La caratterizzazione aerodinamica dell’ETR500

Presentazione sul tema: "La caratterizzazione aerodinamica dell’ETR500"— Transcript della presentazione:

1 La caratterizzazione aerodinamica dell’ETR500
GIORNATA CIFI AERODYNAMICS IN OPEN AIR Firenze 20 febbraio 2009 La caratterizzazione aerodinamica dell’ETR500 F. Cheli

2 AERODYNAMICS IN OPEN AIR
Benvenuto e presentazione del Progetto (Trenitalia - Ing. Emilio Maestrini) Il fenomeno della “proiezione del ballast” (Trenitalia – Ing. Luca Bocciolini) Le misure adottate da RFI (RFI – Ing. Mario Testa) L’aerodinamica del sottocassa (Politecnico di Milano – Prof. Daniele Rocchi) La sicurezza contro il vento laterale: la norma Cen 14067/6 e la TSI (Trenitalia – Ing. Gianpaolo Mancini) La caratterizzazione aerodinamica dell’ETR 500 (Politecnico di Milano – Prof. Federico Cheli) Lo studio della situazione meteo delle zone attraversate dalla linea AV Roma-Napoli (Università di Genova – Prof. Giovanni Solari) L’analisi del rischio sulla linea AV Roma – Napoli (Politecnico di Milano – Ing. Gisella Tomasini) Provvedimenti adottati da RFI e cenno alla situazione internazionale (RFI – Mario Testa) Conclusioni (Ing. Angelo Pezzati) 2 2

3 LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500
IL VENTO TRASVERSALE SUI VEICOLI FERROVIARI EFFETTI DEL VENTO TRASVERSALE: sicurezza di marcia (ribaltamento, svio) PARTICOLARMENTE CRITICO IN CONDIZIONI DI: elevata velocità improvvise variazioni dei carichi aerodinamici (uscita da gallerie, raffiche) elevati valori di accelerazione non compensata (curva) IL PROBLEMA E’ DI ESTREMA ATTUALITA’: normative europee, specifiche su questo tema, in fase di definizione su questo problema POLIMI farà al temine del meeting una proposta operativa

4 CWC – Critical Wind Curve
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 RICERCA EUROPEA SUL VENTO TRASVERSALE Normative e progetti Normative internazionali su treni: TSI: Technical Specification for interoperability – Cross wind EN Railway applications — Aerodynamics  Progetti internazionali: AOA: Aerodynamics in Open Air E’ NECESSARIO DEFINIRE LE CONDIZIONI LIMITE PER UN TRENO SOGGETTO A VENTO TRASVERSALE CWC – Critical Wind Curve

5 Responsabilità NORMATIVA EUROPEA TSI
L’attuale revisione di TSI, della quale è in corso il processo di approvazione, comporta responsabilità a carico dell’Operatore e del Gestore dell’Infrastruttura Responsabilità dell’Operatore: caratterizzare la propria flotta nei confronti del vento laterale Responsabilità del Gestore dell’infrastruttura: assicurare il permanere delle condizioni di sicurezza di marcia nelle condizioni di esercizio più critiche 5

6 NORMATIVA EUROPEA TSI Linea interoperabile Una linea è dichiarata interoperabile se equipaggiata con un sistema di protezione atto a garantire la sicurezza di circolazione dei treni interoperabili. Il mantenimento delle condizioni di sicurezza può avvenire: con riduzione locale e temporanea di velocità in presenza di venti superiori alle CWC installando protezioni nelle tratte di binario soggette a forti venti 6

7 Veicolo interoperabile
NORMATIVA EUROPEA TSI Veicolo interoperabile Un veicolo è dichiarato interoperabile se progettato e verificato in modo tale da garantire un livello di stabilità predefinito sotto l’effetto del vento laterale. Tale livello è definito, per mezzo di un set di curve di riferimento caratteristiche (CWC) Per differenti condizioni operative e differenti scenari é definita la velocità critica del vento in funzione della velocità del treno I valori delle curve di riferimento rappresentano i requisiti minimi che deve soddisfare il materiale rotabile 7

8 Introduzione al problema Prove in galleria del vento
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 INDICE Introduzione al problema Prove in galleria del vento Coefficienti aerodinamici CWC Conclusioni 8

9 Introduzione al problema
Perché il problema è critico per i treni ad alta velocità? Fy FD FL UT=30 m/s Vrel =275 km/h= 75 m/s arel =25° Vtreno=250 km/h Fy = 5 tons Vtreno=0 Fy =14 tons Vtreno=250 km/h 9

10 Introduzione al problema
La caratteristica del vento reale Il vento reale è turbolento ed è una funzione del tempo e dello spazio [s] Storia temporale del vento 10

11 Introduzione al problema
tempo [s] spazio [m] Il vento “visto” dal treno Il treno si muove con velocità V attraverso questo profilo spazio temporale velocità del vento assoluta u(t,x) UT velocità del vento “vista” dal veicolo in movimento UT 11

12 Le caratteristiche del vento relativo
Introduzione al problema Le caratteristiche del vento relativo UT [s] V =70 m/s= 250 km/h arel=25° UT =30 m/s=105 km/h Vrel=75 m/s= 275 km/h 12

13 Introduzione al problema
Le forze aerodinamiche Sul treno nascono delle forze aerodinamiche funzioni del tempo che dipendono da: velocità di avanzamento del veicolo Vtreno profilo del vento trasversale caratteristiche aerodinamiche del veicolo CFy Fy FD FL F [tons] Vtr=250 km/h arel =25° UT=30 m/s Vrel =275 km/h= 75 m/s [s] 13

14 Introduzione al problema
Critical wind curve CWC La CWC rappresenta la velocità limite del vento che porta il veicolo a superare I limiti della marcia in sicurezza Vtr Vtr= velocità treno U= velocità assoluta vento Vrel= velocità relativa bw= angolo di attacco relat. arel U Vrel Forze aerodinamiche Codice di simulazione multi-body 14

15 Introduzione al problema
Critical wind curve CWC La CWC rappresenta la velocità limite del vento che porta il veicolo a superare I limiti della marcia in sicurezza Safety index 15

16 Introduzione al problema
Critical wind curve CWC Ulim (velocità massima di raffica) funzione della velocità del treno e dell’angolo di incidenza del vento Vrel arel Vtr bw Le CWC dipendono: layout tracciato (rettilineo o curve con a.n.c.) caratteristiche statistiche del vento (intensità di turbolenza, lunghezza di scala integrale,..) tipo di veicolo (caratteristiche delle sospensioni, geometria, carico per asse, …) scenario (rilevato, viadotto, trincea,…) U 16

17 CWC media e banda di incertezza (Umedia  3 sCWC)
Introduzione al problema Calcolo delle CWC: Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 17 17

18 Introduzione al problema Prove in galleria del vento
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 INDICE Introduzione al problema Prove in galleria del vento Coefficienti aerodinamici CWC Conclusioni 18

19 Potenza massima installata
Prove in galleria del vento La galleria del vento del Politecnico di Milano 2 1 Potenza massima installata Dimensioni globali 1.5 50 x 15 x 15 [MW] [m] Sezione di misura Dimensioni Max Vel. [m/s] I=/u % Boundary layer (2) 14 x 4 18 < ± 2 % High speed (1) 4 x 4 60 < ± 0.2 % 19

20 La galleria del vento del Politecnico di Milano
Prove in galleria del vento La galleria del vento del Politecnico di Milano è stata accreditata per prove TSI tramite test su ICE2

21 Embankment standard alto 6m Single track ballast and rail
Prove in galleria del vento Scenari di riferimento Normativa TSI 2005 Embankment standard alto 6m Flat ground … Normativa CEN 2009 Single track ballast and rail

22 flat ground+ballast&rail rilevato TSI camera boundary layer e
Prove in galleria del vento Modello in scala 1:20 Scenari: viadotto standard rilevato camera boundary layer (Re= – ) Modello in scala 1:10 Scenari: flat ground flat ground+ballast&rail rilevato TSI camera boundary layer e high-speed (Re= – ) 22

23 Prove in galleria del vento Modello in scala 1:10
Flat ground con e senza ballast&rail Bilancia dinamometrica esterna Boundary layer test section Modello sospeso VENTO P Z X b Barra di collegamento 192 - Bilancia dinamometrica Rilevato TSI alto 6m Flat ground con rail High speed test section Boundary layer test section 23

24 Prove in galleria del vento Modello in scala 1:20
Bilancia dinamometrica interna CASSA CARRELLI Tipico rilevato italiano Tipico viadotto italiano 12.4m 2.5m 5.6m 3.3m 6m 6m 30° 24

25 Introduzione al problema Prove in galleria del vento
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 INDICE Introduzione al problema Prove in galleria del vento Coefficienti aerodinamici CWC Conclusioni 25

26 Coefficienti aerodinamici Modello in scala 1:10
ETR500 Flat ground con solo binario: confronto primo/secondo veicolo Wind Fz Mx This slide shows the aerodynamic coefficients measured on the ETR500 train with the flat ground scenario, in terms of comparison between the locomotive and the first trailer coach. In particular, the vertical force coefficient is shown on the left while the roll moment coefficient is shown on the right. It is possible to observe that the first vehicle shows its maximum value for angles of attack ranged between 50 and 55 degrees, while the second vehicle reaches its maximum at 90°. The trend found for the locomotive is typical of all the leading vehicles of a convoy and it is due to a transition from slender to bluff body behaviour. Moreover, figure on the right shows also that the first vehicle is characterized by a roll moment coefficient higher than that of the second vehicle for all angles of attack; moreover, if we consider the interesting range of angles of attack for the cross wind problem, that is tha range between 0 to 35°, we can observe that also the vertical force coefficient relative to the first vehicle is higher, in modulus, than the corresponding coefficients measured on the second vehilce. on the other hand, the values of the vertical force coefficient of the locomotive are higher than those of the trailer coach only in the interesting range of angles of attack for the cross wind risk, that is between 10°to 40°. As a consequence, the first vehicle is considered as the most critical in terms of risk of overturning and it is the only analysed in the TSI. 26

27 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Flat ground con solo binario: effetto Reynolds Wind Fz Mx This slide shows the aerodynamic coefficients measured on the ETR500 train with the flat ground scenario, in terms of comparison between the locomotive and the first trailer coach. In particular, the vertical force coefficient is shown on the left while the roll moment coefficient is shown on the right. It is possible to observe that the first vehicle shows its maximum value for angles of attack ranged between 50 and 55 degrees, while the second vehicle reaches its maximum at 90°. The trend found for the locomotive is typical of all the leading vehicles of a convoy and it is due to a transition from slender to bluff body behaviour. Moreover, figure on the right shows also that the first vehicle is characterized by a roll moment coefficient higher than that of the second vehicle for all angles of attack; moreover, if we consider the interesting range of angles of attack for the cross wind problem, that is tha range between 0 to 35°, we can observe that also the vertical force coefficient relative to the first vehicle is higher, in modulus, than the corresponding coefficients measured on the second vehilce. on the other hand, the values of the vertical force coefficient of the locomotive are higher than those of the trailer coach only in the interesting range of angles of attack for the cross wind risk, that is between 10°to 40°. As a consequence, the first vehicle is considered as the most critical in terms of risk of overturning and it is the only analysed in the TSI. 27

28 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Flat ground con e senza ballast and rail V1 V2 without train Wind Fz Mx The flat ground with ballast and rail reproduces, in correspondence of the underbosy zone, the same boundary conditions of the embankment scenario. This slide shows both the roll moment, on the left, and the vertical force coefficient, on the right, in terms of comparison between the embankment scenario and the FG with BAR. For the roll moment coefficient, the behaviour is the same than that observed with the flat ground without ballast and rail. Nevertheless, when considering the vertical force, it is possible to see that the red points, that represent the coefficients measured with the embankment, evaluated by making reference to the upstream wind velocity, are in good agreement with black points relative to the flat ground with ballast and rail, in the range of the angle of attack between 0 to 30°. These experimental results confirm that the vertical force coefficient is not very sensitive to the speed up effect but it is mainly influenced by the boundary conditions in the underbody zone. 28

29 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Rilevato alto 6m: sopravento vs sottovento Wind Fz Mx In this slide, the same coefficients are shown for the locomotive on the standard embankment, in terms of comparison between windward and leeward side. We can see that the main differences between the two configurations arise, for both the coefficients, at high angles of attack, while at low angles, both the coefficients seem not to be significant sensitive to the transversal position of the train on the embankment. 29

30 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco rilevato vs flat ground: Coeff. di momento al rollio Wind Fz Mx Rilevato V1 In this slide the roll moment coefficient measured on the the locomotive of the ETR500 train is shown in terms of comparison between the standard embankment (windward) and the flat ground configuration without ballast. In particular, the aerodynamic coefficients measured with the embankment have been calculated by making reference to the incoming wind speed measured in two different positions: the red points refer to the coefficients evaluated by adopting, as reference wind speed, the wind velocity in free stream, named V1, while the green points corresponds to the coefficients calculated using the wind speed measured over the embankment, named V2. This second procedure is adopted to account for the speed up effect associated to the infrastructure scenario. It is possible to observe that, at low yaw angles (up to 35°) that corresponds to the interesting range for the cross wind risk analysis, the roll moment coefficient evaluated by making reference to the wind speed measured over the track is very close to the corresponding coefficient measured on flat ground. This demonstrates that, in this range of angles of attack, the gap in the roll moment coefficient between flat ground and embankment can be substantially ascribed to the speed up effect associated with the geometry of the embankment. The practical outcome of this experimental result is that one can always use the flat ground coefficients, provided that the accelerated wind speed on top of the embankment is adopted as the reference one for the aerodynamic loads computation. At higher yaw angles, the aerodynamic behaviour of the train is very influenced by the combined geometry of the complete system (train and embankment) and the physical phenomenon can not be simply reduced to a corrective coefficient related to the speed up effect In any case, it must be remembered that, when dealing with high speed trains, the train itself generally experiences wind angles smaller than 30°, also for limit wind speeds. As a consequence, the correction proposed for small angles of attack can be considered a useful mean to perform risk analysis calculations of specific embankment scenarios, starting from flat ground coefficients measured in wind tunnel. V2 30

31 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco rilevato vs flat ground: Coeff. forza verticale V1 V2 without train Rilevato Wind Fz Mx On the other hand, if we consider the vertical force coefficient, we can observe that, up to 30°, the coefficient measured on flat ground is lower than that measured on embankment, also considering the wind speed on the top of the scenario. In our opinion, in this case, the gap between the two scenarios is due to the different boundary conditions in the underbody zone. 31

32 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Rilevato vs flat ground con Ballast&Rail Vref 2m sopra il binario Wind Fz Mx Vref Vena libera The flat ground with ballast and rail reproduces, in correspondence of the underbosy zone, the same boundary conditions of the embankment scenario. This slide shows both the roll moment, on the left, and the vertical force coefficient, on the right, in terms of comparison between the embankment scenario and the FG with BAR. For the roll moment coefficient, the behaviour is the same than that observed with the flat ground without ballast and rail. Nevertheless, when considering the vertical force, it is possible to see that the red points, that represent the coefficients measured with the embankment, evaluated by making reference to the upstream wind velocity, are in good agreement with black points relative to the flat ground with ballast and rail, in the range of the angle of attack between 0 to 30°. These experimental results confirm that the vertical force coefficient is not very sensitive to the speed up effect but it is mainly influenced by the boundary conditions in the underbody zone. 32

33 Coefficienti aerodinamici Modello in scala 1:20
ETR500 loco Viadotto (scala 1:20) vs flat ground (scala 1:10) Wind Fz Mx 33

34 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Validazione ETR500 come veicolo di riferimento con prove a CSTB Flat ground con B&R Pari numero di Reynolds Wind Fz Mx Re= Re= The flat ground with ballast and rail reproduces, in correspondence of the underbosy zone, the same boundary conditions of the embankment scenario. This slide shows both the roll moment, on the left, and the vertical force coefficient, on the right, in terms of comparison between the embankment scenario and the FG with BAR. For the roll moment coefficient, the behaviour is the same than that observed with the flat ground without ballast and rail. Nevertheless, when considering the vertical force, it is possible to see that the red points, that represent the coefficients measured with the embankment, evaluated by making reference to the upstream wind velocity, are in good agreement with black points relative to the flat ground with ballast and rail, in the range of the angle of attack between 0 to 30°. These experimental results confirm that the vertical force coefficient is not very sensitive to the speed up effect but it is mainly influenced by the boundary conditions in the underbody zone. 34

35 Coefficienti aerodinamici Modello in scala 1:10
ETR500 loco Validazione ETR500 come veicolo di riferimento con prove a CSTB Flat ground con B&R Effetto numero di Reynolds Wind Fz Mx The flat ground with ballast and rail reproduces, in correspondence of the underbosy zone, the same boundary conditions of the embankment scenario. This slide shows both the roll moment, on the left, and the vertical force coefficient, on the right, in terms of comparison between the embankment scenario and the FG with BAR. For the roll moment coefficient, the behaviour is the same than that observed with the flat ground without ballast and rail. Nevertheless, when considering the vertical force, it is possible to see that the red points, that represent the coefficients measured with the embankment, evaluated by making reference to the upstream wind velocity, are in good agreement with black points relative to the flat ground with ballast and rail, in the range of the angle of attack between 0 to 30°. These experimental results confirm that the vertical force coefficient is not very sensitive to the speed up effect but it is mainly influenced by the boundary conditions in the underbody zone. 35

36 Coefficienti aerodinamici Modello in scala 1:10
ETR500 è veicolo di riferimento Confronto con ICE3 e TGV Rilevato Wind Fz Mx Flat ground The flat ground with ballast and rail reproduces, in correspondence of the underbosy zone, the same boundary conditions of the embankment scenario. This slide shows both the roll moment, on the left, and the vertical force coefficient, on the right, in terms of comparison between the embankment scenario and the FG with BAR. For the roll moment coefficient, the behaviour is the same than that observed with the flat ground without ballast and rail. Nevertheless, when considering the vertical force, it is possible to see that the red points, that represent the coefficients measured with the embankment, evaluated by making reference to the upstream wind velocity, are in good agreement with black points relative to the flat ground with ballast and rail, in the range of the angle of attack between 0 to 30°. These experimental results confirm that the vertical force coefficient is not very sensitive to the speed up effect but it is mainly influenced by the boundary conditions in the underbody zone. 36

37 Introduzione al problema Prove in galleria del vento
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 INDICE Introduzione al problema Prove in galleria del vento Coefficienti aerodinamici CWC Conclusioni 37

38 CWC media e banda di incertezza (Umedia  3 sCWC)
Calcolo delle CWC Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 38 38

39 Caratteristiche del vento turbolento
Calcolo delle CWC: definizione del vento Caratteristiche del vento turbolento Storia temporale del vento Profilo di velocità Tipo di terreno z0 [m] Iu [%] I. Mare aperto 0.001 0.05 II. Aperta campagna 0.13 III. Aree boscose, piccole città 0.15 0.24 IV. Aree centrali di grandi città 0.5 0.44 39

40 Caratteristiche del vento turbolento
Calcolo delle CWC: definizione del vento Caratteristiche del vento turbolento Indice di turbolenza Von Karman PSD Funzione di coerenza spaziale Lunghezza di scala integrale 40

41 Definizione della storia temporale della velocità del vento
Calcolo delle CWC: definizione del vento Definizione della storia temporale della velocità del vento Tipo di terreno Z0 41

42 Definizione della velocità del vento vista dal punto mobile
Calcolo delle CWC: definizione del vento Definizione della velocità del vento vista dal punto mobile tempo [s] spazio [m] [m/s] Velocità del vento assoluta u(t,s) UT(t) velocità del vento di un punto di riferimento che si muove con il veicolo Poichè il vento è un fenomeno random, partendo dalle stesse proprietà statistiche è possibile generare infinte storie temporali 42

43 CWC media e banda di incertezza (Umedia  3 sCWC)
Calcolo delle CWC: calcolo ammettenza Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 43 43

44 Ammettenza aerodinamica misurata sperimentalmente
Calcolo delle CWC: calcolo ammettenza Ammettenza aerodinamica misurata sperimentalmente 44

45 Ammettenza aerodinamica
Calcolo delle CWC: calcolo ammettenza Ammettenza aerodinamica Permette di tener conto della correlazione spaziale della distribuzione di velocità del vento tra due punti qualsiasi della superficie del veicolo in condizioni di vento turbolento La funzione di ammettenza può essere valutata: sperimentalmente, mediante prove in galleria in condizioni di vento turbolento numericamente, mediante un modello sviluppato sulla base della teoria di Cooper 45

46 CWC media e banda di incertezza (Umedia  3 sCWC)
Calcolo delle CWC: calcolo delle forze aerodinamiche Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 46 46

47 U Definizione delle forze aerodinamiche: effetto della turbolenza
Calcolo delle CWC: calcolo delle forze aerodinamiche Definizione delle forze aerodinamiche: effetto della turbolenza TEORIA QUASI STATICA CORRETTA TEORIA QUASI STATICA V V U UT(t) V Vrel_TC è la velocità corretta con la funzione di ammettenza Vrel_TC UTC brel Vrel UT 47

48 CWC media e banda di incertezza (Umedia  3 sCWC)
Calcolo delle CWC: calcolo risposta dinamica veicolo Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 48 48

49 Modello MB di simulazione dinamica
Calcolo delle CWC: calcolo delle forze aerodinamiche Modello MB di simulazione dinamica Caratteristiche: marcia in rettilineo/curva effetti non lineari associati alle sospensioni (tamponi,…) reali profili di contatto irregolarità binario 49

50 CWC media e banda di incertezza (Umedia  3 sCWC)
Calcolo delle CWC: calcolo risposta dinamica veicolo Metodologia stocastica numerico-sperimentale CWC media e banda di incertezza (Umedia  3 sCWC) 2. Definizione del vento turbolento 1. Test galleria del vento 5. CWC CFy 3. Funzione di ammettenza This slide shows the flow chart of the stochastic methodology: In the first part, by wind tunnel tests the aerodynamic coefficients are evaluated. In the second part, starting from the cross wind characteristics, by the wave superposition method, the absolute wind velocity as a function of the time and the space is defined. The third step leads to the calculation of the wind dynamic loads according to an algorithm based on the vehicle admittance. As said before, this algorithm accounts for the actual turbulent wind speed distribution as a function of space and time, for the vehicle’s geometry and for its operating conditions. Finally, the dynamic loads are the input for the MB model that allows to evaluate the dynamic response of the rail vehicle subjected to real turbulent wind conditions. By processing the output of the numerical simulation, it’s possible to define the limit safety conditions of the vehicle in terms of critical wind curves It is important to note that, because the wind-train interaction is a random process, with the POLIMI method the CWC are defined by a statistic approach in terms of mean CWC and corresponding spread band. This is due to the fact that starting from the same wind properties (mean speed, turbulence intensity, integral lenght scale, PSD and coherence function) it possible to define different wind speed time-histories, all characterised by the same wind scenario. Forze aerodinamiche F(t,x,y,z) 4. Modello multi body della dinamica del veicolo 50 50

51 Indici di sicurezza: definizioni
Calcolo delle CWC Indici di sicurezza: definizioni Qup carico verticale ruota sopravento Ribaltamento (filtro 2 Hz) Qdown carico verticale ruota sottovento Qup0 carico verticale ruota statico Scarico ruota (filtro 2 Hz) Proud’homme Svio (non significativo) 51

52 Schema CWC Calcolo delle CWC Forza aerodinamica
Modello multibody del veicolo Forze verticali di contatto Calcolo indici di sicurezza CWC 52

53 Definizione della CWC U=U1 CWC U=U2 V=V Calcolo delle CWC
Coefficiente di scarico ruota U=U1 CWC U=U2 V=V 53

54 Fisse caratteritiche del vento Fissato veicolo – scenario – vento
Calcolo delle CWC STOCHASTIC APPROACH Definizione della distribuzione di CWC Fisse caratteritiche del vento CWCs Fissato veicolo – scenario – vento CWC media e BANDA di incertezza Differenti storie temporali Varying the random phase in the generation of wind speed time history, it is possible to obtain different time-history of aerodynamic loads and, as a consequence, different CWCs. Because the wind is a random process, it would be necessary to apply a statistical approach also in the calculation of CWC, by repeating the overall procedure for the same input data but with different values of random phases, in order to determine ‘mean’ CWC and the corresponding spread band. In order to reproduce the real statistical beahaviour of vehicle, it would be necessary to performed different simulations in order to get to a mean CWC and to the corresponding spread band. A similatr approach is applied in the vehicle dynamic study “statistical evaluation” in order to take into account of the track irregularity (UIC 518) random process. (statistica a posteriori) 54

55 CWC ETR500 Scenario flat ground Rettilineo Curva aq=1 m/s2 55

56 Scenario flat ground V= 300 km/h
CWC ETR500 Scenario flat ground V= 300 km/h 56

57 Introduzione al problema Prove in galleria del vento
LA CARATTERIZZAZIONE AERODINAMICA DELL’ETR500 INDICE Introduzione al problema Prove in galleria del vento Coefficienti aerodinamici CWC Conclusioni 57

58 galleria del vento italiana accreditata ETR500 treno accreditato TSI
CONCLUSIONI galleria del vento italiana accreditata ETR500 treno accreditato TSI messa a punto metodologia stocastica italiana utilizzo della metodologia per analisi rischio linea utilizzo della metodologia come ausilio progettazione linee metodologia stocastica attualmente inserita tra i metodi utilizzabili per il calcolo delle CWC all’interna della nuova normativa CEN sul vento trasversale crescita di un team RFI, Trenitalia, Unige, PoliMi che deve continuare ad essere presente a livello europeo proposta PoliMi …… 58

59 AERODYNAMICS IN OPEN AIR
Benvenuto e presentazione del Progetto (Trenitalia - Ing. Emilio Maestrini) Il fenomeno della “proiezione del ballast” (Trenitalia – Ing. Luca Bocciolini) Le misure adottate da RFI (RFI – Ing. Mario Testa) L’aerodinamica del sottocassa (Politecnico di Milano – Prof. Daniele Rocchi) La sicurezza contro il vento laterale: la norma Cen 14067/6 e la TSI (Trenitalia – Ing. Gianpaolo Mancini) La caratterizzazione aerodinamica dell’ETR 500 (Politecnico di Milano – Prof. Federico Cheli) Lo studio della situazione meteo delle zone attraversate dalla linea AV Roma-Napoli (Università di Genova – Prof. Giovanni Solari) L’analisi del rischio sulla linea AV Roma – Napoli (Politecnico di Milano – Ing. Gisella Tomasini) Provvedimenti adottati da RFI e cenno alla situazione internazionale (RFI – Mario Testa) Conclusioni (Ing. Angelo Pezzati) 59 59