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Developmental Study of Aluminized Fuel-Rich Propellant
Published in Debi Prasad Mishra, Advances in Combustion Technology, 2023
Nikunj Rathi, P.A. Ramakrishna
Typically, ramjets are liquid fuelled and use kerosene as fuel and air as oxidizer. Being a liquid fuel, it has to atomize, vaporize, mix and then react with the incoming compressed air. This increases the residence time required or the length of the combustion chamber for complete reaction. Also, kerosene has a density of 800 kg/m3. On the contrary, a solid fuel ramjet (SFRJ) utilizes solid fuel-rich propellant, which has a higher density of around 1500 kg/m3, making the overall system compact.
Gas Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
A ramjet engine is a type of air-breathing jet engine, which makes use of vehicle’s forward motion to compress the incoming air and requires no rotating compressor. Fuel is injected into the combustion chamber in which mixing of fuel and hot compressed air takes place and ignition occurs. Ramjet operates in the supersonic speeds, typically in the Mach number range of 3–6. However, they become less efficient at hypersonic speeds.
Pulsejet and Ramjet Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
Although a ramjet can operate at subsonic flight speed, the increasing pressure rise accompanying higher flight speeds renders the ramjet most suitable for supersonic flight and most efficient at speeds around Mach 3. For this reason, subsonic ramjets are seldom (if ever) used these days.
Bayesian Model Calibration Using High-Fidelity Simulations of a Mach 8 Scramjet Isolator and Combustor
Published in Combustion Science and Technology, 2023
Supersonic combustion ramjets (scramjets) are air-breathing hypersonic propulsion devices that use shock-based compression to generate thrust. The complex physical phenomena in these devices – namely, supersonic combustion, turbulence-chemistry interactions, and shock-boundary layer interactions – have made them difficult to study since their conception (Curran 2001; Gaitonde 2015; Liu, Baccarella, and Lee 2020; Smart 2007; Urzay 2018). In general, high-fidelity studies at relevant flight conditions are preferred because they give the greatest insight into the relevant physics. However, these studies pose many challenges in both computational and experimental contexts. Direct numerical simulations (DNS) of scramjets are infeasible with current computing architectures, and comparatively cheap large-eddy simulations (LES) can still incur great computational cost (Fulton et al. 2014; Larsson et al. 2015; Nordin-Bates et al. 2017). On the other hand, ground-based experiments tend to be expensive and short-duration, with test conditions that are specialized to the facility (Abul-Huda and Gamba 2015; Baccarella et al. 2017; Gruber and Nejad 1994; Hannemann et al. 2018; Stalker et al. 2005). As a result, high-fidelity scramjet data sets are generally sparse, which makes design sensitivities and performance envelopes difficult to ascertain. This poses major challenges for developing scramjet designs that are robust under a range of possible flight conditions.
Combustion Characteristics of Boron-HTPB-Based Solid Fuels for Hybrid Gas Generator in Ducted Rocket Applications
Published in Combustion Science and Technology, 2019
Syed Alay Hashim, Srinibas Karmakar, Arnab Roy
The ramjet engine is considered to be an attractive propulsive device which offers simplicity, higher thrust, higher specific impulse, safety and working stability as compared to an equivalent rocket motor (Fry, 2004). Refinement of the fundamental design of solid fuel ramjet (SFRJ) engine has happened over last several decades and continues to be an active research area till date. In this field, Gany and Netzer and few other researchers have been working for last several years to build a small-scale ramjet combustion chamber which could be utilized to support analytical and numerical studies (Mady et al., 1978; Netzer, 1978; Netzer and Gany, 1991). The SFRJ have also been used to examine high-density fuel formulations containing polymer with embedded metal particles (Gany and Netzer, 1986; Natan and Gany, 1991). The most commonly used fuel is hydroxyl-terminated polybutadiene (HTPB) which also works as a binder for additives (Chiaverini et al., 1999) and provides higher specific impulse (Jain, 2002). Use of HTPB is significant to the propulsion community due to its extensive application in solid propellant rocket motors. The widespread use of HTPB is due to its desirable mechanical properties at a wide range of temperatures, even when it is highly loaded with metal particles (Muthiah et al., 1992, 1991).
Internal Ballistics of a Boron-Containing Solid Fuel Ramjet
Published in Combustion Science and Technology, 2021
Hertzel Kadosh, Benveniste Natan
The Ramjet engine is a simple air-breathing device without any moving parts such as the compressor and turbine. The basic idea behind ramjet propulsion is the aerodynamic compression of air, making it suitable for supersonic flight speed. At Mach numbers of 2–4, the ramjet is highly efficient and has superiority over other types of engines.