Application of a RANS-Informed Analytical Model for Fast Noise Prediction of Contra Rotating Open Rotors

2017 ◽  
Author(s):  
Damiano Tormen ◽  
Pietro Giannattasio ◽  
Alessandro Zanon ◽  
Helmut Kühnelt ◽  
Michele De Gennaro
Keyword(s):  
Analytical Model ◽  
Vortex Flow ◽  
Domain Model ◽  
Tip Vortex ◽  
Acoustic Measurements ◽  
Open Rotor ◽  
Noise Measurements ◽  
Blade Tip ◽  
Fast Prediction ◽  
Analytical Frequency

The present work focuses on the fast prediction of the interaction noise (IN) components of a Contra Rotating Open Rotor (CROR) engine at take-off. The flow field past the CROR is computed using a steady RANS approach coupled with the concept of mixing plane between the rotors to remove the flow unsteadiness due to the propeller interaction. The effects of such interaction are then recovered applying the analytical model of Jaron et al. (2014), balanced with data extracted from the RANS solution, to extrapolate the information about the wake of the front rotor and the potential flow fields through the mixing plane. This RANS-informed approximation allows recovering the unsteadiness of the flow-blades interaction in terms of unsteady blade response. The tonal noise at the blade passing frequency and the interaction noise are then estimated using the analytical frequency domain model proposed by Hanson (1985). The present method for the fast prediction of CROR noise has been validated by comparison with the results of URANS simulations and noise measurements. CROR geometry UDF F7/A7 with both 8 × 8 and 11 × 9 blade counts has been considered. The flow velocity profiles extrapolated through the mixing plane agree well with the URANS results, except in the vicinity of the blade tip, where the analytical extrapolation method is not able to deal properly with the strongly 3D tip vortex flow. The comparison of the predicted interaction noise with acoustic measurements shows that the present fast RANS-informed approach is capable of estimating the directivity of the CROR noise with reasonable accuracy.

A Contra-Rotating Open Rotor Noise Reduction Methodology by Using Anhedral Blade Tip

2021 ◽  
pp. 1-26
Author(s):  
Tianxiao Yang ◽  
Wenjun Yu ◽  
Dong Liang ◽  
Xiang He ◽  
Zhenguo Zhao
Keyword(s):  
Noise Reduction ◽  
Polar Angle ◽  
Aerodynamic Performance ◽  
Tip Vortex ◽  
Rotor Noise ◽  
Lean Angle ◽  
Open Rotor ◽  
Blade Tip

Abstract In this paper, a novel Contra-Rotating Open Rotor (CROR) noise reduction methodology based upon the anhedral blade tip applied to the front blade is developed. Results indicate that anhedral blade tip can provide noise reduction over 60 deg. polar angle range in both upstream and downstream areas at takeoff condition. The noise reduction becomes more significant as the lean angle of anhedral blade tip increases, and the maximum noise reduction is over 4 dB. Further analysis shows that anhedral blade tip decreases the strength and size of blade tip vortex shed from the front blade, and reduces its interaction with the rear rotor, which decreases the fluctuation of loading acting on the rear rotor and its loading noise. Furthermore, the anhedral blade tip does not have strong effect on the aerodynamic performance of CROR at cruise.

602 Discrete Frequency Noise Generated from Blade Tip Vortex Flow of a Propeller Fan

2013 ◽  
Vol 2013.66 (0) ◽  
pp. 165-166
Author(s):  
Ikki Torise ◽  
Soichi SASAKI ◽  
Hidechito HAYASHI ◽  
Hiroaki MURAKAMI
Keyword(s):  
Vortex Flow ◽  
Tip Vortex ◽  
Frequency Noise ◽  
Discrete Frequency ◽  
Blade Tip

Semi-Analytical Tip Vortex Model for Fast Prediction of Contrarotating Open Rotor Noise

AIAA Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Damiano Tormen ◽  
Pietro Giannattasio ◽  
Alessandro Zanon ◽  
Michele De Gennaro ◽  
Helmut Kühnelt
Keyword(s):  
Tip Vortex ◽  
Vortex Model ◽  
Rotor Noise ◽  
Open Rotor ◽  
Fast Prediction

scholarly journals Rotor Interaction Noise in Counter-Rotating Propfan Propulsion Systems

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Andreas Peters ◽  
Zoltán S. Spakovszky
Keyword(s):  
Polar Angle ◽  
Secondary Flows ◽  
Tip Vortex ◽  
System Level ◽  
Analysis Tool ◽  
Acoustic Analogy ◽  
Wake Interaction ◽  
Open Rotor ◽  
And Performance ◽  
The Individual

Due to their inherent noise challenge and potential for significant reductions in fuel burn, counter-rotating propfans (CRPs) are currently being investigated as potential alternatives to high-bypass turbofan engines. This paper introduces an integrated noise and performance assessment methodology for advanced propfan powered aircraft configurations. The approach is based on first principles and combines a coupled aircraft and propulsion system mission and performance analysis tool with 3D unsteady, full-wheel CRP computational fluid dynamics computations and aeroacoustic simulations. Special emphasis is put on computing CRP noise due to interaction tones. The method is capable of dealing with parametric studies and exploring noise reduction technologies. An aircraft performance, weight and balance, and mission analysis was first conducted on a candidate CRP powered aircraft configuration. Guided by data available in the literature, a detailed aerodynamic design of a pusher CRP was carried out. Full-wheel unsteady 3D Reynolds-averaged Navier-Stokes (RANS) simulations were then used to determine the time varying blade surface pressures and unsteady flow features necessary to define the acoustic source terms. A frequency domain approach based on Goldstein’s formulation of the acoustic analogy for moving media and Hanson’s single rotor noise method was extended to counter-rotating configurations. The far field noise predictions were compared to measured data of a similar CRP configuration and demonstrated good agreement between the computed and measured interaction tones. The underlying noise mechanisms have previously been described in literature but, to the authors’ knowledge, this is the first time that the individual contributions of front-rotor wake interaction, aft-rotor upstream influence, hub-endwall secondary flows, and front-rotor tip-vortices to interaction tone noise are dissected and quantified. Based on this investigation, the CRP was redesigned for reduced noise incorporating a clipped rear-rotor and increased rotor-rotor spacing to reduce upstream influence, tip-vortex, and wake interaction effects. Maintaining the thrust and propulsive efficiency at takeoff conditions, the noise was calculated for both designs. At the interaction tone frequencies, the redesigned CRP demonstrated an average reduction of 7.25 dB in mean sound pressure level computed over the forward and aft polar angle arcs. On the engine/aircraft system level, the redesigned CRP demonstrated a reduction of 9.2 dB in effective perceived noise (EPNdB) and 8.6 EPNdB at the Federal Aviation Regulations (FAR) 36 flyover and sideline observer locations, respectively. The results suggest that advanced open rotor designs can possibly meet Stage 4 noise requirements.

Acoustic Measurements of a Contra-Rotating Open Rotor in an Open Jet Wind-Tunnel

2012 ◽  
Vol 11 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Stefan Funke ◽  
Larisa Kim ◽  
Henri Siller
Keyword(s):  
Wind Tunnel ◽  
Acoustic Measurements ◽  
Open Rotor

Investigation of Helicopter Rotor-Blade-Tip-Vortex Alleviation Using a Slotted Tip

AIAA Journal ◽  
2004 ◽  
Vol 42 (3) ◽  
pp. 524-535 ◽  
Author(s):  
Yong Oun Han ◽  
J. Gordon Leishman
Keyword(s):  
Rotor Blade ◽  
Tip Vortex ◽  
Helicopter Rotor ◽  
Helicopter Rotor Blade ◽  
Blade Tip

URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

2017 ◽  
Author(s):  
Gi-Don Na ◽  
Frank Kameier ◽  
Nils Springer ◽  
Michael Mauß ◽  
C. O. Paschereit
Keyword(s):  
Applied Sciences ◽  
Numerical Simulations ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Acoustic Measurements ◽  
Noise Emission ◽  
Industrial Partner ◽  
University Of Applied Sciences ◽  
Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

Investigation of the Blade Tip Clearance Effects on Performance and Stability of a Mixed-Flow Pump: High Speed Camera Recordings of the Flow Structures, Local Measurements and Numerical Simulation

2015 ◽  
Author(s):  
Alberto Serena ◽  
Lars E. Bakken
Keyword(s):  
High Speed ◽  
Detailed Comparison ◽  
Performance Comparison ◽  
Tip Clearance ◽  
Tip Vortex ◽  
High Speed Camera ◽  
Tip Leakage Flow ◽  
Quality Video ◽  
Local Measurements ◽  
Blade Tip

The tip leakage flow affects turbomachines performance generating losses and reducing the effective blading; in addition, unsteady phenomena arise, negatively influencing the machine stability. In this paper, an overview of the existing models is presented. Local measurements of the pressure pulsations, visual flow observations and high quality video recordings from a high speed camera are performed in a novel pump laboratory, which provides the desired visualization of the rotating channels, and allows to study the fluctuating and intermittent nature of this phenomenon, and detect any asymmetry among the channels. A detailed comparison of the vortex tip structure for various tip clearances and with a whole set of numerical simulations finally completes the analysis. The three main focus areas are: tip vortex location, structure and evolution, performance comparison between shrouded and open impeller, at different tip clearance sizes, and study of the rotating instabilities.

scholarly journals Numerical Investigation of Tip-Vortex Cavitation Noise of an Elliptic Wing Using Coupled Eulerian-Lagrangian Approaches

2020 ◽  
Vol 10 (17) ◽  
pp. 5897 ◽  
Author(s):  
Garam Ku ◽  
Cheolung Cheong ◽  
Hanshin Seol
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Vortex Flow ◽  
Acoustic Pressure ◽  
Tip Vortex ◽  
Experimental Result ◽  
Cavitation Noise ◽  
Navier Stokes Equation ◽  
Tip Vortex Cavitation ◽  
Cavitation Inception

In this study, a numerical methodology is developed to investigate the tip-vortex cavitation of NACA16-020 wings and their flow noise. The numerical method consists of a sequential one-way coupled application of Eulerian and Lagrangian approaches. First, the Eulerian method based on Reynolds-averaged Navier–Stokes equation is applied to predict the single-phase flow field around the wing, with particular emphasis on capturing high-resolution tip-vortex flow structures. Subsequently, the tip-vortex flow field is regenerated by applying the Scully vortex model. Secondly, the Lagrangian approach is applied to predict the tip-vortex cavitation inception and noise of the wing. The initial nuclei are distributed upstream of the wing. The subsequent time-varying size and position of each nucleus are traced by solving spherically symmetric bubble dynamics equations for the nuclei in combination with the flow field predicted from the Eulerian approach. The acoustic pressure at the observer position is computed by modelling each bubble as a point source. The numerical results of the acoustic pressure spectrum are best matched to the measured results when the nuclei number density of freshwater is used. Finally, the current numerical method is applied to the flows of various cavitation numbers. The results reveal that the cavitation inception determined by the predicted acoustic pressure spectrum well matched the experimental result.

Numerical Experiments for Flow Around a Ducted Tip Hydrofoil

2002 ◽  
Author(s):  
Hildur Ingvarsdo´ttir ◽  
Carl Ollivier-Gooch ◽  
Sheldon I. Green
Keyword(s):  
Turbulence Model ◽  
Vortex Core ◽  
Vortex Flow ◽  
Computational Study ◽  
Near Field ◽  
Vortex Formation ◽  
Tip Vortex ◽  
Navier Stokes ◽  
Computational Studies ◽  
Tip Vortices

The performance and cavitation characteristics of marine propellers and hydrofoils are strongly affected by tip vortex behavior. A number of previous computational studies have been done on tip vortices, both in aerodynamic and marine applications. The focus, however, has primarily been on validating methods for prediction and advancing the understanding of tip-vortex formation in general, rather than showing effects of tip modifications on tip vortices. Studies of the most relevance to the current work include computational studies by Dacles-Mariani et al. (1995) and Hsiao and Pauley (1998, 1999). Daeles-Mariani et al. carried out interactively a computational and experimental study of the wingtip vortex in the near field using a full Navier-Stokes simulation, accompanied with the Baldwin-Barth turbulence model. Although they showed improvement over numerical results obtained by previous researchers, the tip vortex strength was underpredicted. Hsiao and Pauley (1998) studied the steady-state tip vortex flow over a finite-span hydrofoil, also using the Baldwin-Barth turbulence model. They were able to achieve good agreement in pressure distribution and oil flow pattern with experimental data and accurately predict vertical and axial velocities of the tip vortex core within the near-field region. Far downstream, however, the computed flow field was overly diffused within the tip vortex core. Hsiao and Pauley (1999) also carried out a computational study of the tip vortex flow generated by a marine propeller. The general characteristics of the flow were well predicted but the vortex core was again overly diffused.

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