Acoustic Perturbation Equations for Reacting Flows to Compute Combustion Noise

2007 ◽  
Vol 6 (4) ◽  
pp. 335-355 ◽  
Author(s):  
Thanh Phong Bui ◽  
Wolfgang Schröder ◽  
Matthias Meinke
Keyword(s):  
Reacting Flows ◽  
Combustion Noise ◽  
Acoustic Perturbation ◽  
Perturbation Equations

Efficient Three Dimensional Time-Domain Combustion Noise Simulation of a Premixed Flame Using Acoustic Perturbation Equations and Incompressible LES

2017 ◽  
Author(s):  
Kilian Lackhove ◽  
Amsini Sadiki ◽  
Johannes Janicka
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Combustion Noise ◽  
Governing Equations ◽  
Flow Solver ◽  
Acoustic Perturbation ◽  
Tabulated Chemistry ◽  
Combustion Systems ◽  
Perturbation Equations

Combustion noise has become a significant contributor to the overall noise emitted by modern aero-engines. This development is attributed to reduced noise sources in other components due to design improvements and the introduction of premixed combustors that burn more unsteadily and hence emit more noise. These next generation combustion systems are more prone to acoustic instabilities and thus require improved methods for the prediction of combustion noise. This paper presents a numerical approach which exploits the different scales prevalent in these combustion systems by computing the flow field and acoustics separately and coupling both simulations in real time. To demonstrate its capabilities, the methodology is successfully applied to a premixed and pressurized propane flame which was experimentally investigated by CNRS [1] and for which pressure measurement data are available. In the present numerical model, the separation of the physical phenomena facilitates the application of the most suitable numerical schemes and governing equations to both sets of problems. Due to the low Mach numbers governing typical combustors, the flow field can be adequately described by the incompressible Navier-Stokes equations. These are solved by an implicit finite volume flow solver which is supplemented by a tabulated chemistry approach to account for the combustion processes. For the acoustics, the three dimensional Acoustic Perturbation Equations (APE) are solved using a state of the art, low dispersion Discontinuous Galerkin CAA tool. Both codes are run in parallel and exchange fields on-line to maintain the highest possible temporal resolution and data transfer rates. The different natures of both phenomena require an elaborate coupling scheme that comprises temporal and spatial interpolation and filtering. Since the incompressible formulation of the flow solver allows for considerably larger time steps and the acoustics solver employs much simpler governing equations, the overall computational costs of this approach are up to 10 times lower than those of a compressible simulation with similar fidelity.

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 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.

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.

Acoustic perturbation equations and Lighthill’s acoustic analogy for the human phonation

2013 ◽  
Vol 133 (5) ◽  
pp. 3618-3618 ◽  
Author(s):  
Stefan Zoerner ◽  
Petr Šidlof ◽  
Andreas Hüppe ◽  
Manfred Kaltenbacher
Keyword(s):  
Acoustic Analogy ◽  
Acoustic Perturbation ◽  
Perturbation Equations
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