Bow shock stand-off distance for subsonic decelerating bodies

Roohani, H.; Gledhill, Irvy Ma; Mahomed, I.; Skews, B. W.

doi:10.1007/s00193-019-00921-3

Cited by 5 publications

(7 citation statements)

References 27 publications

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“…In general, the acceleration drag coefficient was smaller than that in the steady state at a given Mach number M, whereas the deceleration drag coefficient was greater compared to steady state at a given M. This observation was similar for a NACA0012 aerofoil [4] studied for a wider Mach number range between 0.5 and 1.5 at 106g acceleration magnitude and is largely attributable to lag in the flow field, described as flow history.…”

Section: Drag Coefficientmentioning

confidence: 53%

“…The free-flight ballistic range experiment by Saito et al [1] was numerically modelled in ANSYS Fluent by Roohani et al [4] and provided validation of the ST acceleration technique. This ballistic range experiment studied the bow-shock standoff distance for spheres decelerating through the transonic regime.…”

Section: Unsteadymentioning

confidence: 99%

“…While the range of "significant acceleration" is yet to be quantified, earlier research found acceleration effects on a NACA0012 aerofoil in the transonic regime were strongly present at 100g, a value now common in missile manoeuvre. Examples described below include the persistence of detached bow shocks ahead of projectiles decelerating under drag in ballistic ranges to projectile speeds well below the speed of sound [1,2,4]; wake and separation shocks which overtake decelerating projectiles, changing the pressure at the stagnation point [5]; and shocks that appear critical at Mach numbers well above the steady state equivalents in accelerated flow. As missiles are designed for more agility, it becomes increasingly necessary to provide an overview of the flow physics involved in these cases.…”

Section: Introductionmentioning

confidence: 99%

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Unsteady shock wave dynamics in accelerating and decelerating flight

et al. 2021

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Increasingly agile manoeuvre is an advantage in the flight of aircraft, missiles and aerial vehicles, but the principles of accelerating aerodynamics in the transonic regime are only now being fully investigated. This study contributes to the understanding of shock and separation effects on drag during axial acceleration, using a simple geometric configuration. Unsteady shock wave behavior was numerically investigated for an axisymmetric cone-cylinder using a commercial solver and the Moving Reference Frame acceleration technique. This acceleration technique was validated using unsteady numerical and experimental methods. The cone-cylinder was accelerated from Mach number 0.6 to Mach number 1.2 at 100g constant and deceleration was from Mach number 1.2 until Mach number 0.6 at –100g constant. Three cone angles were tested for the cone-cylinder with uniform cylinder diameter. Acceleration through the transonic Mach regime was characterised by a delayed and gradual shock wave development when compared to steady state, demonstrating a clear flow history effect. Deceleration through the transonic Mach regime was characterised by shock wave propagation from the base to the nose. New flow structures appeared during deceleration that do not have counterparts in the steady state, including shock interactions and propagating expansion-compression features. Gross changes in the unsteady drag coefficient curves for each cone-angle are explained with reference to unsteady shock wave behaviour for accelerating and decelerating motion.

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Section: Drag Coefficientmentioning

confidence: 53%

Section: Unsteadymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unsteady shock wave dynamics in accelerating and decelerating flight

et al. 2021

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“…al [15], Roohani et. al [16]. It was found that the unsteady flow field was significantly different from the steady state flow field at the same Mach number for subsonic and transonic flows.…”

Section: Introductionmentioning

confidence: 92%

Eulerian derivation of the conservation equation for energy in a non-inertial frame of reference in arbitrary motion

Musehane

Combrinck

Dala

2021

Applied Mathematics and Computation

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“…To date, theoretical investigations [3,4] have assumed that the detached SW is relatively close to the object, meaning that the speed range near Mach number 1 is yet to be B T. Kikuchi takamasa.kikuchi@gmail.com 1 College of Science and Technology, Nihon University, Narashinodai 7-24-1, Funabashi, Chiba 274-8501, Japan 2 Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba, Sendai, Miyagi 980-8577, Japan considered. Some numerical results have also been reported [5][6][7].…”

Section: Introductionmentioning

confidence: 92%

Measurement of unsteady shock standoff distance around spheres flying at Mach numbers near one

Kikuchi

Ohtani

2022

Shock Waves

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This paper reports the experiments on the shock standoff distance (SSD) around spheres flying at Mach numbers from slightly below 1.0. Spheres of the same diameter but three different densities were launched in a ballistic range by a light-gas gun, and the flow field around each sphere was measured by optical visualization. The purpose of this study is to investigate how projectile deceleration influences the SSD by comparing the results for projectiles of the same shape, size, and Mach number but different densities. The location history of the sphere center is obtained by fitting a formula derived from the equation of motion of a decelerating object, and the history of the instantaneous projectile Mach number is obtained by differentiating this formula.The SSDs of the projectiles with different densities are the same at higher Mach numbers, but different at lower Mach numbers, and the SSD decreases with decreasing projectile density. Seemingly, because projectile deceleration is related to the flow unsteadiness, steady flow cannot be assumed in the present range of Mach number with the different SSDs. At Mach numbers close to one, that of the propagating detached shock wave is higher than that of the flying projectile.

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Bow shock stand-off distance for subsonic decelerating bodies

Cited by 5 publications

References 27 publications

Unsteady shock wave dynamics in accelerating and decelerating flight

Unsteady shock wave dynamics in accelerating and decelerating flight

Eulerian derivation of the conservation equation for energy in a non-inertial frame of reference in arbitrary motion

Measurement of unsteady shock standoff distance around spheres flying at Mach numbers near one

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