The numerical simulation of compressible jet at low Reynolds number using OpenFOAM

Abstract

The paper presents an analysis of various approaches for calculation gas-dynamic parameters and acoustic perturbations generated by a compressible jet at low Reynolds number (M = 0.9, Re = 3600). The jet flow parameters at selected conditions are well studied and can be used for validation of the numerical methods and schemes. The OpenFOAM software package with various approaches (solvers) such as pimpleCentralFoam, dbnsTurbFoam and new QGDFoam solver based on QGD-algorithms are considered. The results of time-averaged flow parameters and acoustic properties are compared with the experimental data. To determine the acoustic perturbation the Ffowcs Williams and Hawkings analogy implemented in our OpenFOAM library (libAcoustic) has been used.

Study of the Hershel-Quinke Resonator

“…But it can be expanded if near the frequency f 0 = f 2 there is one more resonant frequency f 1 of the type II resonances. Moreover, according to (9), Also, as follows from (12) and (13), the relation f 1 < f 2 always holds. It should be also be borne in mind that the next resonant frequency for the second type resonance f 3 = 2f 1 .…”

“…It should be noted that today numerical methods are increasingly used in in calculating mufflers and other areas of applied acoustics [7][8][9][10][11][12]. To analyze the acoustic characteristics of the Herschel-Quincke pipe, a numerical calculation method based on finite element modeling was applied.…”

“…If we now bring the frequencies f 1 and f 2 , closer together, then the damping band in the vicinity of these frequencies will decrease Δf, and the damping level ΔL will increase. Introducing the designation h = f 2 /f 1 , from (12) and (13) we obtain expressions that determine the length of the resonator tubes in which these lengths are inversely proportional to the frequency f 2 = f 0 . Hence it follows that the ratio of the lengths of the resonator tubes so that for h → 1 we get l 3 /l 2 → 3, and for h → 1,5 we get l 3 /l 2 → 2 Using formulas (14) and (15), for a given parameter h, the corresponding the tube lengths l 3 and l 2 were determined, and then were calculated for the obtained configuration of the resonator its transmission loss.…”

Locomotive Noise Reduction

“…To determine the required parameters, the noise barrier was modeled using finite element modeling in COMSOL Multiphysics. Such an approach in recent times is increasingly used [7][8][9][10][11]. This modeling method allows presenting a discrete space as a finite set of elementary volumes.…”

Acoustic Characteristics of Noise Absorbing Barriers

“…And although it is very difficult to take these factors into account when calculating by analytical methods, much attention continues to be paid to the development of these methods [4][5][6][7][8][9][10][11][12][13][14]. At the same time, it should be borne in mind that in the near future, numerical methods will become the main tool in calculating acoustic barriers and other areas of applied acoustics [15][16][17][18][19]. According to [15], using finite element modeling, the features of the formation of an acoustic pattern in the vicinity of the barrier located on the underlying surface are studied and the laws of the influence of this surface on the acoustic efficiency of the barrier are analyzed.…”