China
Africa
Explore chapters and articles related to this topic
Significance and Administration of Nanotechnology in the Armed Forces and Defense Sector
Published in Cherry Bhargava, Amit Sachdeva, Pardeep Kumar Sharma, Smart Nanotechnology with Applications, 2020
Ali Asgher Ali Hasan, Roshan Rajesh Bhatkar, Sarath Raj Nadarajan Assari Syamala
Similarly to solid propellants, liquid propellants are classified further based on their synthesis in proportions with other similar, high-energy releasing chemical base additives such as the combination of fuels and oxidizers. This categorization of liquid propellant based on monopropellant or bipropellant base combustion behavior is as follows [4,7]:Single-Based Liquid Propellants: Recognized as monopropellants where there is a singular base propellant ignited using an ignition assembly. The most widely used monopropellant is hydrazine (N2H4). The decomposition of hydrazine occurs at two stages of chemical reaction. The first stage of reaction is where two molecules of hydrazine break down to two molecules of ammonia and hydrogen gas. The precursory reaction is exothermic in nature and releases huge amount of heat to initiate the lift off. The second stage is where ammonia decomposes further into individual nitrogen and hydrogen molecules. The second stage of reaction is endothermic in nature and happens at an expense of reduction in thrust by reducing the initial amounts of energy required to perform a successful lift-off. More examples of Single-Base Liquid Propellants are: nitro methane, methyl or dimethyl derivatives of hydrazine such as the symmetrical mono-methyl hydrazine or the unsymmetrical dimethyl hydrazine, hydrogen peroxide (stable at ordinary temperatures but decompose to hot unstable gases at elevated temperatures) and etc. [8,9].Double-Based Liquid Propellants: As the name suggests, here we have two high-energy releasing compounds, which initiate the combustion process the moment they are added together. In double-based liquid propellant systems, the two high-energy releasing chemicals are: (i) Fuel and; (ii) Oxidizer. Fuel can either be kerosene (RP-01), alcohol, hydrazine, and its derivatives (UDMH or MMH) along with liquid hydrogen. Oxidizers can be nitric acid (HNO3), nitrogen tetroxide, liquid oxygen, and liquid fluorine. Liquid oxygen and liquid fluorine are the optimum fuel oxidizers, but they have to be stored in cryogenic environments that pose a major constraint in the utility of these two strong fuel oxidizing agents [8,9].
An innovative ship salvage concept and its effect on the hull structural response
Published in Journal of Marine Engineering & Technology, 2020
Ilias Zilakos, Elias Chatzidouros, Nicholas Tsouvalis
For the case of the external devices deployment scenario, special mixtures of various gases can, in general, be used to inflate the balloons (Bryant 1970). Within the framework of SuSy project, several types of gas production systems have been investigated. Among the prevailing candidates are pressurised systems (e.g. Nitrogen, Carbon Dioxide), catalytic decomposition systems (monopropellant system, e.g. Hydrazine, Nitrous Oxide) and finally solid-fuelled (e.g. Ammonium Perchlorate, Ammonium Nitrate) and liquid-fuelled systems (bipropellant system, e.g. Nitric Acid + Ammonia, Nitrous Oxide + Butane), a well-known technology used in rocket propulsion applications. Apart from the pressurised systems the rest of the gas production systems result to a small specific volume configuration and can inflate the balloons in very short time, compensating large external hydrostatic pressures, corresponding to large sea depths. Solid fuel or liquid fuel systems might be well suited for wreckage removal off the seabed at large sea depths, where high internal balloon pressures are required in order to compensate for the large hydrostatic pressure. On the other hand, such systems are not well suited for use on-board a tanker due to their flammable and explosive nature (Bryant 1970), leaving the pressurised systems as a safer and more suitable option.
Stability and stabilisation of switched time-varying delay systems: a multiple discontinuous Lyapunov function approach
Published in International Journal of Systems Science, 2020
Mohammad Mahdi Saberi, Iman Zamani
A model of combustion in rocket motor chambers (Zheng & Frank, 2002), is considered here for stabilisation with sliding mode control, to illustrate the effectiveness of the obtained results in practical applications. This model represents a liquid monopropellant rocket motor with a pressure feeding system. Under the assumption of nonsteady flow and lumped lag factor, an appropriate linearised model can be in the form of switched delay systems (1) with the following coefficients (Mahmoud, 2010): and , where represents the mode of operation, and Tables 5 and 6 show the data and Parameters of Example 4.
An overview over dinitramide anion and compounds based on it
Published in Indian Chemical Engineer, 2020
Bottaro et al. [14] were credited for first synthesising the ADN crystals in their lab in the USA. They are fascinated with DA and studied a lot over various DA and DA-based compounds. They were in particular fascinated over ADN [NH4N(NO2)2]. ADN has the potential to replace AP in solid propellants, and hydrazine in liquid monopropellant [15]. ADN undergoes highly exothermic combustion reactions near the surface leading to the efficient heat feedback to the deflagrating surface enhancing the burning rate [16]. Severe ADN hygroscopicity, needle-shaped crystalline structure and compatibility issues with energetic binders are some of the problems associated ADN. FLP-106 is a low viscous yellowish liquid with high performance, low vapour pressure and low sensitivity. It consisted of water and 64.6% ADN. The only disadvantages associated with its high combustion temperature, which is 800°C higher than hydrazine [10,17]. A detailed study over ADN crystal structure was performed by Ritchie et al. [18]. Apart from ADN, there are several other synthesised dinitramides-based compounds which are discussed from next paragraph.