After the successful operationalization of Polar Satellite Launch Vehicle and Geo Synchronous Launch Vehicle, the Indian Space Research Organisation is in the process of developing Reusable Launch Vehicle technologies to achieve low-cost access to space. Towards this programme, a winged body configuration was conceived, which can fly at subsonic, supersonic and hypersonic Mach number regime, re-enter into the earth's atmosphere and simulate the landing manoeuvre. The aerodynamic design, analysis and wind-tunnel testing, aerothermal and structural design, analysis and testing were carried out. Suitable solid motor with slow burn rate propellant was developed. Mission design, guidance and control schemes were implemented. In order to meet the above objectives, certain technologies and infrastructure were developed. The entire subsystems were integrated and a large number of flight measurements were made in the maiden successful flight of Reusable Launch Vehicle Technology Demonstrator in May 2016. The flight measurements and flight performance indicated that the design philosophy, testing schemes and approaches followed are in order, thus providing confidence to proceed to the next logical step in the development of Reusable Launch Vehicle Technologies.
This paper presents the interaction of a highly underexpanded supersonic jet of Mjet = 3.19 with hypersonic cross flow (M∞ = 6). The jet interaction flowfield was studied through wall static pressure measurement, Schlieren, and oil flow visualization. The results clearly demonstrate that flow separation is a strong function of jet pressure ratio (PR). To understand the overall flow physics, numerical simulations were also carried out. The flow features such as primary, secondary, tertiary, and quaternary vortex in separated boundary layer, horseshoe vortices, and its foot print downstream of the injection port were predicted well.
Experiments are carried out in supersonic flow past cavities (L/D = 1–3) to comprehend cavity oscillation from transverse to longitudinal mode. To characterize this, time-resolved schlieren images and unsteady pressure measurements are carried out. For L/D = 1, the cavity oscillation is in the transverse direction which is characterized by a single vortex along with low frequency oscillations. In the present studies, for the given length and depth, the L/D = 2 cavity shows both transverse and longitudinal mode of oscillations. This dual nature is ascertained through high-speed schlieren images and large rise in the fluctuating pressure. For L/D = 3, the cavity oscillation is in the longitudinal direction accompanied by low values of fluctuating pressure component and number of discrete modes/tones. Hence, it is believed that the transverse to longitudinal mode of cavity oscillation in the present studies occurs between L/D = 2 and 3. These cavities are driven by a thick shear layer where the vortex convection is found to be nonlinear. The comparison of dominant modes/tones with modified Rossiter and Handa relations indicates the necessity to develop a suitable model for transitional cavities. In-depth analyzes in terms of cross-correlation as well as wavelet transform divulge the basis that generates cavity modes/tones and mode switching phenomena, respectively.
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