Modeling of Pellet Acceleration by Two-Stage Guns

Riva, G.; Reggiori, A.

doi:10.13182/fst89-a25352

Cited by 20 publications

(8 citation statements)

References 2 publications

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“…The model was developed starting from well-known models already developed. 8,17,18 The model of Milora et al 17 is user-friendly, but does not take into account the heat exchange of the gas with the wall. Riva/Reggiori's 8,18 model, on the other hand, explicitly takes into account this heat exchange and gas blow-by between the gun wall and the piston's external surface, but its formulation is a little bit more complicated to implement in a form which is useful for a full system optimization.…”

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

“…The model implemented in this work is based on the equation written by Milora et al 17 for the Quickgun algorithm, and the heat exchange term and the blow-by terms suggested by Riva/Reggiori. 8,18 The code was then implemented in a symbolic language 19,20 building up macroblocks simulating all the main subsystems. The model also takes into account the possibility of using two gases together.…”

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

“…8,17,18 Several studies have been conducted in other laboratories 2 to evaluate the effect of the nonideal properties of gases on propellant behavior, highlighting that a real gas at a high temperature could be a better propellant than a perfect gas at the same temperature and pressure. Nonetheless, to simulate the behavior of the gas in the second stage, the hypothesis of an ideal gas is normally accepted.…”

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

“…Nonetheless, to simulate the behavior of the gas in the second stage, the hypothesis of an ideal gas is normally accepted. 8,17,18 Although, no specific tests have been done in our laboratory to verify this assumption, the overall calibration procedure is validated by the evidence that experimental results are correctly predicted in all the working conditions of the gun. The numerical model was calibrated and tuned by comparing the model outputs with experimental results 21,22 and proved to be a reliable tool in predicting the gun performance for a wide operational range 21,22 from a few hundred bars to a few thousand bars of maximum pressure produced in the pump tube.…”

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

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A system to damp the free piston oscillations in a two-stage light-gas gun used for hypervelocity impact experiments

Pavarin

Francesconi

Angrilli

2004

Review of Scientific Instruments

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Hypervelocity impact experiments that reproduce on-orbit collisions between micrometeoroids or orbital debris and space structures are commonly performed by means of propellant-driven twostage light-gas guns. Such devices accelerate projectiles using the thrust of a light propellant gas that is compressed to high pressure and temperature by a piston running in a pump tube. Though these guns have the unique capability of accelerating particles up to 9 km/s, many components of the gun must be checked and/or substituted after each shot making test sessions long and expensive. In order to have a lot of and many different types of hypervelocity impact data, the Center of Studies and activities for Space CISAS ”G. Colombo” of Padua University developed a high-shot-frequency two-stage light-gas gun that can increase the shot repetition rate of standard facilities by a factor of 5 or more and at the same time reduce the shot cost by a factor of 2 or more. This is made possible through the use of special mechanical and diagnostic solutions that were designed to operate the gun for more than 50 shots in sequence without having to carry out maintenance operations. This article presents the design and operation of the CISAS two-stage light-gas gun damping system, which is one of the subsystems that makes it possible to achieve high-shot frequency. The damping system is in charge of controlling the piston oscillations in the pump tube, making it possible for the piston to withstand more than 100 shots without any damage. In particular, the damping system avoids piston strikes onto the gun head at the end of each compression stroke and allows the piston to be positioned at the base of the pump tube after each shot. The sensitivity of the piston oscillations to the damping operations and main subsystem design parameters were identified using numerical simulations, carried out according to a model that describes every working phase of the gun. Moreover, in this paper, the technical solutions for the damping system implementation are presented and the numerical predictions are compared with experimental results. For the CISAS high-shot-frequency gas gun, an efficient damping system proved to be a fundamental requirement to reliably accelerate 100 mg projectiles above 5 km/s and 70 mg projectiles at 5.5 km/s with a shot frequency of 10 shots per day at least, including the time needed for replacing the target and pumping down the target vacuum chamber

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Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

Section: The Cisas Gun Numerical Modelmentioning

confidence: 99%

See 2 more Smart Citations

A system to damp the free piston oscillations in a two-stage light-gas gun used for hypervelocity impact experiments

Pavarin

Francesconi

Angrilli

2004

Review of Scientific Instruments

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“…Impulse piston units are employed in two-stage light-gas guns for the acceleration of projectiles to velocities of over 2 km/s (for example, [43][44][45]), in space research [46], in thermonuclear fusion research [47,48], and in studies of synthesis of materials and new states of substances [49]. Shmelev and Nikolaev [50] studied the possibility of modification of the thermodynamic cycle of an internal combustion engine by realizing modes of nonisentropic compression and combustion of working mixture in the cylinder.…”

Section: Introductionmentioning

confidence: 99%

Heat-engineering units for the generation of dense high-temperature gas

Volov

2006

High Temp

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Various methods of gas compression are reviewed, which are intended for heating the gas. Special attention is given to units of nonisentropic compression of the mechanical heat-engineering type, in which the gas is transferred from chamber to chamber in order to increase the temperature. The units are subdivided into classes or systems, namely, those of impulse, pulse-periodic, and continuous operation. Methods are discussed of mathematical description of processes occurring in units of this type, including analytical investigation of simplified qualitative models and numerical simulation in more complex cases close to reality. CONTENTS

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