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Infrared Sources
Published in Monroe Schlessinger, Infrared Technology Fundamentals, 2019
Most rocket engines are designed to maximize the specific impulse (Isp) attained for the propellants used. This involves both the rocket thrust produced and the rate of flow of combustion gases through the nozzle throat and eventually out of the nozzle. As a result, in most rocket engines the products of combustion usually contain substances (such as H2 and CO) that are still combustible. When these reach the atmosphere, they combine with the available oxygen to create afterburning in the exhaust plume.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Specific impulse - The amount of thrust force obtained from a fuel/oxidizer/engine combination when a unit weight of fuel is burned in 1 second. The units of specific impulse are seconds because the force and weight units cancel.
Elements of Rocket Propulsion
Published in D.P. Mishra, Fundamentals of Rocket Propulsion, 2017
Then, Isp=mpVeqmpg=Veqg=Fm˙pgIt must be noted that Isp does not depend on the flight velocity. The presence of g in the definition of Isp is arbitrary. But it makes the unit of Isp uniform in all common systems of units. Note that the specific impulse depends on both the type of propellant and the rocket engine configuration. Besides this, the specific impulse Isp can be stated as the amount of impulse imparted to vehicle per kilogram of effective propellant. Note that Isp can also be defined as thrust per unit weight flow rate consumption of propellant. Hence, lower m˙p implies higher Isp, which is desirable for chemical rockets. A higher specific impulse Isp is directly related to long flight range, which indicates superior range capability of air-breathing engine over chemical rockets at relatively low speeds. Note that in liquid-propellant engine, propellant flow rate and thrust can be measured easily and thus specific impulse Isp can be easily estimated experimentally. But in case of solid-propellant rocket engine, it is quite cumbersome to measure the propellant flow rate accurately and hence specific impulse Isp can be determined from the total impulse and propellant weight using Equation 3.15. Typical values of specific impulse Isp for various types of rocket engines are given in Table 3.1. It can be noted that specific impulse Isp of solid-propellant rocket engine varies between 200 and 300 s, while liquid-propellant rocket exhibits its value between 300 and 400 s. The values of Isp for hybrid rocket engine are higher than that of solid-propellant rocket engine. Of course, nonchemical rocket engines have higher values of Isp. But these engines have capability of producing very less thrust. Therefore, it is only preferred for deep-space applications.
Systematic Component Investigation of the Steady-State High-Temperature In-Pile Nuclear Thermal Propulsion Experimental Test Bed
Published in Nuclear Technology, 2022
Tyler R. Steiner, Richard H. Howard
A nuclear thermal rocket (NTR) produces thrust by heating, typically hydrogen propellant through a nuclear reactor core at roughly 2500 K (Ref. 1). This offers advantages over conventional chemical rockets by utilizing a less massive propellant and producing a larger specific impulse. A larger specific impulse presents the capability for faster transit times. Reducing travel time is essential to limit the deleterious effects of space radiation on the spacecraft’s crew and electronic systems. The nuclear thermal propulsion (NTP) environment consists of high-temperature hydrogen in a radiation field. Experimental testing is necessary to qualify components in such a harsh environment.
Computational investigation of cooling effectiveness for film cooled dual-bell exhaust nozzle for LO2/LH2 liquid rocket engines
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Martin Raju, Abhilash Suryan, David Šimurda
Specific impulse () is the thrust generated by a rocket engine per weight flow rate of fuel consumed. Specific impulse loss due to secondary coolant injection is due to the excess fuel consumption used to cool the nozzle walls. As the coolant is injected at the inflection, which is situated downstream from the inlet of DBN, it does not take part in the combustion process unlike in case of combustion chamber cooling (Batha et al. 1963). Specific impulse is calculated using the equation given below: