Atomic perspectives revealing the evolution behavior of aluminum nanoparticles in energetic materials

This research focuses on theoretically and experimentally evaluating the performance of a metallized hybrid-propellant, water-breathing ramjet. The aluminum and/or magnesium particles added to a polymeric (polyester) fuel grain are hydro-reactive, using the surrounding water as an oxidizer, in addition to a source of gas. Theoretically, the metal additives significantly increase the specific impulse of the motor, and as the percentage of the hydro-reactive ingredient increases, the theoretical performance increases as well. Additionally, aluminum is more energetic than magnesium. However, it was experimentally discovered that the addition of aluminum beyond 20% resulted in a slag formation and did not increase the specific impulse. Adding 30% of magnesium was relatively favorable to aluminum due to its better reactivity, enabling the achievement of an actual specific impulse of up to 485 s at standard conditions, approximately double the performance of common solid rockets.

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Examining Metal Additives in a Marine Hybrid-Propellant, Water-Breathing Ramjet

Effect of Fast-burning Compound ACP and Catalyst on the Combustion Performance of Al/Mg-based Fuel-rich HTPB Propellants

This work presents theoretical and experimental performance studies and a general scheme of an innovative concept for propelling marine high-speed underwater vehicles, a water-breathing hybrid ram rocket. The water-augmented hybrid ram rocket enables obtaining superior performance relatively to a standard rocket and improved performance relatively to a parallel water–augmented solid ram rocket. In addition, it demonstrates improved safety and controllability due to the hybrid motor characteristics. The theoretical model incorporated data from a thermochemical program. The experimental investigation was based on static firing tests of hybrid rocket motors augmented by the addition of water during combustion. The study focused on the use of a non-water-reactive propellant combination, cured polyester as fuel and gaseous oxygen as oxidizer. Wide ranges of oxidizer-to-fuel and water-to-propellant ratios were considered. The experimental results showed a significant improvement (up to 70%) in specific impulse, relatively to a non-water-augmented hybrid rocket, in good accordance with the theoretical results. It is concluded that for standard chamber pressure of 6.9 MPa, corresponding to the ram pressure for cruising at , a specific impulse greater than 400 s can be achieved by a water-augmented hybrid ram rocket using a non-hydro-reactive fuel. 

Investigation of a Marine Water-Breathing Hybrid Ram-Rocket Motor

An innovative variant of a multiphase marine ramjet is investigated analytically and experimentally. Pressure liquefied gas (LG) is injected, boiling under superheat conditions in the water stream within the propulsion unit, and serving as an on-board bubble source necessary for the ramjet operation. Experiments were conducted in a 10 m diameter tow pool at a speed range of 7–18 m/s (approximately 14–35 knots). For the laboratory concept demonstration and process characterization, two liquefied gases, butane and R134a (synthetic refrigerant gas), were employed. In practical applications, non-polluting LGs such as liquid air may be used. The results reveal the overall performance comparable to the operation with pressurized air, with some thrust advantage of the LG at high-speed tests, attributed to the volume increase of gas during phase change, in accordance with the thermodynamic power cycle analysis.

https://www.mdpi.com/2077-1312/8/9/710/pdf

SSatyanarayanan R. Chakravarthy

Papers

Development of Nano-Al Based Highly Metalized Fuel-Rich Propellant for Water Ramjet Propulsion Applications