scholarly journals Звуковой удар от тонкого тела и локальных областей нагрева сверхзвукового набегающего потока

2021 ◽  
Vol 91 (4) ◽  
pp. 558
Author(s):  
А.В. Потапкин ◽  
Д.Ю. Москвичев
Keyword(s):  
Mach Number ◽  
Supersonic Flow ◽  
Free Stream ◽  
Local Heating ◽  
Air Flow ◽  
Sonic Boom ◽  
Incoming Flow ◽  
Combined Method ◽  
Cold Flow ◽  
Free Stream Mach Number

The problem of a sonic boom generated by a slender body and local regions of supersonic flow heating is solved numerically. The free-stream Mach number of the air flow is 2. The calculations are performed by a combined method of phantom bodies. The results show that local heating of the incoming flow can ensure sonic boom mitigation. The sonic boom level depends on the number of local regions of incoming flow heating. One region of flow heating can reduce the sonic boom by 20% as compared to the sonic boom level in the cold flow. Moreover, consecutive heating of the incoming flow in two regions provides sonic boom reduction by more than 30%.

scholarly journals Снижение уровня звукового удара с помощью разогрева набегающего потока

2019 ◽  
Vol 45 (10) ◽  
pp. 42
Author(s):  
А.В. Потапкин ◽  
Д.Ю. Москвичев
Keyword(s):  
Mach Number ◽  
Local Heating ◽  
Air Flow ◽  
The Body ◽  
Sonic Boom ◽  
Combined Method ◽  
Incident Flow ◽  
Cold Air ◽  
Cold Flow ◽  
Thermal Wake

The level of the sonic boom arising due to local heating of the air flow ahead of a slender body flying at a supersonic velocity in the thermal wake behind the heating regions is calculated. The Mach number of the cold air flow is 2. The calculations are performed by a combined method of “phantom bodies.” It is demonstrated that consecutive local heating of the incident flow in two regions ahead of the body ensures reduction of the sonic boom level by more than 30% as compared to the sonic boom generated by the body in the cold flow.

scholarly journals Влияние локального нагрева набегающего потока на уровень звукового удара от тонкого тела, находящегося в аэродинамической тени за диском

2021 ◽  
Vol 47 (16) ◽  
pp. 28
Author(s):  
А.В. Потапкин ◽  
Д.Ю. Москвичев
Keyword(s):  
Mach Number ◽  
Local Heating ◽  
Air Flow ◽  
Sonic Boom ◽  
Thin Body ◽  
Body Of Revolution ◽  
Combined Method ◽  
Incident Flow ◽  
Heating Region ◽  
Two Bodies

Calculations are performed for a sonic boom generated by two bodies (a disk and a thin body of revolution) in the case of local heating of the incident air flow. The bodies are in a heat trail behind the heating region. The thin body is in an aerodynamic shadow behind the disk. The Mach number of the cold air flow is 2. The calculations are carried out using the combined method of "phantom bodies". It is concluded on the basis of the calculations that the level of a sonic boom can be effectively suppressed by simultaneously using the heating of the incident flow and the aerodynamic shadow behind the disk.

Experimental Investigation of Self-Sustained Oscillations on the Spike-Tipped Cylinder in Supersonic Flow

2005 ◽  
Vol 4 (3) ◽  
pp. 363-372 ◽  
Author(s):  
V.I. Zapryagaev ◽  
I.N. Kavun
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Supersonic Flow ◽  
Free Stream ◽  
Cone Angle ◽  
The Self ◽  
Flow Mode ◽  
Periodic Flows ◽  
Sustained Oscillations ◽  
Free Stream Mach Number

A study of the self-sustained quasi-periodic flows near the spike-tipped body at free-stream Mach number M∞ = 6 is carried out. The influence of length and spike cone angle on a flow structure is shown. The character of the pulsation flow mode depending on the geometry of the model is defined.

Controlling the sonic boom from a thin body by means of local heating of the incoming flow

Shock Waves ◽  
2013 ◽  
Vol 23 (6) ◽  
pp. 649-658 ◽  
Author(s):  
A. V. Potapkin ◽  
D. Yu. Moskvichev
Keyword(s):  
Local Heating ◽  
Sonic Boom ◽  
Thin Body ◽  
Incoming Flow

Direct numerical simulation of flow past a transversely rotating sphere up to a Reynolds number of 300 in compressible flow

2018 ◽  
Vol 857 ◽  
pp. 878-906 ◽  
Author(s):  
T. Nagata ◽  
T. Nonomura ◽  
S. Takahashi ◽  
Y. Mizuno ◽  
K. Fukuda
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Mach Number ◽  
Direct Numerical Simulation ◽  
Drag Coefficient ◽  
Rotation Rate ◽  
Free Stream ◽  
Rotating Sphere ◽  
Free Stream Mach Number ◽  
Low Reynolds

In this study, direct numerical simulation of the flow around a rotating sphere at high Mach and low Reynolds numbers is conducted to investigate the effects of rotation rate and Mach number upon aerodynamic force coefficients and wake structures. The simulation is carried out by solving the three-dimensional compressible Navier–Stokes equations. A free-stream Reynolds number (based on the free-stream velocity, density and viscosity coefficient and the diameter of the sphere) is set to be between 100 and 300, the free-stream Mach number is set to be between 0.2 and 2.0, and the dimensionless rotation rate defined by the ratio of the free-stream and surface velocities above the equator is set between 0.0 and 1.0. Thus, we have clarified the following points: (1) as free-stream Mach number increased, the increment of the lift coefficient due to rotation was reduced; (2) under subsonic conditions, the drag coefficient increased with increase of the rotation rate, whereas under supersonic conditions, the increment of the drag coefficient was reduced with increasing Mach number; and (3) the mode of the wake structure becomes low-Reynolds-number-like as the Mach number is increased.

Subsonic Flow Over Open Cavities: Part 1 — Analytical Models and Numerical Investigations

2016 ◽  
Author(s):  
Weidong Shao ◽  
Jun Li
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Shear Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Feedback Loop ◽  
Subsonic Flow ◽  
Free Stream ◽  
Open Cavities ◽  
Free Stream Mach Number

The aeroacoustical oscillation and acoustic field generated by subsonic flow grazing over open cavities has been investigated analytically and numerically. The tone generation mechanism is elucidated with an analytical model based on the coupling between shear layer instabilities and acoustic feedback loop. The near field turbulent flow is obtained using two-dimensional Large Eddy Simulation (LES). A special mesh is used to absorb propagating disturbances and prevent spurious numerical reflections. Comparisons with available experimental data demonstrate good agreement in both the frequency and amplitude of the aeroacoustical oscillation. The physical phenomenon of the noise generated by the feedback loop is discussed. The correlation analysis of primitive variables is also made to clarify the characteristics of wave propagation in space and time. The effects of free-stream Mach number and boundary layer thickness on pressure fluctuations within the cavity and the nature of the noise radiated to the far field are examined in detail. As free-stream Mach number increases velocity fluctuations and mass flux into the cavity increase, but the resonant Strouhal numbers slightly decrease. Both the resonant Strouhal numbers and sound pressure levels decrease with the increase of boundary layer thickness. Results indicate that the instability of the shear layer dominates both the frequency and amplitude of the aeroacoustical oscillation.

Second-order boundary-layer effects in hypersonic flow past axisymmetric blunt bodies

1964 ◽  
Vol 20 (4) ◽  
pp. 593-623 ◽  
Author(s):  
R. T. Davis ◽  
I. Flügge-Lotz
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Free Stream ◽  
Practical Interest ◽  
Second Order ◽  
The Body ◽  
Specific Flow ◽  
Flow Past ◽  
Free Stream Mach Number ◽  
Stability And Accuracy

First- and second-order boundary-layer theory are examined in detail for some specific flow cases of practical interest. These cases are for flows over blunt axisymmetric bodies in hypersonic high-altitude (or low density) flow where second-order boundary-layer quantities may become important. These cases consist of flow over a hyperboloid and a paraboloid both with free-stream Mach number infinity and flow over a sphere at free-stream Mach number 10. The method employed in finding the solutions is an implicit finite-difference scheme. It is found to exhibit both stability and accuracy in the examples computed. The method consists of starting near the stagnation-point of a blunt body and marching downstream along the body surface. Several interesting properties of the boundary layer are pointed out, such as the nature of some second-order boundary-layer quantities far downstream in the flow past a sphere and the effect of strong vorticity interaction on the second-order boundary layer in the flow past a hyperboloid. In several of the flow cases, results are compared with other theories and experiments.

Sign in / Sign up

Export Citation Format

Share Document