MATEC Web of Conferences 4, 0100 (018) https://doi.org/10.1051/atecconf/01840100 BulTrans-018 Modeling of aircraft jet noise in airports Hristina Georgieva 1, rasin Georgiev 1 Technical University Sofia, Mechanical Departent, 1756 Sofia, 8 lient Ohridski Blvd., Bulgaria Technical University Sofia, Aeronautical Departent, 1756 Sofia, 8 lient Ohridski Blvd., Bulgaria Abstract. A atheatical odel with 4 ree of freedo created in Matlab for aircraft final landing trajectory is described in this paper. A idsize coercial passenger aircraft siilar to an Airbus A0 has been chosen as a reference aircraft. The paraeters of odel are obtained fro Airbus, Eurocontrol and the approach procedure at the airport is selected up fro Jeppesen Airway anual. A sei-epirical odel of Stone for predicting the jet noise has been used. The proposed odel was validated against 10 real flights obtained fro Aircraft noise onitoring at airport. The coputed error between the real data and odelling is reported on. Obtained results are presented nuerical and graphically. The observed effects of aircraft speed, aircraft angle of descent and aircraft weight for reduction of aircraft jet noise in airports represent subjects of discussions in the paper. 1 Introduction Conteporary society is difficult to iagine without the air transport and related iproveents, facilitating everyday life. It causes noise pollution of the environent, which is considered today to be one of the ost significant environental proble affecting population and the environent. The aircraft noise is highest on the airports and counities around airports. It can lead to counity annoyance, sleep disturbance and could increase the risk of high blood pressure, heart disease, heart attack for people living near airports. Significant research is currently being undertaken with the goal of reducing aircraft noise [1]. The Environental Noise Directive (END) [] is the legislative instruent at European Union (EU) under that environental noise is onitored and necessary actions (standards and recoended) nors are taken. To reduce the noise levels in airports and place close to the airports the Directive applies noise criteria for noise apping, developing and iplanting action plants. The theoretical odels allow predicting and anaging the real object. There are two types of odels. The theoretical odels of the first group are based on epirical data and use specialized software products [, 4]. This work is focused on the second type of odels that use the basic principles of aircraft odelling. They represent the aircraft as a point-ass odel including the aerodynaics of the aircraft itself. The differential equations describe the aircraft position in space and allow finding an appropriate relationship between the investigated paraeters. They allow the optiization of aircraft trajectories and deterination also of noise level fro these trajectories. The odels that are used in the literature are with 4 to 6 rees of freedo [5, 6, 7]. hardi and Abdallah propose a 4-ree odel of aircraft [5] siulating the final trajectory of landing. In their work they use two approaches for iniization of aircraft jet noise. The first one suggests a constant throttle setting and variation of angle descent between 0 and 4.5. The second one defines two stages of throttle section which variation is between 0 and 0.6 and the angle of descent also varies between 0 and 4.5. Menendez describes an aircraft odel [6] with 6 rees of freedo for evaluation of aircraft noise abateent procedures. He is focused on the ore flexible trajectories which will enable the definition of optial flight procedures regarding the noise annoyance ipact, especially in the arrival and departure phases of flights. In work [7] the noise reduction is obtained as coupling the aircraft nose. The two siilar coercial aircraft are supposed to land successively on one runway without conflict. The aircraft oveent of the two aircrafts is presented by atheatical odel with 6 rees of freedo. While aintaining an evolution of the flight approach procedures the sae optial trajectory has been achieved for the two-aircraft even though the procedures are different. oenig et al. [8] describe the increase of the aircraft angle of descent to reduce the noise level without necessity of flight procedure change. In the above odels the sei-epirical odel of Stone [] is used to predict the engine jet noise level for single and ixed dual jets up to bypass ratios of 15 as the ain source. In general, the odel can be applied to subsonic or supersonic flights up to Mach nubers of.5. J. E. Bridges et al. [10] analyse the ethod and prove its applicability to odern engines with a high bypass ratio. The ain sources of aircraft noise are the engine and its body. In the current work a atheatical odel with 4 ree of freedo created in Matlab is described. It includes two sections. The first presents the odelling of aircraft final landing trajectory and the second one the odelling of engine jet noise level. The odel perits to Corresponding author: hgeorgieva@tu-sofia.bg The Authors, published by EDP Sciences. This is an open access article distributed under the ters of the Creative Coons Attribution License 4.0 (http://creativecoons.org/licenses/by/4.0/).
MATEC Web of Conferences 4, 0 100 (018 ) BulTrans-018 https://doi.org/10.1051/atecconf/01840100 are taken the geoetric paraeters [11]. The aircraft altitude, aircraft speed and the engine thrust setting deterine the engine operation. According to the engine operation, specific engine therodynaic paraeters have to be generated. To calculate the paraeters of abient condition it has been used the International Standard Atosphere (ISA) [15]. The required specific design paraeter of the engine for priary and secondary flow a turbofan calculator is used [16, 17]. investigate different variants of aircraft landing trajectories for reducing the aircraft jet noise level in airports through the variation of angle of descent, velocity of descent and aircraft weight. Hence it has been proposed a coplete ethod for reducing the aircraft jet engine noise, including all the possible coponents on which it depends. Methodology of data selection Table. Engine noise odelling data..1 For odelling of aircraft landing trajectory Data fro The aircraft chosen for the siulation is siilar to the Airbus A0 which is widely used for short to ediu range flights [11]. According to perforance training anual of Airbus [1] the aircraft velocity of descent varies fro 8 to 118. Data for odelling of aircraft landing trajectory on airport (Fig. 1) is taken fro the Jeppesen Airway anual [1]. Engine Abien condition Fig. 1. Runway ap of airport. In Table 1 is shown the selected paraeters: the runway altitude, altitude of descent and the angle of descent. This aircraft is equipped by two types of engines: CFM565A and V57A. According the data fro Eurocontrol [14] widely used is CFM565A engine. This engine develops a axiu thrust force of 118 kn (Table 1). Aircraft Runway Engine Paraeter Max landing weight, MTLW Wing span, b Wing are, S Wing aspect ratio, A Sweeper angle, χ Velocity of descent, V Runway altitude, hrunway Altitude of descent, h Angle of descent, γ Thrust, T Thrust specific fuel consuption, tsfc 64500 5.8 1.6.5 5 8-116 48 00 118.4444 10 5 s 1. 1.8 Function of D1 Function of D 45 1-5 0 77-11 86 0811.7 8.06 1.11 6.766 0.1 Pa kg/ Modelling of aircraft landing trajectory and jet engine noise The proposed odel includes sections..1 Modelling the aircraft landing trajectory Table 1. Aircraft landing trajectory odelling data. Data fro Paraeter Hydraulic diaeter of inner contour, D1 Hydraulic diaeter of outer contour, D Nozzle area of inner contour, A1 Nozzle area of outer contour, A Polar angle, α Jet velocity in inner contour, v Flow velocity in outer contour, v1 Jet teperature in inner contour, T Flow teperature in outer contour, T1 Flow pressure, p Flow teperature, T Flow density, ρ Sound speed, c Mach nuber, M Fig. shows the aircraft odel used in this study and the aircraft landing trajectory. kg kn N/sN Fig.. Aircraft landing trajectory For the differentials equations (1) describing the aircraft landing trajectory is valid the following fourdiension syste derived at the aircraft centre of ass:. For odelling of jet engine jet noise The engine jet noise odel requires specific input data with respect to geoetry and operational conditions of the selected engine (Table ). Fro the Airbus technical data
MATEC Web of Conferences 4, 0 100 (018 ) BulTrans-018 https://doi.org/10.1051/atecconf/01840100 x V cos ; h V sin ; where v is the effective jet speed defined as: (1) T D V g sin ; tsfct, 1 M M ; () Str f Tt, T t, 1 M cos 0.4 1 cos (8) cos cos 0.0158 v v c v 0.0158 c 1.1 A1 A for A1 A.7 6.0 for A1 A.7 0.5 () where the exponent is defined as a function of the area ratio: c 141.0 10 log10, ISA c,isa 0.4 Tt, Lc jet 5 log 10 Tt,1 1 A1 v1 (10) A v v 10 log 101 1 1. v A1 1 A (7) ΔLc jet is defined as: Lnor is a noralized sound pressure level and it is defined according to the nozzle geoetry and the operating condition. v V cos c cor v c 0.1 L jet Lnor Ldir / spec Strc jet, cor Lc jet () 15 log10 1 M con cos (6) with αcor is a corrected directivity angle defined as: The jet noise consists of three principal coponents: turbulent ixing noise, broadband shock associated noise and screech tones. The jet noise is approxiately onidirectional during the descent phase and the noise levels decrease as speed decreases when assuing that the thrust is constant. It is extreely coplex to predict the jet noise. In this work to odel the aircraft engine jet noise is used a sei-epire odel of Stone [].The odel assues a syetric noise eission with respect to the engine reference axis. v 75 log10 c 0.04M con 4 A D 4A v 1 0.6 v v c 1 0.6 v c. Modelling of aircraft engine jet noise A 10 log10 10 log10 d 1 Str is an effective Strouhal nuber. with T0 the full thrust, δx the throttle setting, ρ the density of air at altitude, ρ0 the density of air at ground, M the Mach nuber, S the wing span, CZα the gradient of the lift depends on the high lift device, Cx0 the drag coefficient for α=0, ki the induced drag coefficient, c the speed of sound at the altitude h [18]. Lnor 0.6 v c.5 M con 0.6 1 D SV C x 0 k i C Z ; V M, c.0v c.5 Mαcon is a convective Mach nuber: (5) ω is the exponent applies to hot jets: where (x, h) are the position of the aircraft, (V, γ) are respectively the velocity and the angle of the descent. The variables (Т, tsfc, D, and g) are respectively the engine thrust, thrust specific fuel consuation, the drag force, the aircraft weight and gravity acceleration. Those variables are expressed as: T T0 x 0 V v v 1 cos v (11) 4 Results and discussion (4) An option which has to be evaluated in order to reduce the engine jet noise level in airports is the aircraft angle of descent. In this work is considered an aircraft landing which odel uses the following reference values [16] for: A 10 log10 1 M cos log10 0.5, D
MATEC Web of Conferences 4, 0 100 (018 ) BulTrans-018 https://doi.org/10.1051/atecconf/01840100 angle of descent γ = ; velocity of descent V = 67 ; noinal weight = kg. The landing duration is 140 s. The throttle setting δx is constant during the landing. Graphics and nuerical results are obtained fro the proposed odel. Fig. shows the siulated aircraft landing trajectory for different angle of descent γ which varies between.8 and.4 and different velocity of descent V which varies between 5 and 67. Matheatical odelling is a odern research tool, but only when the proposed odel is validated. To validate the calculated noise level of the aircraft jet engine it has been used experiental data fro ten real flights (Table 4, Fig. 5) fro Aircraft noise onitoring syste at airport (Fig. 4). The syste operates currently with 16 stationary easuring stations which are positioned at a radius of soe 0 k around the airport. Additionally three obile easureent stations are also used at places where no stationary easuring station provides inforation about aircraft noise pollution [1]. Fig.. Results fro the siulated aircraft landing trajectory. Fig. 4. Noise onitoring syste at airport. Table 4: Data fro the easureent station NMT7 at airport runway 08L/6R on 0.04.018 and angle of descent γ =. Table shows the nuerical values for calculated aircraft engine jet noise levels fro the odel for: different value of angle of descent γ; different velocity of descent V. Table. Obtained nuerical value fro the jet engine odel. 1 Para. Angle Weight Speed Noise.0 67 7.6.8.54. 60 70.8.4 5 6.88.0 64000 67 75.08 kg 4 As can be seen in table, according to the odel: at a reference angle of descent γ = and a reference velocity of descent V = 67, the obtained level of aircraft jet engine noise is 7.60 ; at an angle of descent γ =.8 and a velocity of descent V =, the noise level fro the aircraft jet engine increases as copared to the reference angle by 0. ; at an angle of descent γ =. and a velocity of descent V = 60, the noise level fro the aircraft jet engine decreases as copared to the reference angle by 1.65; at an angle of descent γ =.4 and a velocity of descent V = 5, the noise level fro aircraft jet engine aircraft decreases as copared to the reference angle by.75. Obviously, the results show that there is a trend to reduce the aircraft jet noise after changing the angle of descent γ and velocity of descent V. Larger variations in descent angle γ and velocity of descent V are liited by the difficulties of change in the landing procedure. When the aircraft landed, it spent uch of its fuel and the weight of the passengers and baggage in the cargo copartent stays constant. Thus study with changing the aircraft weight is not necessary. However soeties iediately after the aircraft takes-off, there is an eergency situation (incident) that causes an unplanned landing. In this cause the aircraft has a axiu landing weight. The odel perits to calculate the noise level in this case also (Table ). 5 6 7 8 10 Flight DublinEI 5 HanoverLH 0 BerlinLH 0 FrankfurtLH 100 Pala de DE Majorca150 MoscowSU BerlinEZY 5665 LondonLH 4 ievlh 545 BerlinLH 047 Speed Noise 66 6 7 7 78 7 80 70 71 75 8 77 5 7 Fig. 5. Obtained results fro the engine noise fro the odel and the real flight fro the airport onitoring syste. The average deviation in the results fro the jet engine odel with the data fro noise onitoring syste is 1.1 %. 4
MATEC Web of Conferences 4, 0 100 (018 ) BulTrans-018 https://doi.org/10.1051/atecconf/01840100. J. Stone, D. Groesbeck, C. Zola, Conventional profile coaxial jet noise prediction, AIAA Journal, 1(1), 6-4 (18) 10. J. Bridges, A. havaran, C. Hunter, Assessent of current jet noise prediction capabilities, 14th Aeroacoustics Conference, Vancouver, Canada, May 5-7 (008) 11. Airbus-AC-A0, Aircraft Characteristics - Airport And Maintenance Planning. AIRBUS S.A.S. Custoer Services, Technical Data Support and Services, 1707 Blagnac Cedex, France (016) 1. Airbus, Training&Flight Operation support and services, Flight crew perforance course, A18/A1/A0/A1, Perforance Training Manual, 1707 Blagnac Cedex, France (005) 1. http://ww1.jeppesen.co/personalsolutions/aviation/vfr-charts.jsp (0.07.018) 14. https://www.aircraftnoiseodel.org/ (0.07.018) 15. https://www.digitaldutch.co/atoscalc/ (0.07.018) 16. D. Adolfo, D. Bertini, A. Gaannossi, et C. Carcasci, Therodynaic analysis of an aircraft engine to estiate perforance and eissions at LTO cycle, 7nd Conference of the Italian Theral Machines Engineering Association, ATI017, 6-8 Septeber, Lecce, Italy (017) 17. https://www.particleincell.co/014/turbofancalculator/ (0.04.018) 18. A. Bos, Aircraft perforance suary tables for the base of aircraft data (BADA) revision.0. EEC Technical / Scientific Reports 1. https://travis-web01.unichairport.de/data/travis.php?lang=en&_ga=.4108178. 1856868.15457787-14088401.151440516 (0.04.018) 5 Conclusion A ain source of noise fro a low fly-over aircraft in the airports is its engine. In this work for siulating the aircraft landing trajectory is used: aircraft Airbus A0 widely used for short to ediu range flights equipped with two CFM565A engines and runway of airport which is one of the busiest airport in Europe. The suggested odel: is validated; shows graphical and nuerical results; allows to study different possibilities of reducing the aircraft jet the noise level during landing in airports; allows to calculate the aircraft jet noise level in eergency situations; no coplicated atheatical ethods which reduces the calculation tie; is general and gives the possibility to investigate the reduction of jet engine noise on aircraft equipped with engine without ixing flows. In the future, the research will focus on creating a odel to investigate the noise level of airfrae and the engine odel will be developed by adding the fan noise. This work has been supported by Research and Scientific Centre of Technical University of Sofia (Grand 181ПР001-04). References 1. http://www.futuresky.eu/projects/noise (0.07.018). EC, 00, Directive 00/4/EC of the European Parliaent and of the Council of 5 June 00 relating to the assessent and anageent of environental noise, OJ L 1, 1-5 (18.7.00). Е. Boeker, E. Dinges, B. He, G, Fleing, C. Roof, P. Gerbi, A. Rapoza, J. Herann, Integrated noise odel (INM) version 7.0 technical anual, FAA-AEE-08-01 (008) 4. W. rebs, Sound source data for aircraft noise siulation, Acta Acoustica united with Acustica, 0(1), 1-100 (004) 5. S. hardi, L. Abdallah, Optiization approaches of aircraft flight path reducing noise: Coparison of aircraft odelling ethods, Applied Acoustics,, 1-01 (01) 6. X. Menedez, Contributions to the optiisation of aircraft noise abateent procedures, Doctoral Thesis, Càtedra abertis de Gestión de Infraestructuras del Transporte Universitat Politècnica de Catalunya (011) 7. F. Nahayo at al., Optial control of two-coercial aircraft dynaic syste during approach, The Noise Levels Miniization. Gen. Math. Notes, (), 7-4, (011) 8. R. oenig, E. Schubert, On the influences of an increased ILS glide slope on noise ipact, fuel consuption and landing approach operation, AIAC14 Fourteenth Australian International Aerospace Congress, 8 February March, Melburn (014) 5