scholarly journals A Lagrangian Approach for Computational Acoustics with Meshfree Method

2017 ◽  
Author(s):  
Yong Ou Zhang ◽  
Stefan G. Llewellyn Smith ◽  
Tao Zhang ◽  
Tian Yun Li
Keyword(s):  
Sound Propagation ◽  
Fluid Dynamic ◽  
Taylor Series Expansion ◽  
Meshfree Method ◽  
Lagrangian Approach ◽  
Meshfree Methods ◽  
Combustion Noise ◽  
Smoothed Particle ◽  
The Time Domain ◽  
Perturbation Equations

Although Eulerian approaches are standard in computational acoustics, they are less effective for certain classes of problems like bubble acoustics and combustion noise. A different approach for solving acoustic problems is to compute with individual particles following particle motion. In this paper, a Lagrangian approach to model sound propagation in moving fluid is presented and implemented numerically, using three meshfree methods to solve the Lagrangian acoustic perturbation equations (LAPE) in the time domain. The LAPE split the fluid dynamic equations into a set of hydrodynamic equations for the motion of fluid particles and perturbation equations for the acoustic quantities corresponding to each fluid particle. Then, three meshfree methods, the smoothed particle hydrodynamics (SPH) method, the corrective smoothed particle (CSP) method, and the generalized finite difference (GFD) method, are introduced to solve the LAPE and the linearized LAPE (LLAPE). The SPH and CSP methods are widely used meshfree methods, while the GFD method based on the Taylor series expansion can be easily extended to higher orders. Applications to modeling sound propagation in steady or unsteady fluids in motion are outlined, treating a number of different cases in one and two space dimensions. A comparison of the LAPE and the LLAPE using the three meshfree methods is also presented. The Lagrangian approach shows good agreement with exact solutions. The comparison indicates that the CSP and GFD method exhibit convergence in cases with different background flow. The GFD method is more accurate, while the CSP method can handle higher Courant numbers.

scholarly journals Broadband Combustion Noise Simulation of the PRECCINSTA Burner Based on Stochastic Sound Sources

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Felix Grimm ◽  
Duncan Ohno ◽  
Berthold Noll ◽  
Manfred Aigner ◽  
Roland Ewert ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Sound Propagation ◽  
Particle Method ◽  
Combustion Noise ◽  
Navier Stokes ◽  
Noise Prediction ◽  
Sound Sources ◽  
Linearized Euler Equations ◽  
Industrial Gas Turbines ◽  
The Time Domain

Combustion noise in the laboratory scale PRECCINSTA (prediction and control of combustion instabilities in industrial gas turbines) burner is simulated with a new, robust, and highly efficient approach for combustion noise prediction. The applied hybrid method FRPM-CN (fast-random particle method for combustion noise prediction) relies on a stochastic, particle-based sound source reconstruction approach. Turbulence statistics from reacting CFD-RANS (computational fluid dynamics–Reynolds-Averaged Navier–Stokes) simulations are used as input for the stochastic method, where turbulence is synthesized based on a first-order Langevin ansatz. Sound propagation is modeled in the time domain with a modified set of linearized Euler equations and monopole sound sources are incorporated as right-hand side forcing of the pressure equation at every timestep of the acoustics simulations. First, the reacting steady-state CFD simulations are compared to experimental data, showing very good agreement. Subsequently, the computational combustion acoustics (CCA) setup is introduced, followed by comparisons of numerical with experimental pressure spectra. It is shown that FRPM-CN accurately captures absolute combustion noise levels without any artificial correction. Benchmark runs show that the computational costs of FRPM-CN are much lower than that of direct simulation approaches. The robustness and reliability of the method is demonstrated with parametric studies regarding source grid refinement, the choice of either RANS or URANS statistics, and the employment of different global reaction mechanisms.

Broadband Combustion Noise Simulation of the PRECCINSTA Burner Based on Stochastic Sound Sources

2016 ◽  
Author(s):  
Felix Grimm ◽  
Duncan Ohno ◽  
Roland Ewert ◽  
Jürgen Dierke ◽  
Berthold Noll ◽  
...  
Keyword(s):  
Sound Propagation ◽  
Particle Method ◽  
Combustion Noise ◽  
Noise Prediction ◽  
Sound Sources ◽  
Linearized Euler Equations ◽  
Noise Simulation ◽  
Parametric Studies ◽  
Global Reaction ◽  
The Time Domain

Combustion noise in the laboratory scale PRECCINSTA burner is simulated with a new, robust and highly efficient approach for combustion noise prediction. The applied hybrid method FRPM-CN (Fast Random Particle Method for Combustion Noise prediction) relies on a stochastic, particle based sound source reconstruction approach. Turbulence statistics from reacting CFD-RANS simulations are used as input for the stochastic method, where turbulence is synthesized based on a first order Langevin ansatz. Sound propagation is modeled in the time domain with a modified set of linearized Euler equations and monopole sound sources are incorporated as right hand side forcing of the pressure equation at every timestep of the acoustics simulations. First, reacting steady state CFD simulations are compared to experimental data, showing very good agreement. Subsequently, the computational combustion acoustics setup is introduced, followed by comparisons of numerical with experimental pressure spectra. It is shown that FRPM-CN accurately captures absolute combustion noise levels without any artificial correction. Benchmark runs show that the computational costs of FRPM-CN are much lower than that of direct simulation approaches. The robustness and reliability of the method is demonstrated with parametric studies regarding source grid refinement, the choice of either RANS or URANS statistics and the employment of different global reaction mechanisms.

?Smoothed particle hydrodynamics ? a meshfree method?

2004 ◽  
Vol 33 (6) ◽  
pp. 491-491 ◽  
Author(s):  
M. B. Liu ◽  
G. R. Liu ◽  
Shaofan Li
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Meshfree Method ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

High Amplitude Sound Propagation at Low Frequencies in a Flow Duct Lined With Resonators: A Time Domain Solution

1988 ◽  
Vol 110 (4) ◽  
pp. 545-551 ◽  
Author(s):  
A. Cummings ◽  
I.-J. Chang
Keyword(s):  
Time Domain ◽  
Internal Combustion Engines ◽  
Sound Propagation ◽  
Sound Field ◽  
High Amplitude ◽  
Combustion Engines ◽  
Low Frequencies ◽  
The Time Domain ◽  
Flow Duct ◽  
Good Agreement

A quasi one-dimensional analysis of sound transmission in a flow duct lined with an array of nonlinear resonators is described. The solution to the equations describing the sound field and the hydrodynamic flow in the neighborhood of the resonator orifices is performed numerically in the time domain, with the object of properly accounting for the nonlinear interaction between the acoustic field and the resonators. Experimental data are compared to numerical computations in the time domain and generally very good agreement is noted. The method described here may readily be extended for use in the design of exhaust mufflers for internal combustion engines.

scholarly journals Prediction of flow-control devices' noise with modified acoustic perturbation equations

2020 ◽  
Vol 22 (3) ◽  
pp. 619-627
Author(s):  
Luca Fenini ◽  
Stefano Malavasi
Keyword(s):  
Flow Control ◽  
Fluid Dynamic ◽  
International Standards ◽  
The Other ◽  
Computational Time ◽  
Noise Prediction ◽  
Acoustic Perturbation ◽  
Flow Control Devices ◽  
Control Devices ◽  
Perturbation Equations

Abstract Fluid-dynamic noise emissions produced by flow-control devices inside ducts are a concerning issue for valve manufacturers and pipeline management. This work proposes a modified formulation of Acoustic Perturbation Equations (APE) that is applicable to industrial frameworks where the interest is addressed to noise prediction according to international standards. This formulation is derived from a literature APE system removing two terms allowing for a computational time reduction of about 20%. The physical contribution of the removed terms is discussed according to the literature. The modified APE are applied to the prediction of the noise emitted by an orifice. The reliability of the new APE system is evaluated by comparing the Sound Pressure Level (SPL) and the acoustic pressure with the ones returned by LES and literature APE. The new formulation agrees with the other methods far from the orifice: moving over nine diameters downstream of the trailing edge, the SPL is in accordance with the other models. Since international standards characterize control devices with the noise measured 1 m downstream of them, the modified APE formulation provides reliable and faster noise prediction for those devices with outlet diameter, d, such that 9d < 1 m.

Dynamic Analysis of Fracture in Thin-Walled Pipes

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
C. Gato ◽  
Y. Shie
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Fracture ◽  
Meshfree Method ◽  
Meshfree Methods ◽  
Shape Functions ◽  
Order Continuity ◽  
Cylindrical Structures ◽  
Thin Walled Structures ◽  
Ill Conditioning ◽  
Thin Walled

Dynamic fracture of thin-walled cylindrical structures is studied with a large deformation meshfree method. Due to the higher order continuity and smoothness of the shape functions, meshfree methods are well suited to simulate dynamic fracture of thin-walled structures since they avoid ill-conditioning as well as stiffening in numerical computations. Simulations of detonation driven fracture in thin pipes demonstrate the efficiency of the method.

Numerical Simulation of Broadband Combustion Noise With the RPM-CN Approach

2009 ◽  
Author(s):  
B. Mu¨hlbauer ◽  
R. Ewert ◽  
O. Kornow ◽  
B. Noll ◽  
M. Aigner
Keyword(s):  
High Efficiency ◽  
Numerical Approach ◽  
Combustion Noise ◽  
Acoustic Measurements ◽  
Noise Sources ◽  
Computational Costs ◽  
Acoustic Perturbation ◽  
Simulation Results ◽  
The Time Domain ◽  
Good Agreement

A new numerical approach called RPM-CN approach is applied to predict broadband combustion noise. This highly efficient hybrid CFD/CAA approach can rely on a reactive RANS simulation. The RPM method is used to reconstruct stochastic broadband combustion noise sources in the time domain based on statistical turbulence quantities. Subsequently, the propagation of the combustion noise is computed by solving the acoustic perturbation equations (APE-4). The accuracy of the RPM-CN approach will be demonstrated by a good agreement of the simulation results with acoustic measurements of the DLR-A flame. The high efficiency and therefore low computational costs enable the usage of this numerical approach in the design process.

An Approximate Three-Dimensional Aerodynamic Design Method for Centrifugal Impeller Blades

1990 ◽  
Vol 112 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Zhao Xiaolu ◽  
Qin Lisen
Keyword(s):  
Centrifugal Compressor ◽  
Design Method ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Design Procedure ◽  
Taylor Series Expansion ◽  
Centrifugal Impeller ◽  
Aerodynamic Design ◽  
Impeller Blade ◽  
Blade Geometry

An aerodynamic design method, which is based on the Mean Stream Surface Method (MSSM), has been developed for designing centrifugal compressor impeller blades. As a component of a CAD system for centrifugal compressor, it is convenient to use the presented method for generating impeller blade geometry, taking care of manufacturing as well as aerodynamic aspects. The design procedure starts with an S2m indirect solution. Afterward from the specified S2m surface, by the use of Taylor series expansion, the blade geometry is generated by straight-line elements to meet the manufacturing requirements. Simultaneously, the fluid dynamic quantities across the blade passage can be determined directly. In terms of these results, the designer can revise the distribution of angular momentum along the shroud and hub, which are associated with blade loading, to get satisfactory velocities along the blade surfaces in order to avoid or delay flow separation.

Efficient Combustion Noise Simulation of a Gas Turbine Model Combustor Based on Stochastic Sound Sources

2015 ◽  
Author(s):  
Felix Grimm ◽  
Roland Ewert ◽  
Jürgen Dierke ◽  
Gilles Reichling ◽  
Berthold Noll ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Sound Source ◽  
Sound Propagation ◽  
Hybrid Approach ◽  
Particle Method ◽  
Combustion Noise ◽  
Equation Modeling ◽  
Source Modeling ◽  
Sound Sources ◽  
Turbine Model

A gas turbine model combustor is simulated with a hybrid, stochastic and particle-based method for combustion noise prediction with full 3D sound source modeling and sound propagation. Alongside, an incompressible LES simulation of the burner is considered for the investigation of the performance of the hybrid approach. The highly efficient time-domain method consists of a stochastic sound source reconstruction algorithm, the Fast Random Particle Method (FRPM) and sound wave propagation via Linearized Euler Equations (LEEs). In the context of this work, the method is adapted and tested for Combustion Noise (CN) prediction. Monopole sound sources are reconstructed by using an estimation of turbulence statistics from reacting CFD-RANS simulations. First, steady state and unsteady CFD calculations of flow field and combustion of the model combustor are evaluated and compared to experimental results. Two equation modeling for turbulence and the EDM (Eddy Dissipation Model) with FRC (Finite Rate Chemistry) for combustion are employed. In a second step, the acoustics simulation setup for the model combustor is introduced. Selected results are presented and FRPM-CN pressure spectra are compared to experimental levels.

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