Periodic Reporting for period 2 - INVENTOR (INnoVative dEsign of iNstalled airframe componenTs for aircraft nOise Reduction)
Periodo di rendicontazione: 2021-11-01 al 2023-04-30
Aircraft noise has two major contributors, the engines and the airframe, and airframe noise is mainly generated by the landing gears (LGs) and the high lift devices (HLDs).
The main goals of INVENTOR are to understand the physics of the airframe noise of business jet (BJ) and short-medium range (SMR) transport aircraft, and decrease this noise thanks to an intensive use of advanced flow/noise numerical prediction methods, validated with several experimental databases, relying on two approaches:
• Innovative “Design-To-Noise” (DTN) process will be used for numerically improving LG components and achieving low noise designs for slat tracks, spoilers and Krueger slats in HLDs.
• Passive and active Noise Reduction Technologies (NRTs) will be developed or improved, flow-through fairings and air curtains for LGs and porous surfaces and fluidic actuators for HLDs.
The project will contribute to reach the Flightpath 2050 goals pursued by ACARE SRIA on aviation noise, i.e. to reduce perceived noise emission of flying aircraft by 65%. The main KPI of noise reduction will be far-field noise reductions from installed LGs and HLDs at landing/approach by, respectively, 2-3 and 1 dB(A).
INVENTOR consortium gathers all required numerical/experimental expertise from RTOs, Universities, Industries and SMEs.
The main goals of INVENTOR are to understand the physics of the airframe noise of business jet (BJ) and short-medium range (SMR) transport aircraft, and decrease this noise thanks to an intensive use of advanced flow/noise numerical prediction methods, validated with several experimental databases, relying on two approaches:
• Innovative “Design-To-Noise” (DTN) process will be used for numerically improving LG components and achieving low noise designs for slat tracks, spoilers and Krueger slats in HLDs.
• Passive and active Noise Reduction Technologies (NRTs) will be developed or improved, flow-through fairings and air curtains for LGs and porous surfaces and fluidic actuators for HLDs.
The project will contribute to reach the Flightpath 2050 goals pursued by ACARE SRIA on aviation noise, i.e. to reduce perceived noise emission of flying aircraft by 65%. The main KPI of noise reduction will be far-field noise reductions from installed LGs and HLDs at landing/approach by, respectively, 2-3 and 1 dB(A).
INVENTOR consortium gathers all required numerical/experimental expertise from RTOs, Universities, Industries and SMEs.
During the 3 first years of the project, all experimental and numerical studies of passive/active NRTs at component level have been specified and almost completed, in preparation of the final assessment at aircraft level, to be achieved in the last period.
For LGs:
Passive porous flow-through fairings (wire meshes, perforated plates, Diamond-Lattice cells and metallic wool) have been physically characterized in B2A@ONERA and WAABLIEF@VKI (May-Sept 21) to calibrate numerical models, and then tested in A-Tunnel@TUD (Sept 21) on a LAGOON model, for the validation of on-going computations achieved without/with fairings. They have been also tested on a realistic generic BJ main LG (GB-MLG) model in AWB@DLR (Oct 21 - Jan 22), also with associated numerical simulations. Finally, the best fairings were tested on the same LG at full scale in the S2A in Feb 23 (a 2nd entry is planned in Oct 23).
Local and global active air curtain have been first designed via CFD computations on two LGs to evaluate the air mass rates and tune-up the designs. Several local blowing devices were tested in AWB@DLR on a LAGOON LG in Jan 22, showing significant self-noise generated by the nozzles. Improved designs of more silent nozzles were tested in AWB (March 23) on a GB-MLG, outcomes are under investigations.
The DTN activity aims at reducing the noise of a reference conventional 2-wheel MLG adapted to a SMR aircraft by modifying a selection of geometrical parameters. The acoustic influence of each parameter is computed at scale 1/4 using the ProLB Lattice Boltzmann solver for the local unsteady flow and an integral method for the radiated noise. Computations are validated through experiments in AWB on the reference LG (July 22) at scale 1/7.5 (isolated) and 1/12.5 (partly installed). An initial numerical benchmark on the reference design has been achieved by the partners to setup best practices. In the current step, partners share a computational matrix to evaluate several design modifications and converge to an optimised design, to be also tested in AWB by end of 2023. In a side activity, a 4-wheel MLG with similar MTOW is evaluated by one partner. In WP5, both reference and optimized 2-wheel LG will be assessed at scale 1/12.5 on the 3DFNGY model.
ARTEM has highlighted the mechanism of landing gear wake/flap interaction noise, and INVENTOR addresses its reduction by using porous materials on the flap. The ARTEM test set-up has been re-used in AWB@DLR to survey the LG wake. RANS computations of the mean flow have been achieved, then the LG/flap interaction will be simulated with an Euler solver using Immersed Boundary Conditions and synthetic turbulence. The porous media on the flap will be modeled using the Darcy-Forchheimer model.
For high-lift devices:
Low noise slat tracks and slat porous inserts
14 generic and low noise slat tracks have been acoustically assessed in Sep 21 in AWT@NLR on the flapless 2.5D high-lift wing F16 with a 30° sweep, showing the critical acoustic role of the wing cavity, and the potential of several low noise designs.
In parallel, a preliminary study of porous inserts (Diamond-Lattice cells and polyurethane foam) implemented at the slat suction side of the same model (but 0° sweep) has been achieved in AAWT@UoB in Oct 21. Their space-time features had been characterized in WAABLIEF@VKI to calibrate/validate numerical models implemented in the CFD solvers used in ongoing computations.
In April-May 22, the flow and noise of the same 14 slat tracks and all porous slats (with more inserts with new materials located close to the slat trailing edge) have been assessed in F2@ONERA on the full 3-element F16 model with a 30° sweep, either with the continuous slat configuration or with new inner/outer slat side-edges. Static pressure and PIV maps have been provided to 4 partners undertaking numerical simulations of slat tracks flow/noise. Their noise prediction at the positions of the 120-microphone array in F2 will be compared to experimental data.
Spoiler flow and noise have been extensively assessed in May-June 22 at AWT@UoS on a generic modular wall-mounted spoiler inclined to free stream. All broadband noise source mechanisms have been studied (deflection angle, upstream boundary layer and separation bubble, turbulent wake and side edge vortices). In parallel, numerical simulations with ProLB are under progress on this configuration. In a second step, ProLB will be applied to a more realistic spoiler configuration tested in AWB (OPENAIR).
The Krüger slat noise assessment now relies on the INTONE database, a German project in which one classic slat and two Krüger slat (reference/low noise) configurations were tested on the 3DFNGY model in NWB. CAD and flow conditions of these geometries were provided to 2 partners who achieve flow/noise numerical simulations, with ProLB and STAR-CCM+.
Several specification activities have started in WP5, in which all studied technologies will be assessed on two full generic aircraft models in NWB@DNW, one SMR transport aircraft and one BJ aircraft.
For LGs:
Passive porous flow-through fairings (wire meshes, perforated plates, Diamond-Lattice cells and metallic wool) have been physically characterized in B2A@ONERA and WAABLIEF@VKI (May-Sept 21) to calibrate numerical models, and then tested in A-Tunnel@TUD (Sept 21) on a LAGOON model, for the validation of on-going computations achieved without/with fairings. They have been also tested on a realistic generic BJ main LG (GB-MLG) model in AWB@DLR (Oct 21 - Jan 22), also with associated numerical simulations. Finally, the best fairings were tested on the same LG at full scale in the S2A in Feb 23 (a 2nd entry is planned in Oct 23).
Local and global active air curtain have been first designed via CFD computations on two LGs to evaluate the air mass rates and tune-up the designs. Several local blowing devices were tested in AWB@DLR on a LAGOON LG in Jan 22, showing significant self-noise generated by the nozzles. Improved designs of more silent nozzles were tested in AWB (March 23) on a GB-MLG, outcomes are under investigations.
The DTN activity aims at reducing the noise of a reference conventional 2-wheel MLG adapted to a SMR aircraft by modifying a selection of geometrical parameters. The acoustic influence of each parameter is computed at scale 1/4 using the ProLB Lattice Boltzmann solver for the local unsteady flow and an integral method for the radiated noise. Computations are validated through experiments in AWB on the reference LG (July 22) at scale 1/7.5 (isolated) and 1/12.5 (partly installed). An initial numerical benchmark on the reference design has been achieved by the partners to setup best practices. In the current step, partners share a computational matrix to evaluate several design modifications and converge to an optimised design, to be also tested in AWB by end of 2023. In a side activity, a 4-wheel MLG with similar MTOW is evaluated by one partner. In WP5, both reference and optimized 2-wheel LG will be assessed at scale 1/12.5 on the 3DFNGY model.
ARTEM has highlighted the mechanism of landing gear wake/flap interaction noise, and INVENTOR addresses its reduction by using porous materials on the flap. The ARTEM test set-up has been re-used in AWB@DLR to survey the LG wake. RANS computations of the mean flow have been achieved, then the LG/flap interaction will be simulated with an Euler solver using Immersed Boundary Conditions and synthetic turbulence. The porous media on the flap will be modeled using the Darcy-Forchheimer model.
For high-lift devices:
Low noise slat tracks and slat porous inserts
14 generic and low noise slat tracks have been acoustically assessed in Sep 21 in AWT@NLR on the flapless 2.5D high-lift wing F16 with a 30° sweep, showing the critical acoustic role of the wing cavity, and the potential of several low noise designs.
In parallel, a preliminary study of porous inserts (Diamond-Lattice cells and polyurethane foam) implemented at the slat suction side of the same model (but 0° sweep) has been achieved in AAWT@UoB in Oct 21. Their space-time features had been characterized in WAABLIEF@VKI to calibrate/validate numerical models implemented in the CFD solvers used in ongoing computations.
In April-May 22, the flow and noise of the same 14 slat tracks and all porous slats (with more inserts with new materials located close to the slat trailing edge) have been assessed in F2@ONERA on the full 3-element F16 model with a 30° sweep, either with the continuous slat configuration or with new inner/outer slat side-edges. Static pressure and PIV maps have been provided to 4 partners undertaking numerical simulations of slat tracks flow/noise. Their noise prediction at the positions of the 120-microphone array in F2 will be compared to experimental data.
Spoiler flow and noise have been extensively assessed in May-June 22 at AWT@UoS on a generic modular wall-mounted spoiler inclined to free stream. All broadband noise source mechanisms have been studied (deflection angle, upstream boundary layer and separation bubble, turbulent wake and side edge vortices). In parallel, numerical simulations with ProLB are under progress on this configuration. In a second step, ProLB will be applied to a more realistic spoiler configuration tested in AWB (OPENAIR).
The Krüger slat noise assessment now relies on the INTONE database, a German project in which one classic slat and two Krüger slat (reference/low noise) configurations were tested on the 3DFNGY model in NWB. CAD and flow conditions of these geometries were provided to 2 partners who achieve flow/noise numerical simulations, with ProLB and STAR-CCM+.
Several specification activities have started in WP5, in which all studied technologies will be assessed on two full generic aircraft models in NWB@DNW, one SMR transport aircraft and one BJ aircraft.
The overall impact of INVENTOR is expected to be twofold:
• Direct contributions to
o the unmatched short-term EU 2020 and middle-term 2050 objectives on reducing the noise generated by LGs and of HLDs through the development of innovative designs and NRTs,
o the 3rd objective of the EC Specific Programme on “Smart, green and integrated transport”, namely to the “Global leadership for the European transport industry” by providing to industry a key-advance in a competitive market.
• Indirect contributions to
o the 1st objective of this Programme, which targets a “Resource efficient transport that respects the environment” with the explicit aim “to minimise transport's systems' impact on climate and the environment (including noise, air and water pollution)”,
o the very stringent WHO demands for the sake of citizens’ health, and to the 4th objective of this Programme, “to support improved policy-making which is necessary to promote innovation and meet the challenges raised by transport, including the internalisation of external costs, and the societal needs related to it”.
• Direct contributions to
o the unmatched short-term EU 2020 and middle-term 2050 objectives on reducing the noise generated by LGs and of HLDs through the development of innovative designs and NRTs,
o the 3rd objective of the EC Specific Programme on “Smart, green and integrated transport”, namely to the “Global leadership for the European transport industry” by providing to industry a key-advance in a competitive market.
• Indirect contributions to
o the 1st objective of this Programme, which targets a “Resource efficient transport that respects the environment” with the explicit aim “to minimise transport's systems' impact on climate and the environment (including noise, air and water pollution)”,
o the very stringent WHO demands for the sake of citizens’ health, and to the 4th objective of this Programme, “to support improved policy-making which is necessary to promote innovation and meet the challenges raised by transport, including the internalisation of external costs, and the societal needs related to it”.