressure measurements considering the installation of side walls to approximate 2D flow. Measurements obtained by a rake show that the flow at the nozzle exit is not symmetric. Pitot and pressure measurements inside the combustion chamber show nonuniform flow condition as expected due to side wall compression and boundary layer. The total axial thrust for the nozzle obtained with the side wall is slightly higher than without it. Static pressure measurements at the centerline of the nozzle show that the residence time of the flow in the expansion section is short enough and the flow of the central region of the nozzle is not altered by the lateral expansion when nozzle configuration does not include side walls.
Highlights
Hypersonic air-breathing propulsion systems based on scramjet engines is one potential alternative to rocket propulsion systems
The pressure distribution at the nozzle exit is measured by the pitot rake, while the static pressure on the nozzle centerline is measured by pressure transducers
The pressure distribution of the Single expansion ramp nozzles (SERN) nozzle is symmetric in the width direction [29]; for the results obtained in Figure 11, the difference of the pressure distribution with respect to the central line can be attributed to interferences in the compression section geometry or in the combustion chamber geometry of the experimental model
Summary
Hypersonic air-breathing propulsion systems based on scramjet engines is one potential alternative to rocket propulsion systems. Rocket propulsion requires additional systems for storage and handling the oxidant for combustion limiting the overall payload. For hypersonic air-breathing propulsion systems, the oxidant is obtained from the International Journal of Aerospace Engineering atmosphere allowing reducing weight and allowing higher payloads. Nagamatsu at the Institute for Advanced Studies (IEAv), Brazil, is investigating and developing a hypersonic vehicle with an airframe-integrated scramjet engine as an option of space access in the near future [1]. The main objective is to design, develop, and manufacture a technological demonstrator 14-X based on waverider concept to obtain lift at higher altitudes and on scramjet technology to generate enough thrust for hypersonic flight through the atmosphere at 30 km altitude and Mach number 10
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