Resonant Oscillations Of Gas Research Articles

The Distributed Parameter Model of an Electro-Pneumatic System Actuated by Pneumatic Artificial Muscles with PWM-Based Position Control

Today, the analysis and synthesis methods of electro-pneumatic systems with position control actuated by pneumatic artificial muscles (PAMs) are quite well known. In these methods, pneumatic artificial muscle is considered as an object with lumped parameters. However, the PAM is an object with distributed parameters, where the pressure, density, and mass flow rate of gas are varied along the bladder length. Thus, in the case of certain design parameters of the pneumatic artificial muscle and certain frequencies of the supply pressure, resonant gas oscillations affected by the wave processes in the bladder may occur. Thereby, in the PWM-driven PAM-actuated system, certain operation frequencies of the control pneumatic valve can cause oscillations of gas in the bladder and in the connected pipeline. These processes could lead to vibrations of the executive device. To solve this practical problem, a distributed parameter model of the PAM that takes into account the pressure fluctuations in the bladder and in the pipeline was elaborated. Also, in this work, a new method in which the wave processes are described by ordinary differential equations instead of partial differential equations was proposed.

Effect of a Rigid Cone Inserted in a Tube on Resonant Gas Oscillations

Effect of a Rigid Cone Inserted in a Tube on Resonant Gas Oscillations

Resonant Gas Oscillations in a Closed Tube with a Coaxial Heat Source

Resonant Gas Oscillations in a Closed Tube with a Coaxial Heat Source

Nonlinear Resonant Gas Oscillations in Resonators with Variable Cross-section

Nonlinear Resonant Gas Oscillations in Resonators with Variable Cross-section

Resonant Oscillations of Gas in Tubes with Different Tips

Resonant Oscillations of Gas in Tubes with Different Tips

Effect of the Cone-Shaped End Vertex Angle of a Closed Tube on Resonant Gas Oscillations

Effect of the Cone-Shaped End Vertex Angle of a Closed Tube on Resonant Gas Oscillations

On the transition between continuous and shocked solutions for resonant gas oscillations in the frustum of a closed cone

Resonant gas oscillations in a closed straight tube contain shocks for frequencies near the linear resonant frequency. As the tube geometry changes from straight to a cone with slope $a,$ the shock strength decreases until, for large enough $a,$ the motion is continuous. The analytical result for small $a$ follows from a nonlinearization of the linear resonant response, while the result for large $a$ is a dominant single mode approximation. The connection between these two forms is analysed numerically. The shocked solutions change to multimode continuous solutions as $a$ increases to cross the curve $a_{s}\doteqdot 12.8M^{1/3}$ , where $M\ll 1$ is the Mach number of the input. Then the amplitudes of the higher modes decrease as $a$ continues to increase until, having crossed $a_{m}\doteqdot 30M^{1/3}$ , the single mode solution emerges.

Forced resonance gas oscillations in different cross-sections of a closed tube with a sudden change of the section diameter

Experimental results of forced gas oscillations in narrow and wide parts of a closed tube are presented. It was found that the gas pressure in the wide part of the tube close to the oscillator is higher than the pressure in the narrow part.

Analytical and experimental research of nonlinear resonant gas oscillations in a cube

The gas pressure in a cubic resonator is studied experimentally and numerically at the first resonant frequency. Lagrange’s approach is used to analytical study of problem. Comparison of the pressure oscillations obtained experimentally and numerically at different amplitudes of piston oscillation is carried out.

Distribution of the Heat Flux on the Axis in a Uniform Closed Tube with Highly Non-Linear Resonant Gas Oscillations

The results of an experimental study of the acoustothermal effect, which is large for nonlinear gas oscillations in a closed pipe at a resonant frequency, are presented. The distribution of the heat flow along the tube is obtained. It was found that at the ends of the closed tube, the heat flow takes maximum and positive values, which indicates the heating of the gas. In the middle of the tube, the gas takes on minimum values, which indicates cooling in this area.

Study of forced gas oscillations in a cube with a diaphragm near resonance

The results of studies of forced resonance gas oscillations in a cubic resonator are presented. It was found that the presence of a diaphragm in the resonator neck leads to an increase in the amplitude of gas pressure oscillations in the cube.

Resonant gas oscillation in a tube of square cross section

Nonlinear resonant gas oscillations in a tube of square cross section are studied by solving the full system of Navier-Stokes equations for three-dimensional compressible gas flows with a finite-difference method. The nonlinear gas oscillations with and without shock waves and resulting time-averaged transport phenomena of mass, momentum and energy are investigated in the tube of square cross section. In particular, we find that there exist streamlines of acoustic streaming visiting both the inside and outside of boundary layer, which means that the mass, momentum and energy transports are confined neither in the inside nor in the outside of boundary layer on the tube wall, contrary to two-dimensional flows.

Resonant oscillations of a gas in an open tube in the shock-free wave mode

Nonlinear gas oscillations excited in an open tube by a flat piston at one of the tube ends are studied. The sinusoidal piston oscillations in the shock-free wave mode are created by a vibration exciter near the first eigenfrequency. Expressions for gas pressure oscillations are obtained for a tube with a nonrounded end without a flange and secondary flow velocity components. The influence of the piston displacement amplitude on the pressure range and secondary flow velocity of gas is studied. The theoretical calculations of the gas pressure are compared with experimental data. An estimate for the velocity of particle motion along the tube axis is presented with calculated values of the secondary flow velocity.

Resonant Gas Oscillations in a Linear Area Variation Cavity: Rectangular Versus Circular Cross Section

Resonant gas oscillations in a linear area variation closed cavity are investigated, for two duct cross sections: rectangular and circular. The resonance frequencies were similar for both the ducts. Increased drive amplitude produced higher distortions in the waveform. It was found that both resonators exhibited commensurate behavior. This is opposed to noncommensurate behavior observed in nonuniform circular cross section resonators. The rectangular section duct had higher energy than circular section duct, in second harmonic for the same drive amplitude. The results reveal that in order to achieve shockless high amplitude pressure oscillations in a duct, both nonuniform area variation and circular cross section are required.

Asymptotic solutions for shocked resonant acoustic oscillations between concentric spheres and coaxial cylinders

For resonant oscillations of a gas in a straight tube with a closed end, shocks form and all harmonics are generated, see Chester [“Resonant oscillations in a closed tube,” J. Fluid Mech. 18, 44 (1964)]10.1017/S0022112064000040. When the gas is confined between two concentric spheres or coaxial cylinders, the radially symmetric resonant oscillations may be continuous or shocked. For a fixed small Mach number of the input, the flow is continuous for sufficiently small L, defined as the ratio of the inner radius to the difference of the radii, see Seymour et al. [“Resonant oscillations of an inhomogeneous gas between concentric spheres,” Proc. R. Soc. London, Ser. A 467, 2149 (2011)]10.1098/rspa.2010.0576. However, shocks appear in the resonant flow for either larger values of L or larger input Mach number. A nonlinear geometric acoustics approximation is used to analyse the shocked motion of the gas when L ≫ 1. This approximation and the exact numerical solution are compared for the shocked wave profiles a...

J054032 気液界面で相変化をともなう共鳴音波に関する分子気体力学解析([J05403]マイクロ・ナノスケールの熱流体現象(3))

J054032 気液界面で相変化をともなう共鳴音波に関する分子気体力学解析([J05403]マイクロ・ナノスケールの熱流体現象(3))

Computer simulation of the drift of solid particles caused by resonance gas oscillations in the open channel

Computer simulation methods are used to study the drift of solid spherical particles suspended in the open channel due to longitudinal oscillations of the gas column. The gas velocity field consists of periodic nonlinear waves and an acoustic flow. The particles move under the action of the Stokes force. Particle distributions in the wave field of the open channel are obtained in the vicinity of the first, second and third eigen-frequencies of the gas column. The particle’s spatial distribution features attributed to the particle’s drift under the action of acoustic radiation are revealed.

Nonlinear resonance gas oscillations in a flat open-ended channel

The resonance gas oscillations in a flat channel are considered; the oscillations are excited by a piston at the inlet and the outlet section is connected with the ambient medium. The boundary condition at the open end is calculated analytically; the dependences of the gas oscillation amplitude on the frequency and geometric parameters of the open end at different values of the frequency parameter are obtained.

Experimental and theoretical study of processes leading to steady-state sound in annular thermoacoustic engines

This paper gives a simplified analytical description of spontaneous generation and finite amplitude saturation of sound in annular thermoacoustic engines, and also provides comparison with experiments. The model includes the precise description of thermoacoustic amplification of sound (induced by interaction between an heterogeneously heated stack of solid plates and resonant gas oscillations), which accounts for the details of the temperature distribution in the whole thermoacoustic device (i.e., which does not only account for the mean temperature gradient along the stack). The saturation of the acoustic wave amplitude is described by taking into account both the reverse influence of high amplitude acoustic field on temperature field, and the dissipation of acoustic energy due to higher harmonics generation and minor losses (vortex generation). From the comparison between simulation results and experiments, it is demonstrated that the dynamical behavior observed in our experimental device is predominantly controlled by the effects of acoustic streaming and acoustically enhanced thermal conductivity tending not only to reduce the externally imposed temperature gradient along the stack, but also to change the shape of the temperature field.

Nonlinear resonant oscillations in closed tubes of variable cross-section

An axisymmetric tube with a variable cross-sectional area, closed at both ends, containing a polytropic gas is oscillated parallel to its axis at or near a resonant frequency. The resonant gas oscillations in an equivalent tube of constant cross-section contain shocks. We show how cone, horn and bulb resonators produce shockless periodic outputs. The output consists of a dominant fundamental mode, where its amplitude and detuning are connected by a cubic equation – the amplitude–frequency relation. For the same gas, a cone resonator exhibits a hardening behaviour, while a bulb resonator may exhibit a hardening or softening behaviour. These theoretical results agree qualitatively with available experimental results and are the basis for resonant macrosonic synthesis (RMS).