Laboratory for Hypersonic and Shock wave Research
Department of Aerospace Engineering, Indian Institute of Science
Research
The Laboratory for Hypersonic and Shock Wave Research (LHSR) was started with the primary goal of carrying out research in the field of hypersonics that helps the ongoing aerospace activities in the country. Because of the complex interdisciplinary nature of the field of hypersonics it was decided to initiate research work in all the allied areas of specialization with the help of collaboration with various experts both inside the campus as well as outside institutions in India and abroad. The additional areas of specialization included physics of shock wave phenomenon, application of shock waves in biology, agriculture, wood and oil industries, High Temperature Chemical Kinetics and advanced materials research. Major contributions made in these fields are described briefly in the following sections:

Laboratory for Hypersonic and Shock Wave Research (LHSR) building

Hypersonic research provides useful aerodynamic data by measuring aerodynamic forces and surface heat transfer rates on various model configurations in hypersonic flight flow regimes, simulated in Hypersonic Shock Tunnels, for better aerodynamic design. Besides, different fundamental aspects of hypersonic flow are studied on simple as well as complex geometries that enhance our understanding for better application to real problems. Some of these are hypersonic boundary layer, shock interaction, radiating shock layer and high temperature real gas effects.

Shock waves research provides better insight in understanding the shock wave phenomenon that enhances our understanding of the fundamentals of shock wave physics. One primary aspect of research in this field is supersonic jets. A facility enabling studies into various aspects of supersonic jets has been established at LHSR. The facility consists of stagnation vessels capable of holding 6 cubic meter compressed air at 12 bar pressure, which is fed by a compressor. The air from the stagnation vessel to the experimental test rig, via steel piping, is controlled by a pressure regulator and a solenoid operated valve. The test rig is capable of great deal of flexibility. Currently studies on supersonic ejector an enclosed ducting involving a supersonic jet and a co-flow, wall jets a supersonic jet having a wall on one side and open to ambient on the other are being carried out. The facility can also be used for study of open supersonic jets, and with appropriate additions can be converted to a small scale blow-down supersonic wind tunnel. Some of the research problems studied in the facility are measurement and schlieren flow visualization of the operation of a supersonic ejector, wall pressure measurement, surface flow patterns and schlieren flow visualizations of a Mach 1.6 wall jet with and without boundary layer perturbing devices.

Flow through a supersonic ejector, showing the supersonic jet entraining a co flow, the shock structure within the supersonic jet (Mach 2.5) and the shear layers are clearly demarcated and the eventual mixed turbulent flow is also seen.

Schlieren of a wall jet (Mach 1.6) showing the interactions of the shock and expansions with a wall at the bottom and a free shear layer at the top.

One of the important aspects of our shock wave research is the development of small size devises for producing shock waves of different strengths suitable for biological and other applications. The devises include the Nonel tube capable of producing Mach 2 shock waves, Manually operated piston driven shock tube named as Reddy Tube capable of producing upto Mach 2 shock waves inside medical syringe needles of mm diameter, modified Reddy Tube for chemical kinetics studies, Micro size Reddy Tube driven light gas gun capable of firing a 4mm diameter bullet at 100 m/s speed by hand operation and more than 450 m/s speed by operating using high pressure gas.

Modifies Nonel tube for needleless drug delivery.

Medical syringe converted into piston driven shock tube by inserting a thin plastic diaphragm between the syringe and the hypodermic needle. The sharp eliptic tip of the needle is removed by grinding.

Modified Reddy tube with 4 mm diameter shock tube used for high temperature chemical kinetics studies.

Chemical Kinetics research involves study of reaction rates of different compounds. Rate constant K(T) and ignition delay of compounds which has importance in atmospheric chemistry is determined at various temperatures. These measurements can be used for understanding reaction dynamics. These are useful in combustion, explosion and detonation systems also.

Various shock wave devices finds application in Bio-sciences. Shock wave assisted preservative impregnation system has been developed to replace the existing expensive and time-consuming methods. Shock wave treatment on sandalwood has resulted in substantial reduction in sandal oil extraction time without the loss of quality of the sandal oil extracted. Bacterial cell transformation can be improved by shock waves treatment on prokaryotic cells, by which the cell membrane permeability seems to increase temporarily that results in increased transfer of naked DNA. A new micro particle delivery system has been designed, fabricated and tested using the concept of micro-blast wave loading.

For a better understanding on Shock waves please refer to the link below,

http://www.ias.ac.in/resonance/August2008/p752-767.pdf