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On the occasion of the 100th anniversary of M. A. Lavrent'ev, it seems pertinent to summarize the longterm work on the physical foundations, design, and manufacturing of sources of high-pressure gases for hypersonic wind tunnels in the pages of a journal founded with the immediate participation from M. A. Lavrent'ev. This direction of experimental aerodynamics received invaluable support of M. A. Lavrent'ev in early 1970s, without which the scientific ideas would not, probably, be put into practice.The idea of using high (up to 20,000 atm) pressures of a gas in the plenum chamber in an aerodynamic experiment was first put forward in the late 1960s by M. A. Plotnikov [1] who worked at that time in Research Institute-1 in the group of Prof. E. I. Shchetinkov, one of the founders and proponents for using supersonic combustion in air-breathing engines of hypersonic flying vehicles (HFV) for Mach numbers from 8 to 20 [2]. At the same time, the papers of Soviet and American scientists posed the question of the necessity of developing of a reentry HFV with an aircraft-type take-off and landing, capable of taking payloads to the orbit of an Earth's satellite and back. It is expected that, with the use of these vehicles, the cost of putting payloads to orbit, which is the key economic factor of using spacecraft systems in practical activity outside of the military field, will decrease by 5 to 8 times. One of the main obstacles for the use of such systems is the absence of knowledge on the complex of fundamental phenomena that accompany and ensure the HFV flight. The existing hypersonic aerodynamic facilities do not allow one to create conditions necessary for testing the corresponding HFV models [4]. This is especially true for reproduction of Reynolds numbers and ensuring test-gas purity and run time.At the end of the 1960s, M. A. Plotnikov and his colleagues developed tables of thermodynamic functions of nitrogen [1] from which it followed that the transition to the pressure region up to 10,000-20,000 atm leads to an additional contribution to the gas enthalpy equivalent to a temperature increase by approximately 1000 K per each 10,000 atm. On the one hand, this offered a possibility of increasing the Lavrent'ev Institute

The prospects for developing astronautics, the utilization of space stations and platforms, and the development of systems for communication, navigation, and environmental observations require development of a new generation of transport systems which can substantially lower the cost of putting cargo and people into orbit around the Earth and other planets. Returning dangerous and derelict structures from space will become an even more urgent problem, as they become more noticeable; in the future they can become a serious ecological problem.Efforts to solve these problems have recently led to the planning of several space transport systems, including [ Realizing these plans depends to a large degree on successfully solving the following problems: airframe aerothermodynamics, the gas dynamics of mixing and heating in the jet engines, and design optimization of the airframe, the air intakes, and the nozzle assembly.These transport system concepts have several problems in common, including: --external aerodynamics of shock encounters with the laminar and turbulent boundary layers; --aerodynamic heating, ablation, and erosion of spacecraft surfaces; --internal gas dynamics in the engines (flow interactions in air intakes and combustion chambers, mixing and compression of the fuel under prolonged hypersonic conditions, and completeness of chemical reactions); -modeling non-ideal gas effects related to molecular dissociation and recombination and to excitation of vibrational degrees of freedom at high static temperatures; and --catalytic interaction of aircraft surfaces and the resultant local structural heating. At least some of these plans envision a highly efficient hypersonic aircraft that uses atmospheric oxygen as the oxidizer during the jet boost phase and burns up the fuel at high hypersonic velocities (hypersonic-combustion ramjet).Current studies of the physical processes that occur during hypersonic combustion in a jet engine are woefully inadequate. One reason for this is that the wind tunnels and high-enthalpy facilities used for this research do not totally model the Reynolds number, often contaminate the airflow, and do not provide steady-state conditions for the times necessary to establish equilibrium in modeling the combustion.At the same time, numerical methods of solving these are still limited, and their development is retarded in many cases by the lack of reliable experimental data required to verify the models and methods which are selected and developed. Therefore, in spite of the constant progress in numerical algorithms and in computer capabilities, experimental research remains the basis for solving these problems and for developing numerical methods.Flight tests are extremely expensive and do not provide enough information, not to mention the fact that the range of the results are related only to currently existing systems, not future ones. Obviously, they can be useful and effective only in the final stage of design testing. Therefore construction of ground facilities capable of handling mo...

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