Definition of specific impulse

Greenwood, S. W.

doi:10.2514/3.27809

Cited by 10 publications

(2 citation statements)

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“…The ignition delay (ID) time is one of the most important criteria of IL performance, provided that hypergolic ignition occurs; the components and structure of ILs impact both the ID time and the ignition process, whereas in macroscopic terms, the viscosity of ILs and the experimental method (e.g., the velocity of contact, ambient temperature, and size of the droplet) are also influencing factors. − In addition, specific impulse is also an important performance parameter for rockets. Except for the structural design of rockets, the choice of propellant is also a factor in determining the specific impulse . Specific impulse can be increased by decreasing water content in an oxidizer, or increasing heat of formation and energy-density of fuel. , [EMIm]DCA is a less-than-spectacular fuel with respect to specific impulse compared with RP-1 and hydrazine derivatives.…”

Section: Introductionmentioning

confidence: 99%

“…Except for the structural design of rockets, the choice of propellant is also a factor in determining the specific impulse. 13 Specific impulse can be increased by decreasing water content in an oxidizer, or increasing heat of formation and energy-density of fuel. 14 , 15 [EMIm]DCA is a less-than-spectacular fuel 5 with respect to specific impulse compared with RP-1 and hydrazine derivatives.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Adding Carbonaceous Fuels to Ionic Liquids on Propellant Properties

Gao

Tan

et al. 2022

ACS Omega

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To make ionic liquids (ILs) accessible and economical, ethylene glycol was mixed in 1-ethyl-3-methylimidazolium-dicyanamide ([EMIm]DCA) to obtain droplets that could experimentally collide white fuming nitric acid. To investigate the ignition delay (ID) time theoretically in terms of hydrodynamics, alcohol fuels and kerosene were used as combustibles, while the intermiscibility between them and nitric acid (HNO 3 ) was calculated using the ternary phase-field method alongside finite element analysis. The specific impulses of blend fuels were calculated by a thermodynamic method and compared to ILs. When the droplet was ethylene glycol/ [EMIm]DCA with a 2.1 mm diameter and a 1.69 m/s colliding velocity, the ID time was the shortest. Kerosene was not an applicable additive for [EMIm]DCA owing to its lower intermiscibility with ILs and HNO 3 than alcohol fuels; alcohol fuels, however, were appropriate. The concentration of ethylene glycol in the oxidizer pool increased faster than the concentration of propylene glycol, triggering more rapid hypergolic ignition in the first 50 ms. The protocols regarding the hypergolic ignition conditions were verified, i.e., the size of the droplet had to be minute when the colliding velocity was as fast as possible; this was carefully calculated using ethylene glycol. According to thermodynamic calculations, the addition of alcohol fuels can improve the specific impulse of fuels, with ethylene glycol performing the best. The feasibility of adding alcohol fuels to ILs was confirmed via experiments and thermodynamic computations, with the simulation results providing some guidance on selecting the experimental or engineering conditions or both.

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