Use of fan rig data for the understanding and prediction of fan broadband noise and noise changes due to a variable area nozzle

This thesis presents the results of the research component of this EngD, entitled<br/>Use of fan rig data for the understanding and prediction of fan broadband noise and noise<br/>changes due to a variable area nozzle<br/>As suggested by the title, fan rig noise measurements form an integral part of this thesis. The<br/>analysis of a database of rig noise measurements forms the first section of this thesis, in two<br/>parts. The first part describes the analysis of a set of fan rig noise measurements, including the<br/>variation of fan broadband and tone noise in forward and rearward arcs. The second part<br/>examines a large database of fan rig noise measurements, and attempts to derive correlations<br/>of fan broadband noise and fan performance parameters. Cluster Analysis, Principle<br/>Component Analysis, and Regression Analysis are used to understand and describe the<br/>underlying physics of broadband noise generation and the relationships between these<br/>predictors.<br/><br/>The second section of this thesis uses a cascade broadband noise model to investigate rotorstator<br/>broadband noise. Predictions of the broadband noise from this noise model are<br/>compared to rig measurements, showing good accuracy. The underlying physics of rotorstator<br/>broadband noise generation is investigated by performing two parametric studies using<br/>the broadband noise model. The first parametric study investigates the effect on broadband<br/>noise of simple flow and geometric parameters, namely number of vanes, vane chord, vane<br/>stagger angle, and rotor wake turbulence intensity, turbulent length scale, and flow Mach<br/>number onto the cascade. These results are used to derive scaling power laws for the<br/>prediction of changes in broadband noise due to changes in these parameters. The second<br/>parametric study expands upon this by investigating the effect on broadband noise of the fan<br/>design parameters shaft speed, pressure ratio, and efficiency, at approach, cutback and cruise<br/>conditions. The variation in broadband noise due to these design parameters is explained by<br/>considering the underlying flow and geometric parameters such as number of vanes and Mach<br/>number, and the scaling power laws based on these simple parameters are used to predict the<br/>change in broadband noise between different performance points.<br/>The final section of this thesis investigates the effect of varying exhaust nozzle area on total<br/>engine noise. A new method is presented that allows the transfer of changes in fan rig noise to<br/>Eugene P. Deane EngD Thesis September 2009 2<br/>engine noise predictions, to estimate the change in fan noise due to the pressure ratio changes<br/>brought about by a variable area nozzle. Changes in engine noise are investigated for<br/>approach, cutback, and sideline conditions, and the application of the new method assessed.<br/><br/>As the research displayed in this thesis is closely linked to industry, the foundation of work<br/>presented in several chapters is dependent on data or figures that are commercially sensitive.<br/>It has therefore been necessary to create a confidential appendix (Appendix X) to include<br/>these commercially sensitive items. These additional results and figures in Appendix X are<br/>supplementary in nature, and sufficient results are presented in the public thesis to illustrate<br/>the results of the various chapters. Where supplementary information and results are available,<br/>this is clearly indicated at the pertinent point in the published thesis, along with the section of<br/>Appendix X where the information can be found.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2009

Author dc:creator

• Deane, Eugene Pio

Advisor dc:contributor.advisor

• Joseph, P.F.