Features of separated supersonic flow pulsations ahead of a spike-tipped cylinder

Zapryagaev, V. I.; Mironov, S. G.

doi:10.1007/bf00850639

Cited by 15 publications

(16 citation statements)

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“…The points on the oscillogram correspond to times when the displayed photographs were taken. At M ∞ = 6, the mechanism of self-sustained pulsations observed is consistent with the mechanism of self-sustained pulsations at M ∞ = 2 [4]. The photographs corresponding to the time interval 0 τ 0.4 show the motion of the bow shock wave W 1 toward the frontal face of the cylinder.…”

supporting

confidence: 77%

“…This problem has been studied in many experimental and theoretical investigations (see, e.g., [2][3][4][5][6]). The physical pattern of such a flow, however, has not been adequately addressed, which necessitates further research.…”

Section: Introductionmentioning

confidence: 99%

“…According to [4,6], the main reason for origination of a pulsating flow regime is the formation of an annular supersonic jet J (Fig. 1c) at the point T of intersection of the conical shock wave W c and the bow shock wave W 1 .…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism of mass-flow oscillations is described in more detail for a free-stream Mach number M ∞ = 2 in [4]. It was believed before now that gas viscosity exerts a significant effect on the characteristics of an unsteady pulsating process.…”

mentioning

confidence: 99%

“…After this phase of pulsations is completed, a new separation zone bounded by a conical shock wave appears, and the entire process is periodically repeated. Such a flow regime, which was first discovered by Mair (see [1]), is considered in the present paper.This problem has been studied in many experimental and theoretical investigations (see, e.g., [2][3][4][5][6]). The physical pattern of such a flow, however, has not been adequately addressed, which necessitates further research.…”

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confidence: 99%

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Experimental study of the reverse flow in the forward separation region in a pulsating flow around a spiked body

Zapryagaev

Kavun

2007

J Appl Mech Tech Phys

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UDC 534.13:533.6.011.5 V. I. Zapryagaev and I. N. KavunThe flow with a free-stream Mach number M ∞ = 6 around a cylindrical body with a sharp spike is studied. The existence of a supersonic reverse flow for one of the phases of the pulsating flow regime is experimentally validated. A range of spike lengths is determined, which ensures a region of a supersonic reverse flow near the side surface of the spike. The time of existence of the supersonic reverse flow region is shown to be 0.15 of the period of pulsations if the spike length equals the model diameter. Introduction.A supersonic gas flow around a spiked blunt body is accompanied by the emergence of a flow with a forward separation region. At certain geometric and gas-dynamic parameters, there arises a periodic self-oscillatory flow. Two types of such a flow are distinguished, depending on the spike length. In the oscillatory flow regime, the conical shock wave bounding the separation region performs small periodic transverse oscillations. The shape of the wave remains essentially unchanged. Figures 1a and 1b show the flow structures for two typical phases of oscillations.As the spike length is reduced, the amplitude of oscillations increases, and a certain value of the amplitude gives rise to the pulsating flow regime. At this moment, the shape of the separation region becomes essentially different. Typical structures of the flow for two phases are shown in Figs. 1c and 1d. As the pulsating process evolves, the volume of the separation region increases, the conical wave transforms to a hemispherical one, and then the separation region disappears because the flow rate of the gas escaping from the separation region is significantly greater than the flow rate of the incoming gas. After this phase of pulsations is completed, a new separation zone bounded by a conical shock wave appears, and the entire process is periodically repeated. Such a flow regime, which was first discovered by Mair (see [1]), is considered in the present paper.This problem has been studied in many experimental and theoretical investigations (see, e.g., [2][3][4][5][6]). The physical pattern of such a flow, however, has not been adequately addressed, which necessitates further research.According to [4,6], the main reason for origination of a pulsating flow regime is the formation of an annular supersonic jet J (Fig. 1c) at the point T of intersection of the conical shock wave W c and the bow shock wave W 1 . The mechanism responsible for the emergence of a pulsating flow is as follows. A high-velocity gas flow behind a weak shock wave W c moves in the form of an annular jet J in the region between this wave and the separation-region boundary toward the body on which this flow is impinging. Because of jet curving toward the model centerline, the gas predominantly enters the separation region. The size of this region increases, which converts the conical shock wave W c into the detached curved shock wave W 1 . At a certain stage of development of the pulsating process, the increase in the r...

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confidence: 77%