Astrophysique et technologie aérospatiale

Efficient propulsion development is an area of major interest in space industry. Chemical propulsion-oriented rockets and space systems are well known to encounter acoustic instabilities. The modified heat fluxes, owing to wall temperature, reaction rates and non-linear heat transfer are observed. The thermoacoustic instabilities significantly result in reduced combustion efficiency leading to uncontrolled rocket engine performance, serious hazards to systems, assisted testing facilities, enormous loss of resources and every year substantial amount of money is being spent to prevent them. Appreciable work had been carried out in the past leading to a progressive stand however, the complexity of the problem has prevented a comprehensive solution. Present work attempts to fundamentally understand the mechanisms governing the thermoacoustic combustion in rocket engines using a simplified experimental setup comprising of a butane cylinder and an impinging acoustic source. The RL-10 engine generates a noise of 180 Db at its base. Systematic studies are carried out for varying fuel flow rates, acoustic levels and observations are made on the flames. The work is expected to yield a good physical insight into the development of acoustic devices that could effectively enhance combustion efficiency leading to safer missions and better fire safety.

Dias, Adalberto da Costa, presented a type of somnambulism, which only manifested during his adolescence, causing him to be stuck facing the wall while he slept, because there, for all purposes, there was a door. Adalberto, throughout his life, has always been concerned with interpreting the explanation for this unusual situation. Now, nearing 75-years-old, Adalberto finally interpreted that trance state, which afflicted him in youth. There interpretation is as follows: The wall did represent an insurmountable obstacle originated in poverty and in lack of opportunity to have a good and satisfactory scientific education, especially in physics and mathematics. Despite this tremendous obstacle in his life, Adalberto is aware that he must do what must be done so that his work reaches the highest scientific level. Thinking in this way, Adalberto uses in this paper his acquired cosmo-reach in what he is stronger, which is his power to interpret universe’s secrets. Adalberto acts like a hummingbird, which carry in his beak a drop of water to spread in the forest that is on fire. He’s just doing his part.