245mi - architettura navale · 2020. 12. 23. · 245mi - architettura navale a.a. 2020/21 propeller...
TRANSCRIPT
-
245MI - Architettura NavaleA.A. 2020/21
Propeller geometry
Docente: Prof. Mitja MorgutUniversità degli Studi di TriesteDipartimento di Ingegneria e ArchitetturaVia A. Valerio 10, 34127 TriesteEdificio C5 - Stanza C5_2.44mail: [email protected]
-
Geometry Airfoil Scale effects
Frames of reference
Architettura Navale, A.A. 2020/21
Global reference frame Local reference frame
-
Geometry Airfoil Scale effects
Propeller reference lines
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Cylindrical sections
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Pitch
Architettura Navale, A.A. 2020/21
Definition of helix Definition of pitch angle
-
Geometry Airfoil Scale effects
Pitch lines
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Mean pitch
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Skew
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Total rake (and the expanded view)
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Propeller outlines and area
Architettura Navale, A.A. 2020/21
Approximation: AD ≈ AE
-
Geometry Airfoil Scale effects
Example
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Example
Architettura Navale, A.A. 2020/21
-
Geometry Airfoil Scale effects
Airfoil
Architettura Navale, A.A. 2020/21
CL =L
0.5ρAV 2
CD =D
0.5ρAV 2
A = chord× span
-
Geometry Airfoil Scale effects
Propeller scale effects - 1978 ITTC performance prediction method
Architettura Navale, A.A. 2020/21
ReM(0.75R) =V0.75R c
νM
V =√
V 2A + (0.75πnD)2
KTS = KTM −∆KTKQS = KQM −∆KQ
∆KT =−0.3∆CD(
P
D
)(cZ
D
)∆KQ = 0.25∆CD
(cZ
D
)∆CD =∆CDM −∆CDS
∆CDM = 2(1+ 2t
c
)[0.044
(ReM(0.75R))1/6− 5
(ReM(0.75R))2/3
]
∆CDS = 2(1+ 2t
c
)[1.89+1.62log10
(c
Kp
)]−2.5
GeometryFrames of reference
AirfoilScale effects