Innovative methods in organ pipe design

Peter Rucz

rucz@hit.bme.hu

Supervisor: Fulop Augusztinovicz

PhD Workshop13/12/2010

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Outline

I IntroductionI Motivation

I Project backgroundI The INNOSOUND projectI INNOScale scaling software

I Research activityI Summary of the past semestersI Novel pipe modelingI Fluid dynamic simulations

I PhD processI Educational activityI Language examsI Publications

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Motivation

I Scaling and tuning processes of organpipes are still performed according tothe rules laid down in the 19th century

I Possibilities of numerical techniquesI Speed up the scaling and tuningI Obtain information on key properties

of the pipe sound

I Research objectivesI Acoustic simulation of various pipesI Validation and comparison with

measurementsI Develop a coupled acoustical / fluid

dynamical modelI Simulation of the sound generation

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Project background

INNOSOUND - Innovative Methods and Tools for the SoundDesign of Organ Pipes (EU project)

I September 2008 - December 2010I Main objectives

I Improvement of the sound quality of labial organ pipes bydeveloping tuning and voicing methods

I Reduction of the cost of the scaling process by scientific pipedesign tools

I Reduction of the effort spent on pipe manufacturing:development of a scaling software based on scientific results

I PartnersI Scientific: Fraunhofer Institute for Building Physics, Stuttgart,

BME HIT – Laboratory of AcousticsI Industrial: 10 European organ builder firms

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

INNOScale – The innovative scaling software

The final product of the project is the scaling software

I Developed under Matlab + Java

I User friendly graphical interfaceI Innovative design tools

I Customizable and highly flexible pipe mensuration systemI Novel methods for the calculation of various parameters

I Calculation based on simulation and experiment results

I Publication possibilityI Journal of the International Society of Organ builders

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Summary of the last two years’ research

I Three different techniques were examinedI Indirect boundary elements (IBEM)I Coupled finite / boundary element

method (FEM/BEM)I Finite element method with infinite

elements (FEM/IEM)

I The most important steps in the processI Development of simulation techniquesI Simulation of acoustic impedances and

length correctionsI Comparison to analyitical and

measurement results (good agreement)I Prediction of sounding characteristics

I What is the advantage of simulationcompared to analytical solution?

IBEM FEM/BEM FEM/IEM

BEM FEM/IEM

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Tuning slot (expression) simulation I.

The most common tuning devicesof open labial organ pipes

I Their dimensioning isperformed based on tradition

I The impedance model failsto treat the tuning slotcorrectly

I How does the simulationmodel perform?

Mouth

Open end(AO )

Tuning slot (AE )

ZPZM

ZRE

ZRO ZT ZE

ZR ∝1

A; AO � AE → ZRO � ZRE

ZE ≈ 0; ZT � ZRE

Z = ZM + ZP + (ZRE + ZE )× (ZRO + ZT )

The radiation impedance of the openend is dominant over the tuningslot’s impedance in this model.

This contradicts to our observations

and measurement results.

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Tuning slot (expression) simulation II.

I Simulations performed with different tuning slot sizesI Comparison of resonant frequencies to measurement resultsI Resultant relative errors of fundamental frequencies

Analytical: 5-10%; Simulation 0.5-1%I Conclusion

I 1D analytical models cannot treat tuning slotsI 3D simulation is needed for correct predictions

Resonant frequencies in HzMode Meas. Ana. Sim.1st 194.0 180.8 194.02nd 403.9 366.0 393.03rd 603.2 556.0 595.54th 803.0 748.0 797.05th 998.2 939.0 989.56th 1170.0 1110.0 1165.57th 1345.0 1255.0 1342.58th 1535.0 1422.0 1537.59th 1735.0 1612.0 1743.0

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

The CBS algorithm I. - Brief summary

CBS = Characteristic Based Split algorithm

I Introduced by Zienkiewicz et al. around 1995I General, capable of solving a great variety of flow problems

I Solves the (in)compressible Navier–Stokes set of equations

I It uses the characteristic–Galerkin methodI The coordinate system follows the flow characteristicsI Spatial discretization by the standard Galerkin method (FE)

I Uses splitting of the flow velocity variable

My implementation

I Developed under Matlab, August 2010I Capable of solving simple flow problems

I Viscouos, incompressible, laminar, steady state flows

I Validated on a few example experiments

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

The CBS algorithm II. - Example 1.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.1

0.2

0.3

0.4

0.5

Normalized x velocity

Nor

mal

ized

y d

ista

nce

Velocity profiles of viscous laminar flow in a long tube (Re = 200)

x = 0.5x = 1x = 1.5x = 2x = 2.5x = 3x = 3.5x = 4

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

The CBS algorithm III. - Example 2.

x = 4 x = 5 x = 6 x = 7 x = 8 x = 9 x = 10 x = 11 x = 12 x = 13

Velocity profile behind a backward facing step. (Re = 200)

Normalized x velocity profiles at different distances. (Range: [−0.5 1.5])

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Large eddy simulation

Large Eddy Simulation (LES) is a quickly developing field ofturbulence simulation

I Basic conceptsI Capture the largest eddies in the flow, model the othersI The former have the most kinetic energy that governs the flowI Save computational effort, keep the accuracyI Solve a time and space filtered set of the NSSEI Use a sub-grid model to represent smaller scalesI Inverse filtering to obtain information on the filtered scalesI Lot of open questions: e.g. wall boundary conditions

I ImplementationI Commercial: Fluent, etc.I Open source: OpenFOAM

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Future research

I Development of a coupled acoustic / fluid dynamic modelI Couple the acoustic / fluid dynamic computation in a hybrid

approachI Join the two meshes with proper boundary conditionsI Active coupling between the two systemsI Reduce the computational effort compared to DNSI Compute the radiated sound of a turbulent flow

I Near and far field calculation

I Possible applicationsI Sound generation simulation of wind driven musical

instrumentsI Calculation of losses due to development of whirlsI Calculation of the interaction between the acoustic and fluid

dynamic systems

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

PhD Process I.

I Start date: September 2009I Subjects

I 3 obligatory and 3 facultative subjects accomplishedI Fluid dynamic subjects in this semester

I Department of Fluid MechanicsI Fundamentals of fluid mechanics (Tamas Lajos)I Large eddy simulation (Mate Lohasz)

I Educational activities:I 1st semester

I Acoustic measurements laboratoryI Measurement laboratory

I 2nd semesterI Laboratory II.I Sound engineering basics laboratory

I This semester: Measurement laboratory (≈ 6 hrs. a week)

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

PhD Process II.

I Language examsI English advanced, C type; Latin intermediate, C typeI Currently preparing for the Spanish intermediate examI Language exam in May 2011

I Travelings on scientific purposeI August 2009: training at FFT company, BelgiumI January 2010: Six weeks at Fraunhofer IBP, StuttgartI September 2010: ISAAC21 course, BelgiumI October 2010: Two weeks in Stuttgart

I OtherI Applied for the Huszty Denes Prize, 2011.

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Publications

I Conference papersI ICSV16 (2009, Krakow): Conference paper in EnglishI ISMA2010 (Leuven): Conference paper in English

I Journal papersI Acoustic review, 2009.

(Journal paper in English, published in Hungary. In press.)I Paper submitted to Applied Acoustics, 2010.

(In revision status currently.)

I Publication plansI Numerical acoustic toolboxI INNOScale software (JISO)

P. Rucz Innovative methods in organ pipe design

Introduction Project background Pipe simulations Fluid dynamic simulation PhD Process

Thank you for your attention!

P. Rucz Innovative methods in organ pipe design