Validation of a Model for Open Rotor Noise Predictions and Calculation of Shielding Effects using a Fast BEM

Lummer, Markus; Richter, Christoph; Pröber, Carsten; Delfs, Jan

doi:10.2514/6.2013-2096

Cited by 24 publications

(19 citation statements)

References 18 publications

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“…This approach was successfully applied to Contra Rotating Open Rotors (CROR) (where there is a complex interaction between the two propellers) in frequency domain, coupled with a fast-multipole boundary element method (FM-BEM). 3 In contrast to the method used by Lummer at al., 3 the point sources are realized in the finite-differences CAA code PIANO in the time domain enabling also the consideration of inhomogeneous meanflow. This implementation is validated against an analytic solution for simple cases.…”

Section: Introductionmentioning

confidence: 90%

Installation Effects of a Propeller Mounted on a Wing with Coanda Flap. Part II: Numerical Investigation and Experimental Validation

Dierke

Akkermans

Delfs

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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Within the framework of the German project "Bürgernahes Flugzeug" (Citizen Friendly Aircraft), we are investigating the effect of installation on propeller sound. A nine-bladed propeller installed in front of a wing equipped with a Coanda flap is considered. This configuration produces significant high lift and thereby considerably influences the inflow condition of the propeller. The sound generated by the propeller is furthermore shielded by and reflected off the wing. In this contribution, we present an implementation of an acoustic propeller model in a finite differences CAA (computational aeroacoustics) code. Comparisons of isolated propeller computations in a quiescent flow with an analytical model illustrate the correct numerical implementation. The verification of the implementation is presented for an example of an isolated propeller. A comparison for the installed propeller with experiments is conducted for different settings.

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Section: Introductionmentioning

confidence: 90%

Installation Effects of a Propeller Mounted on a Wing with Coanda Flap. Part II: Numerical Investigation and Experimental Validation

Dierke

Akkermans

Delfs

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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“…Thus, using the transfer function the far-field signature near point a can be transformed into a nearfield signature near point c. The partial sum A a (x) near c can then be calculated by integration over the unit sphere using eqn. (33). The signature functions are represented by their values given at collocation pointsŝ i j on the unit sphere, where, e. g., i represents an azimutal position and j a polar position.…”

Section: Fast Multipole Methods (Fmm)mentioning

confidence: 99%

“…A numerically efficient implementation of the ML-FMM is quite complex and it is not possible to go into the details here. Since the DLR Code FMCAS is an almost standard implementation it is possible to refer to the literature, e. g., [44,54,53,33], and to mention only some points where special techniques have been found advantageous. First, the iterative solvers from the 'Portable, Extensible Toolkit for Scientific Computation' (PETSc) were used [6,5,7].…”

Section: Implementation Of the Fmmmentioning

confidence: 99%

Installation: numerical investigation

Lummer

2019

CEAS Aeronaut J

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Acoustic installation effects are considered as scattering problem. Two methods to investigate them are presented. First, a Fast Multipole Method Boundary Element Method (FMM-BEM) which can solve the Helmholtz wave equation for full scale aircraft configurations at frequencies of some kHz. There, low Mach number potential mean flow fields can be taken into account by a so-called Taylor transformation. Second, a Discontinuous Galerkin Method (DGM) which solves Acoustic Perturbation Equations (APE) for realistic mean flow fields is presented. DGM calculations are very expensive and can be performed for full scale aircrafts only at low frequencies. Its main purpose so far is to assess the accuracy of the FMM for selected cases. The Taylor transformed Helmholtz equation is derived and the fundamentals of the FMM are introduced. Some details of the DLR FMM code FMCAS are given. The basic DGM equations are derived for the APE and some implementation details of the DLR DGM code DISCO++ are discussed. For generic geometries results of the FMM and DGM are compared and the limits of the Taylor transfor

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“…However, given the gross simplifications of the aircraft geometry used in these models, their accuracy is somewhat questionable. Fortunately, it is possible to accurately calculate scattering numerically using schemes such as those described by Le Garrec and Reboul (49) and also Lummer et al (50) . (63) .…”

Section: Installation Effectsmentioning

confidence: 99%

Advanced open rotor noise prediction

Kingan

2014

Aeronaut. j. (1968)

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The purpose of this paper is to describe the current status of open rotor noise prediction methods and to highlight future challenges in this area. A number of analytic and numerical methods are described which can be used for predicting 'isolated' and 'installed' open rotor tonal noise. Broadband noise prediction methods are also described and it is noted that further development and validation of the current models is required. The paper concludes with a discussion of the analytical methods which are used to assess the acoustic data collected during the high-speed wind-tunnel testing of a model scale advanced open rotor rig. IntroductIonThe advanced open rotor offers potentially significant reductions in fuel burn relative to current generation turbo-fan engines. Because of this significant benefit, the open rotor is currently being investigated by a number of leading aeronautical companies as a potential aircraft propulsor. A cut-away view of an open rotor concept is shown in Fig. 1 below. The engine consists of two contra-rotating rotors which, in this case, are driven by a gas turbine engine housed within a large centrebody which protrudes both fore and aft of the rotors. In order to be a viable aircraft engine, the open rotor will need to meet stringent noise certification standards and thus, a range of prediction methods are required for assessing the noise produced by various open rotor designs. These range from simple analytical methods, which are useful for design optimisation studies e.g. Parry and Vianello (1) , to high-fidelity CFD/CAA methods which are useful for design validation e.g. Colin et al. (2) . The purpose of this paper is to describe a range of noise prediction methods and, in particular, to highlight recent developments and to identify further work which is required.

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Validation of a Model for Open Rotor Noise Predictions and Calculation of Shielding Effects using a Fast BEM

Cited by 24 publications

References 18 publications

Installation Effects of a Propeller Mounted on a Wing with Coanda Flap. Part II: Numerical Investigation and Experimental Validation

Installation Effects of a Propeller Mounted on a Wing with Coanda Flap. Part II: Numerical Investigation and Experimental Validation

Installation: numerical investigation

Advanced open rotor noise prediction

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