Propeller Signatures and Their Use

Johnston, J. F.; Donham, R. E.; Guinn, W. A.

doi:10.2514/3.57583

Cited by 29 publications

(20 citation statements)

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“…This is comparable to earlier reported results. 1,16 The results for the default angle set are also reasonably close to those of the optimum angle sets in most cases (except at FL280), indicating that the default angle set is a relatively good compromise, although other optimisations strategies may produce better results for the aircrew at high-workload stations. Interestingly, the results for the default and best cases are practically the same for 220 KIAS at 3000 ft, and this is also reflected in the angle sets, which are no more than 2° apart.…”

Section: E Synchrophase Angle Optimisationsupporting

confidence: 48%

“…1 Embodiments of the theory have since appeared in a number of other papers and patents. 16,18,19 In this theory, the total propeller-related noise or vibration at a particular cabin location is calculated by taking the vector sum of the contributions from each propeller.…”

Section: Propeller Signature Theorymentioning

confidence: 99%

“…It is believed that this global reduction arises from the rearrangement of the relative amplitudes of the fuselage vibration modes in such a way that they couple less efficiently with the interior cabin acoustic, or floor vibration, modes. However, 1 Senior Engineer, DSTO -Air Vehicles Division, 506 Lorimer Street, Fishermans Bend VIC 3207, david.blunt@dsto.defence.gov.au; also Ph.D. candidate at the School of Mechanical Engineering, The University of Adelaide, SA 5005, Australia; non-member. 2 Principal Engineer, DSTO -Air Vehicles Division, 506 Lorimer Street, Fishermans Bend VIC 3207, non-member.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5] Typical blade-pass frequencies range from 60 Hz to 120 Hz, and the passive control of these frequencies can be difficult, due to the weight penalties involved. 6 However, most aircraft with two or more propellers have synchrophasers, and previous analytical and experimental studies have indicated that synchrophasing can globally reduce interior noise and vibration, 1,[7][8][9][10][11][12][13][14][15][16] not just redistribute it. It is believed that this global reduction arises from the rearrangement of the relative amplitudes of the fuselage vibration modes in such a way that they couple less efficiently with the interior cabin acoustic, or floor vibration, modes.…”

Section: Introductionmentioning

confidence: 99%

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Propeller Synchrophase Angle Optimisation Study

Blunt

Rebbechi

2007

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

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[Abstract] Interior noise and vibration can be a serious problem in military propeller aircraft. Noise levels often exceed 100 dB, and typical vibration levels can be hazardous to sensitive cargo. This noise and vibration is dominated by the propeller blade-pass frequency and its low-order harmonics. It is generally accepted that propeller synchrophasing is a way of minimising this noise and vibration, however synchrophasing has only achieved limited success in practice. It is thought that the reasons for this are twofold: firstly, the synchrophase angles may be poorly optimised, and secondly, the optimal synchrophase angles may be influenced by flight conditions such as airspeed and altitude. This paper outlines an investigation into these effects for the Royal Australian Air Force AP-3C Orion and C-130J-30 Hercules aircraft. Comprehensive flight trials to examine and quantify these effects were conducted in November 2006. The C-130J-30 trial also included different cargo configurations. Twenty one microphones and seven accelerometers were used in the AP-3C trial, and thirty three microphones, eighteen floor accelerometers and fifteen cargo accelerometers were used in the C-130J-30 trial. Preliminary results are presented for the AP-3C trial. These show that the optimum synchrophase angles do change with altitude and airspeed, and compromises must be made to accommodate these effects.

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Section: E Synchrophase Angle Optimisationsupporting

confidence: 48%

Section: Propeller Signature Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Propeller Synchrophase Angle Optimisation Study

Blunt

Rebbechi

2007

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

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“…Based on the data from flight experiments, the identification and use of the noise and vibration signatures of individual propellers are analyzed. These signatures are used for synchrophase optimization [16], In order to meet the real-time requirement of synchrophasing control system, this paper demonstrates an improved noise vector modeling and synchrophase optimization method via laboratory experiments.…”

Section: Introductionmentioning

confidence: 99%

Propeller Synchrophase Angle Optimization of Turboprop-Driven Aircraft—An Experimental Investigation

Huang

Sheng

Wang

2014

Journal of Engineering for Gas Turbines and Power

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Propeller synchrophasing is an effective way of reducing interior noise and vibration of turboprop-driven aircraft. However, synchrophasing has achieved limited success in practice for the reason that the predetermined phase angles are not acoustically opti mized for maximum noise reduction during all flight conditions. An investigation has been conducted out which includes two folds: first, the noise vector based on laboratory experimental data has been modeled and second, optimal phase to acquire minimum noise is obtained via optimization search. An improved identification method of vector noise model which can be less dependent to noise phase message is presented. Compared with traditional methods, this method can greatly reduce the real-time requirement between phase optimization model and control model or sound acquiring model, so it can eliminate the influence which communication delay brings on identification precision. A synchrophasing experimental platform is established to verify the vector noise modeling. It adopts two propellers-driven servo motors to simulate the interior noise environment o f the aircraft. The influence of the date sampling condition on identification is also reseat ched. Ant colony optimization with two improvements is applied to phase optimiza tion o f four propellers. Simulation results show that the improved algorithm requires much less calculation.

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Comparison of Two Propeller Source Models for Aircraft Interior Noise Studies

Mahan

Fuller

1986

Aero- And Hydro-Acoustics

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Propeller Signatures and Their Use

Cited by 29 publications

References 0 publications

Propeller Synchrophase Angle Optimisation Study

Propeller Synchrophase Angle Optimisation Study

Propeller Synchrophase Angle Optimization of Turboprop-Driven Aircraft—An Experimental Investigation

Comparison of Two Propeller Source Models for Aircraft Interior Noise Studies

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