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Gas Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
Turbine and propeller engines use air from atmosphere, while rocket engines contain oxygen (oxidizer) within itself. Fuel and oxidizer are mixed and exploded in the combustion chamber, and the hot exhaust gases produced during combustion pass through the nozzle to accelerate the flow and produce the thrust required to propel the rocket. Turbine and propeller engines cannot operate in outer space since there is no atmosphere, but a rocket works in space. There are basically two types of rocket engines: liquid propellant and solid propellant. In the former case, the propellants (fuel and oxidizer) are stored separately as liquid and are sent to the combustor of the nozzle in which combustion takes place. In the latter case, the propellants are mixed together and packed into a solid cylinder. Burning takes place when propellants are exposed to a source of heat supplied by an igniter. The burning continues until all the propellants are exhausted. Due to the pumps and storage tanks, liquid propellant rockets tend to be heavier and complex compared to that of solid propellant that can be handled with ease.
Project in Rocketry
Published in G. Boothroyd, C. Poli, Applied Engineering Mechanics, 2018
A rocket engine produces gas molecules which are ejected with a high velocity; this causes a reaction which propels the rocket forward. To predict the motion of the rocket, it is necessary to obtain an equation which relates the forces acting on the rocket to its instantaneous acceleration. Forces are generally not applied to objects at a point but are distributed in their effect over a finite area. Under these circumstances, it is more useful to refer to a pressure; this is a force divided by the area over which the force is exerted. One effect of the ejection of gas molecules from a rocket engine is to produce a pressure at the rocket engine nozzle which helps to propel the rocket forward. The effect of this pressure is reduced to some extent by the pressure exerted by the atmosphere (atmospheric pressure). Thus, the effective pressure at the nozzle is found by subtracting the atmospheric pressure from the pressure of the exhaust gases. The force Fp resulting from this pressure is then found by multiplying the effective pressure p by the cross-sectional area A of the rocket nozzle.
Jet-Swirl Injector Spray Characteristics in Combustion Waste of a Liquid Propellant Rocket Thrust Chamber
Published in Dzaraini Kamarun, Ramlah Mohd. Tajuddin, Bulan Abdullah, Engineering and Technical Development for a Sustainable Environment, 2017
Zulkifli Abdul Ghaffar, Salmiah Kasolang, Ahmad Hussein Abdul Hamid
Generally, there exist two types of rocket which are liquid propellant rocket and solid propellant rocket. The liquid propellant rocket is a rocket with the propellants is stored separately as liquids and are injected to the thrust chamber [1]. Liquid propellant rocket are generally used for large rockets such as space launch vehicles and ballistic missiles. Solid propellant rocket are much lighter so they are used in smaller missiles such as air-launched and shoulder-launched missiles. Schematic of one type of liquid propellant rocket (liquid bipropellant rocket) is shown in Figure 13.1.
Envisioning a sustainable future for space launches: a review of current research and policy
Published in Journal of the Royal Society of New Zealand, 2023
Tyler F. M. Brown, Michele T. Bannister, Laura E. Revell
The launch industry today relies on four major fuel types for current rocket propulsion: liquid kerosene, cryogenic, hypergolic and solid. The combustion of these propellants creates a suite of gaseous and particulate exhaust products, including (but not limited to) carbon dioxide, water vapour, black carbon, alumina, reactive chloride and nitrogen oxides (Dallas et al. 2020). Individual rockets may contain component stages that include various propellant types, which makes quantifying these emissions essential to understanding their environmental impact. The scale of this emission, however, is still relatively poorly understood. In-situ measurements of exhaust plumes are limited, and most current data rely heavily on plume modelling or best estimates from combustion calculations. Even the most ubiquitous fuel, liquid kerosene, is still relatively poorly modelled in exhaust concentrations (Sheaffer 2021).
Multiscale Simulations of Thermal Transport in W-UO2 CERMET Fuel for Nuclear Thermal Propulsion
Published in Nuclear Technology, 2021
Marina Sessim, Michael R. Tonks
Nuclear thermal rockets offer a considerable advantage over chemical rockets because they can provide long periods of constant thrust.4,5 The nuclear core produces energy by fission and is cooled by gaseous hydrogen, which acts as the propellant that provides the necessary thrust. The propellant flows through the subchannels of the fuel elements and absorbs thermal energy, producing an axial temperature difference exceeding 2000 K (Ref. 6). Then, the high-temperature hydrogen gas is exhausted through a nozzle and produces a reaction force that moves the rocket forward. The maneuvers required to reach Mars require multiple restart and short-burn propulsion cycles of the reactor7,8 such that the fuel must maintain structural integrity for a combined burn time of under 2 h at very high temperature (2800 to 3000 K) (Refs. 5 and 7). Moreover, a bimodal form of operation has been considered in which the reactor operates at low power and temperature between propulsion cycles to supply a source of electric power [hundreds MW(electric) to 1 MW(electric)] to the spacecraft.5,7 The bimodal operation is hard on the fuel due to the combined effects of long-term radiation damage at low temperature and the short high-temperature propulsion cycles. Thus, the fuel conditions in an NTP reactor are quite different from the conditions in a reactor for power generation. For this reason, the design and fabrication of the fuel are a major technological hurdle.1
Afterburning effect on thermal environment of four-engine liquid rockets at different altitudes
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Zhitan Zhou, Yiyin Bao, Peijie Sun, Guigao Le
In rocket engines, the combustion reactions of the propellant produce enormous amounts of energy, which generates a gas flow along an established direction with the help of the Laval nozzle. The supersonic exhaust gas flow can produce thrust for rocket launch (Crocco et al., 1964; Whitefield et al., 2000; Zhou, Wang, et al., 2020). The exhaust gas from the Laval nozzles, which has a high pressure and temperature, expands rapidly in the external environment and forms reverse plume, and then, it heats the rocket base. Compared with single-engine rockets, the thermal environment of multiple-engine rockets is more complex due to the interaction of multiple-plumes (Xiong et al., 2020). Due to the gasdynamic continuously heating over the launch vehicle by exhaust gas, the high-temperature region occurs at the rocket base and may cause significant erosion and damage (Mehta, 1981). In order to ensure the security of the rocket flight, effective thermal protection should be designed in the launch vehicle.