Aerodynamic and Basic Acoustic Optimization of a Counter Rotating Open Rotor with Experimental Verification

Schnell, Rainer; Yin, Jianping; Funke, Stefan; Siller, H.

doi:10.2514/6.2012-2127

Cited by 11 publications

(17 citation statements)

References 3 publications

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“…On one hand methods are developed to understand the noise generation mechanisms, 3, 4 on the other hand an automate design-to-noise procedure is being set up. [5][6][7] In the frame of the European Research Program "Joint Technology Initiative Clean-Sky", a task is dedicated to "Innovative CROR blade and pylon design". The implementation of serrations on the front rotors trailing edge is numerically investigated as a possible technology to reduce the tonal noise.…”

Section: Introductionmentioning

confidence: 99%

On the influence of trailing-edge serrations on open-rotor tonal noise

Weckmüller

Guérin

2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

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Tonal noise of contra-rotating open rotors can be divided into self and interaction noise. The latter can be subdivided into potential field interaction noise, noise due to the interaction of the front-rotor wakes with the aft-rotor blades and tip vortex interaction noise. The excited tonal sound field is closely related to the properties of the impinging wakes provided that the tip vortex interaction is not the dominant source of interaction noise. Designing the trailing edge of the front-rotor blades with serrations will enhance the mixing in the wakes which should have a beneficial effect on the interaction tones. This process is investigated with 3D RANS calculations of 3 serration designs. Through assessment of the wake properties one configuration is down selected for evaluation of the far-field sound levels. These are computed using a 3D URANS approach coupled to an integral method that implements the FW-H acoustic analogy. The effect observed with the serrations on the far-field directivity is twofold: at low frequencies the sound energy is redistributed in the polar arc; at higher frequencies a systematic reduction of the sound emission is observed.

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Section: Introductionmentioning

confidence: 99%

On the influence of trailing-edge serrations on open-rotor tonal noise

Weckmüller

Guérin

2012

18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

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“…Apart from the shown comparisons with experimental data a number of studies deal with the comparisons of open-rotor simulation with different solver and methods (Delattre and Schnell (17) and Lepot et al (18) ). A comparison with acoustic data taken at WT104 wind tunnel as described by Funke et al (19) can be found in Schnell et al (20) . (dashed lines/squares) (10) .…”

Section: Aerodynamicsmentioning

confidence: 97%

“…In order to decrease the computation time and increase the accuracy, the phase-shift method was applied. The application of URANS to CROR is discussed by Schnell et al (10,20) and Weckmüller and Guérin (27,28) . The mesh strategy developed for CROR is presented in Fig.…”

Section: Numerical Approachmentioning

confidence: 99%

Performance prediction and progress towards multi-disciplinary design of contra-rotating open rotors

Guérin¹,

Schnell²,

Becker³

2014

Aeronaut. j. (1968)

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At DLR's Institute of Propulsion Technology, the prediction tools and multi-disciplinary optimisation strategies developed for turbofan engines have been extended to contra-rotating open rotors (CROR). Thereby the objective has been to appraise and improve the performance of CROR engines and thus to reduce their environmental impact. The present paper reviews the intermediate progress achieved in this scope. The prediction is based on analytical and CFD methods and covers the fields of engine performance analysis, aerodynamics and acoustics. The aerodynamic and acoustic results could be partly validated through the comparison to experimental data obtained from wind-tunnel tests. In a multi-disciplinary approach the aforementioned aspects are optimised together. First results of an aero-acoustic optimisation are presented. Furthermore this paper undertakes some comparison between high-bypass ratio turbofan engines and open-rotor concepts.

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“…The efficiency of the CROR system mainly comes from the reduction of the front propeller slipstream swirl by the impingement of the aft propeller slipstream, which will also lead to the extra axial acceleration of the flow downstream when it passes through the aft propeller; therefore, CROR systems can generate greater thrust [6][7][8][9]. However, the aerodynamic interactions caused by the front propeller blade tip vortices impinging on the blade tip vortices generated by the aft propeller will result in the noise emissions as well as vibrations [10,11], making it a main problem for the development of the CROR system in the application of modern aircraft [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

CFD Analysis of Contrarotating Open Rotor Aerodynamic Interactions

Shi

Yang

et al. 2018

International Journal of Aerospace Engineering

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High efficiency and low fuel consumption make the contrarotating open rotor (CROR) system a viable economic and environmentally friendly powerplant for future aircraft. While the potential benefits are well accepted, concerns still exist with respect to the vibrations and noise caused by the aerodynamic interactions of CROR systems. In this paper, emphasis is placed on the detailed analysis of the aerodynamic interactions between the front and aft propellers of a puller CROR configuration. For the first step, unsteady Reynolds-averaged Navier-Stokes (URANS) simulations coupled with dynamic patched grid technology are implemented on the isolated single-rotating propeller (SRP) configuration in various operating conditions in order to test the accuracy and feasibility of the numerical approach. The numerical results are verified by a wind tunnel test, showing good agreements with the experimental data. Subsequently, the URANS approach is applied to the CROR configuration. The numerical results obtained through the URANS approach help to improve the understanding of the complex flow field generated by the CROR configuration, and the comparison of SRP flow field and CROR flow field allows for a detailed analysis of the aerodynamic interactions of the front propeller blade wakes and tip vortices with the aft propeller. The main reason of the aerodynamic interactions is the mutual effects of the blade tip vortices, and the aft propeller reduces the strength of the blade tip vortices of the front propeller. Aerodynamic interactions will lead to the periodic oscillations of the aerodynamic forces, and the frequency of the oscillations is linked to the blade numbers. In addition, a CROR has a larger thrust and power coefficient than that of the SRP configuration in the same operating conditions. The URANS approach coupled with a dynamic patched grid method is tested to be an efficient and accurate tool in the analysis of propeller aerodynamic interactions.

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Aerodynamic and Basic Acoustic Optimization of a Counter Rotating Open Rotor with Experimental Verification

Cited by 11 publications

References 3 publications

On the influence of trailing-edge serrations on open-rotor tonal noise

On the influence of trailing-edge serrations on open-rotor tonal noise

Performance prediction and progress towards multi-disciplinary design of contra-rotating open rotors

CFD Analysis of Contrarotating Open Rotor Aerodynamic Interactions

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