SATISH DHAWAN, India (ISRO PR) — In the quest to reduce the cost of access to space and to extend the frontiers of space exploration, ISRO has ventured into Reusable Launch Vehicle (RLV) and Re-entry missions, Air-breathing propulsion technology demonstration and Interplanetary missions. These missions encounter design criticalities at Hypersonic Mach number regime and need rigorous aero-thermodynamic characterisation at these Mach numbers.
In order to cater to the above need, Industrial type Hypersonic Wind Tunnel and Shock Tunnel have been established at Vikram Sarabhai Space Centre (VSSC).
The first phase of the facility, commissioned in 2012, with Mach 6 system and Shock Tunnel, has been extensively utilised and tests are being carried out for the current programs of ISRO.
The second phase of Hypersonic Wind tunnel consists of the realisation of Mach 8, 10 and 12 nozzles, Heater-II system, Hot Shut-off Valves, Cooling system and associated subsystems. Realisation of these systems involved intricate design and analysis, high precision machining, heavy engineering hardware realisation, fabrication of high temperature performance materials, high temperature and high pressure valves realisation, development of state of the art Cored Bricks as heat storage media, realisation of massive 15-5 PH forgings and high temperature heating modules. Integration of these systems was carried out meticulously, performance assessment was made and trial runs were conducted to calibrate and validate the tunnel systems.
With capability up to Mach 12 operation, Hypersonic Wind Tunnel is the third largest in the world in terms of hypersonic flow simulation capability over a wide spectrum. The tunnel has the capability to simulate flow field conditions at Mach 6, 8, 10 and 12 of nominal nozzle exit diameter of 1 metre with Reynolds number ranging from 1 to 80 million per metre. The tunnel is pressure-vacuum driven with high pressure storage system of 300 bar and vacuum system of 10-2 mbar capacity. Regenerative storage heater system is used to preheat the compressed air up to 1550 K before it is expanded through the nozzle to Hypersonic Mach number. The state-of-the-art technology is used for data acquisition and control of the tunnel system. Programmable Logic Controller (PLC) based system works on Dual redundant Hot Standby concept and monitors more than 100 input parameters and controls more than 60 events. The shock tunnel uses combustion driver and has the capability to simulate free stream velocities up to 4.5 km/s and a maximum Reynolds number of 3.3 million per metre.
The realisation of the above facilities paved the way for the indigenous development of technologies, in the area of Cored Bricks, Hot Shut off Valves and massive 15-5 PH forgings. Hot Shut-off Valves, the most critical valve in the tunnel circuit with simultaneous application of high pressure and high temperature of 110 bar and 1550 K respectively, have been indigenously developed. High temperature Heater system demanded high purity Alumina Cored Bricks, of low dust characteristics and high temperature thermal shock resistance, as heat storage media. These were jointly developed by ISRO and Indian industries. Massive 15-5 PH forgings with integral flanges are realised for the high pressure shock tubes designed to withstand 1000 bar and associated fatigue cycles.
The major systems of the tunnel are designed to meet the requirement of five blow downs per day. It consists of 500 valves, 2 km pipelines, 40 numbers of electric motors and 35 fluid pumps. These facilities have been indigenously designed, developed and made with the support of Indian Industries.
This Integrated Hypersonic Wind Tunnels facility has been commissioned by Chairman, ISRO / Secretary, DOS, recently during March 2017. The entire complex, consisting one metre Hypersonic Wind Tunnel, one metre Shock Tunnel and Plasma Tunnel was named as “Satish Dhawan Wind Tunnel Complex” as a tribute to Prof. Satish Dhawan, who has made very significant contributions in the field of wind tunnels and aerodynamics.