Multiple shock compression using a piston of finite weight

Winter, David F.

doi:10.1017/s002211206000058x

Cited by 11 publications

(7 citation statements)

References 2 publications

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“…These fundamental equations together with the proper assumptions and mathematical manipulations for both models (M1 and M2) are available in Refs. [13][14][15].…”

Section: General Description and Function Cycle Of T-s-l-g Gunmentioning

confidence: 99%

“…For each phase, the governing equations representing the gun cycle in powder chamber are similar while the gun process in pump tube are introduced considering the following two cases: (a) isentropic compression of light gas when using heavy piston (model M1), and (b) shock wave formation which propagates and heats BAL-04 3 the light gas when using light piston (model M2, see Ref. [13]). For each model, a computer program was built up to predict the internal ballistic parameters associated with gun firings.…”

Section: Introductionmentioning

confidence: 99%

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Internal Ballistic Solution of a Two-Stage Light-Gas Gun

Aziz

Yakout

Riad

2007

International Conference on Aerospace Sciences and Aviation Tec

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Internal ballistic process of two-stage light-gas gun has been solved by many investigators using different approaches. This paper presents two different approaches to predict the interior ballistic parameters of such gun. The first approach is based on isentropic compression of the light gas in the gun pump, whereas the second approach depends on the theory for piston operated compressor in which shock wave was formed and heated the light gas. For each approach, the governing equations have been used to construct a computer program. Predicted time histories of gun parameters associated with gun firing are presented. The predicted results of each approach are compared with available experimental measurements of other investigators; good agreements are generally obtained. For both approaches, samples of the predicted time histories for powder chamber pressure, pump tube pressure, piston velocity and its travel along the gun tube, and projectile velocity and its travel along the barrel are presented for two calibers (12.7 and 28.6 mm), together with relevant analyses and discussions.

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“…These fundamental equations together with the proper assumptions and mathematical manipulations for both models (M1 and M2) are available in Refs. [13][14][15].…”

Section: General Description and Function Cycle Of T-s-l-g Gunmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Internal Ballistic Solution of a Two-Stage Light-Gas Gun

Aziz

Yakout

Riad

2007

International Conference on Aerospace Sciences and Aviation Tec

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“…Assuming a constant piston accelerating gas pressure p acc (generally p acc < p 6 Here the characteristic lengths Z/i and L 2 of the bypass channel and piston initial location are indicated in Fig. 4a.…”

Section: E Bypass Processmentioning

confidence: 99%

“…In part this philosophy has underlaid development of the light-piston gun tunnel. 5 By making the piston mass as small as possible and, therefore, the piston speed large, shock waves can be produced in the compression 6 and a small amount of entropy generated.…”

Section: Introductionmentioning

confidence: 99%

Bypass piston tube, a new device for generating high temperatures and pressures in gases.

Knoeoes

1968

AIAA Journal

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A new device, the bypass piston tube (BPP tube), for the laboratory production of temperatures exceeding 10 4°K and pressures above 10 3 atm in gases is presented. In principle, the device is essentially a shock tube and a ballistic piston compressor linked in tandem by a bypass channel. With this device a gas can be heated under considerable entropy increase, and the volumetric compression ratio can be kept desirably small. A simple theory for the kinematics and thermo-gasdynamics of the BPP tube, and the anticipated over-all performance are given. Experiments conducted in argon with a small BPP tube are described. The measured temperatures and pressures were of the order T = 1.0 X 10 4°K and p = 0.3 X 10 3 atm, which generally agree with the theory. The BPP tube principle advantageously could be used for high-performance shock-tube drivers (shock speed u s > 12 km/sec, initial pressure pi > 1 mm Hg), for launching of hypervelocity projectiles (projectile speed u p > 10 km/sec), and for producing hypervelocity, high-enthalpy flows in nozzles.Nomenclature a = speed of sound A -BPP tube cross-sectional area D -diameter of compression tube E -= internal energy k = Boltzmann's constant L Bp = length occupied by preheated driver gas before bypass L D = fictitious length defined by total entropy production in •••compression, tube Lk -compression tube length ra = mass of gas particle M -mass of free piston Ms = shock Mach number N = total number of bypassing gas particles p -pressure (p) = average pressure defined by Eq. (2) p -dimensionless pressure p/po q = dimensionless energy loss parameter Q ....= .. total energy loss R = gas constant k/m s -specific entropy t = time t = dimensionless time t/.r T = temperature f = dimensionless temperature T/T Q W = pressure work x = piston distance to end wall x = dimensionless distance X/XQ y = specific heat ratio A£ = duration of bypass process £ = dimensionless filling parameter denned by Eq. (6) p = density T = characteristic time for piston bounce, T = (Mxo/Apo) llz Subscripts f -"final" gas condition in piston bounce fill = ideal, homogeneous gas condition after "filling" of compression tube r = condition of driver gas behind reflected shock wave 0 = reference gas condition for isentropic bounce 1 = initial driver-gas condition 2 = condition of driver gas behind incident shock wave 4 = initial condition of accelerating gas 5 = condition of driver gas before bypass 6 = condition of driver gas after passage of unsteady expansion wave in bypass process

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“…Because these entropy changes themselves increase with piston speed, the maximum piston velocity produced will be taken as a measure of performance. A method for calculating the final temperature corresponding to a given piston speed is outlined by Winter (1960), where it can be seen that for piston speeds above about twice the speed of sound in the test gas, and a fixed ratio of initial and final pressures, the final ideal gas temperature becomes roughly proportional to the piston speed.…”

Section: Introductionmentioning

confidence: 99%

An approximate theory of gun tunnel behaviour

Stalker

1965

J. Fluid Mech.

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Approximate methods are used in a theoretical investigation of piston acceleration, peak pressure and piston oscillations in a gun tunnel. Behaviour in all these respects, at a given ratio of initial driver and test gas pressures, is related to the value of a ‘gun tunnel parameter’, Λ, and the ratio of the speeds of sound in driver and test gases. It is shown that large values of Λ must be combined with an enhanced speed of sound in the driver if high performance is to be achieved with manageable peak pressures. With air as test gas, using values of Λ achieved in current practice and a suitable driver gas, the analysis indicates that piston speeds approaching four times the speed of sound in air may be obtained.

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Multiple shock compression using a piston of finite weight

Cited by 11 publications

References 2 publications

Internal Ballistic Solution of a Two-Stage Light-Gas Gun

Internal Ballistic Solution of a Two-Stage Light-Gas Gun

Bypass piston tube, a new device for generating high temperatures and pressures in gases.

An approximate theory of gun tunnel behaviour

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