相关论文: Effects of Sound Suppressors on Muzzle Velocity, B…

We present experimental evidence that a bubble moving in a fluid in which a well-chosen acoustic noise is superimposed can be significantly slowed down for moderate acoustic pressures. Through mean velocity measurements, we show that a…

This paper describes the effects on aerodynamic drag of rifle bullets as the gyroscopic stability is lowered from 1.3 to 1.0. It is well known that a bullet can tumble for stability less than 1.0. The Sierra Loading Manuals (4th and 5th…

This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's…

Reconstruction of shooting events occasionally requires testing of bullets at velocities significantly below the typical muzzle velocity of cartridge arms. Trajectory, drag, and terminal performance depend strongly on velocity, and…

The ballistic coefficient of a bullet describes how it slows in flight due to air resistance. This article presents experimental determinations of ballistic coefficients showing that the majority of bullets tested have their previously…

The wolf note is an acoustic instability that occurs in large bowed string instruments when a strong body resonance interacts with the vibrating string, producing amplitude modulation and loss of tonal control. Various wolf suppressors -…

This article describes a simple method for using a PC soundcard to accurately measure bullet velocity. The method involves placing the microphone within a foot of the muzzle and firing at a steel target between 50 and 100 yards away. The…

It is known that listeners lose the ability to discriminate the direction of motion of a revolving sound (clockwise vs. counterclockwise) beyond a critical velocity ("the upper limit"), likely due to degraded front-back discrimination.…

Pure theory recognizes the dependence of supersonic drag coefficients on both Mach number and Reynolds number, which includes an implicit dependence of drag coefficient on air density. However, many modern approaches to computing…

Results of the measurements of sound speed and attenuation in a bubbly medium are reported. Monodisperse bubble solutions are sonicated with broadband ultrasound pulses with pressure amplitudes ranging between 12.5-100 kPa. Fundamental…

Landing-gear noise is an increasing issue for transport aircraft. A key determinant of the phenomenon is the surface pressure field. Previous studies have described this field when the oncoming flow is perfectly aligned with the gear. In…

Drag reduction in stationary turbulent flows by bubbles is sensitive to the dynamics of bubble oscillations. Without this dynamical effect the bubbles only renormalize the fluid density and viscosity, an effect that by itself can only lead…

Experiments on the oscillatory motion of a suspended bar magnet throws light on the damping effects acting on the pendulum. The viscous drag offered by air was found the be the main contributor for slowing the pendulum down. The nature and…

Sound production due to turbulence is widely shown to be an important phenomenon involved in a.o. fricatives, singing, whispering and speech pathologies. In spite of its relevance turbulent flow is not considered in classical physical…

Sound propagation in superfluid $^3$He in aerogel is studied on the basis of a two-fluid model taking into account the effect by the drag force due to collisions between $^3$He-quasiparticles and aerogel molecules. The drag force plays a…

The flow of fluids in channels, pipes or ducts, as in any other wall-bounded flow (like water along the hulls of ships or air on airplanes) is hindered by a drag, which increases many-folds when the fluid flow turns from laminar to…

Dielectric fluids experience a striction force in the presence of an external electric field. Although the striction force on the entire body of the fluid is usually zero, it does contribute to its deformations. In this paper, I show that…

Acoustic material parameters of gas hydrate bearing porous rocks are important for evaluation of methods to exploit the vast methane gas resources present in the earth's subsurface, potentially combined with CO2 injection. A solid buffer…

The main motivation of the current study is to propose a high-pressure hydrogen injection as an hybrid active flow control technique in order to manipulate the flow-field in front of a blunt nose during hypersonic flight. Hydrogen injection…

We report on the modification of drag by neutrally buoyant spherical particles in highly turbulent Taylor-Couette flow. These particles can be used to disentangle the effects of size, deformability, and volume fraction on the drag, when…