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Are All Rockets the Same?
Published in Travis S. Taylor, Introduction to Rocket Science and Engineering, 2017
In Sections 5.1 and 5.2, we discussed the solid rocket and the liquid rocket engines, respectively. The solid uses a mixture of fuel and oxidizer that solidifies into the propellant material. The liquid engine uses a liquid oxidizer and fuel and mixes them together in a combustion process. It is possible to use a solidified fuel only and flow an oxidizer through the perforation. This type of engine is called a hybrid rocket engine. Figure 5.14 shows a schematic of a hybrid rocket. Gas pressurization is generated by heating some of the liquid oxidizer similar to the way it is done for a liquid engine. The oxidizer is flowed through the perforation of the solid fuel where it is ignited. Oxidizer is only present on the burning surface of the solid fuel, and, therefore, it will only burn when the oxidizer is flowing. This concept allows for the shutdown and restarts of the engine, which cannot be accomplished with a solid motor, as discussed in Section 5.2.4. Also, various perforation configurations can be implemented as with a typical solid motor to alter the burn rates and thrust profiles.
Hybrid Propellant Rocket Engine
Published in D.P. Mishra, Fundamentals of Rocket Propulsion, 2017
A hybrid rocket engine is one in which both liquid and solid propellants can be used simultaneously. For example, oxidizer can be in liquid phase, while fuel can be in solid phase or vice versa. Several combinations of solid/liquid fuels and liquid/solid oxidizers have been used by researchers for the design and development of hybrid rocket engines. However, liquid oxidizer and solid fuel is preferred in hybrid rocket engine design. The other combination of solid oxidizer and liquid fuel is not preferred as most of the solid oxidizers are available in crystal form, which cannot be cast in a specific form of propellant grain.
Engine performance
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
The liquid-fuel rocket (Figure 4.25) typically pumps separate fuel and oxidizer components into the combustion chamber, where they burn. Solid propellants are prepared as a mixture of fuel and oxidizing components, and the propellant storage chamber becomes the combustion chamber. Hybrid rocket engines use a combination of solid and liquid or gaseous propellants.
Three-dimensional printed metal-nested composite fuel grains with superior mechanical and combustion properties
Published in Virtual and Physical Prototyping, 2022
Xin Lin, Dandan Qu, Xuedong Chen, Zezhong Wang, Jiaxiao Luo, Dongdong Meng, Guoliang Liu, Kun Zhang, Fei Li, Xilong Yu
Hybrid rocket engines (HREs) combine the intrinsic advantages of liquid propellants and solid fuels, which renders it simple structure, high safety and reliability, adjustable thrust, and lower cost than conventional rocket engines (Whitmore, Sobbi, and Walker 2014; Wang et al. 2021a; Cai et al. 2013; Fang et al. 2021; Zilliac et al. 2020; Kahraman, Ozkol, and Karabeyoglu 2021). These advantages make HREs attractive with regard to a broad range of space applications, such as sounding rockets (Sella et al. 2020; Bouziane et al. 2019; Broughton et al. 2018; Marciniak et al. 2018), upper stage propulsion units (Jens, Cantwell, and Hubbard 2016; Casalino and Pastrone 2008) and commercial manned spacecrafts (Cai et al. 2013; Mazzetti, Merotto, and Pinarello 2016). However, HREs have several associated challenges, the most significant being the low regression rates of classical polymeric fuels. The issue of low regression rates has thus far seriously restricted the implementation of HRE technology in large-scale thrust applications (Kobald et al. 2017).
Characterisation of paraffin-based hybrid rocket fuels loaded with nano-additives
Published in Journal of Experimental Nanoscience, 2018
Md. Zishan Akhter, M. A. Hassan
Hybrid rockets fuel offer several advantages over the conventional rocket fuel based systems. It combines the benefits of both solid and liquid fuels. Advantage of hybrid fuel include reduced de-bonding and crack sensitivity, fuel insensitivity to combustion instability, and increased specific impulse (Isp) in comparison to its solid counterpart. Hybrid fuel-based rocket engines offer the possibility of throttling and on-demand thrust termination/restart. Likewise, superiority of hybrid rocket system over the liquid ones broadly includes intrinsic safety from explosion hazard due to phase-separation among propellants. It also leads to simpler engine design due to the expulsion of regenerative cooling system from nozzle and combustion chamber. Hybrid propellants demonstrate greater flexibility in fuel/oxidiser selection with minimal environmental impacts. These features make it a suitable alternative to the conventional systems for various space applications such as, sounding rockets, first-stage boosters, upper-stage launch vehicles, orbital injection systems, and sub-orbital and orbital human space flight involving space tourism [1]. However, there are certain limitations associated with hybrid propulsion system such as low fuel regression rate and varying mixture ratio (O/F) during combustion. The low regression of polymeric fuels and the subsequent poor combustion efficiency is largely attributed to the diffusion-flame-limited-combustion model of hybrid propulsion system [2].
Additively manufactured aluminium nested composite hybrid rocket fuel grains with breathable blades
Published in Virtual and Physical Prototyping, 2023
Dandan Qu, Xin Lin, Kun Zhang, Zhiyong Li, Zezhong Wang, Guoliang Liu, Yang Meng, Gengxing Luo, Ruoyan Wang, Xilong Yu
Hybrid rocket propulsion technology has increasingly received interest in the last two decades (Guo et al. 2022; Wang et al. 2021a; Whitmore, Peterson, and Eilers 2013; Zhang et al. 2022a). Several parallel major advances (Okninski et al. 2021; Research Flights 2021 Virgin Galactic 2021; Faenza et al. 2019; First Test Flight of PERUN Rocket Demonstrator 2020; Wei et al. 2022) have shown that hybrid rocket propulsion is a potential game changer for space transportation owing to its inherent high safety and low cost. However, typically used polymeric fuels such as hydroxyl-terminated polybutadiene have a low regression rate as a consequence of classical diffusion-flame-limited combustion (Oztan et al. 2021; Wang et al. 2022a). The issue of a low regression rate leads to low thrust levels for common fuel grains with single-port geometries and hence seriously hinders the potential widescale application of hybrid rockets. Paraffin-based fuels (DeLuca et al. 2017; Karabeyoglu et al. 2004; Wang et al. 2022b) are a low-cost and effective solution for increasing the regression rate owing to their inherently liquefiable characteristics; i.e. melt layer fluctuations and droplet entrainment. Despite these advantages, the mechanical strength of paraffin alone is poor compared with that of conventional polymer fuels, which leads to the use of reinforcing additives, such as elastomers and thermoplastics. This approach improves the mechanical properties at the cost of increasing the viscosity of the melt fuel, which prevents a high regression rate of the paraffin fuel. The variety and proportions of enhanced additives result in an inherent trade-off between the mechanical stability, regression rate, and processability. Unfortunately, the underlying mechanism and evaluation criteria for this trade-off are complex.