Resistance and Propulsion

Transcription

1 MSc. Naval Architecture and Marine Engineering Resistance and Propulsion 0-0 Project Propeller Design with the Lifting Line Theory - Program PROPINFAC

2 Resistance and Propulsion Project Propeller Design with the Lifting Line Theory - Program PROPINFAC -. Objective The objective of the project is to design a propeller for a given ship. The design includes: a) The hydrodynamic design of the propeller: determination of the radial distribution of circulation for the propeller in an axisymmetric axial wake field; b) The geometric design to satisfy cavitation and mechanical strength criteria; c) The preparation of final smoothed blade geometry.. The propeller design with the lifting line theory: Program PROPINFAC The propeller design for a given ship data is carried out with the program PROPINFAC (IST). The executable file is available for use at MARETEC-IST. The general description of the method is dealt with in the lectures. A detailed description can be found in the original references. [-4]. The user guide of PROPINFAC is given in separate documents [4-5].

3 3. Tasks 3. Selection of ship powering data relevant for the design. 3.. Obtain propeller design conditions from program DESPPC: Design ship speed, propeller thrust, propulsive factors: Taylor wake fraction, thrust deduction and relative rotative efficiency Obtain main propeller data from preliminary propeller design in program DESPPC: Propeller number of blades, propeller diameter, propeller rate of rotation, required blade area ratio Obtain or estimate effective axial wake radial distribution on propeller plane. 3. Running PROPINFAC 3.. Preparation of input for LERBSNU: hydrodynamic design (the input description is given in the Annex A) 3.. LERBSNU execution Preparation of input for PROPFC: geometric design PROPFC execution Preparation of input for GEOSMOOTH: 3D propeller blade geometry Execution of GEOSMOOTH. 3.3 Preparation of a report with the results of the design calculations and the main conclusion on the propeller design. References [] Roma, R.J.S., Falcão de Campos, J.A.C., Aplicação do Método dos Factores de Indução ao Projecto de Hélices Propulsores Marítimos, MARETEC, IST. [] Gaspar, B.C., Definição do Contorno da Pá no Programa PROPFC, MARETEC/IST RT-FJ6-3, Novembro de 004. [3] Gaspar, B.C., Introdução das Secções NACA-66 ( a = 0. 8 ) no Programa PROPFC, Maio de 006. [4] Roma, R.J.S., Manual do Utilizador dos Programas LERBS, LERBSNU e PROPFC, MARETEC/DEM RT-RD0-3, Agosto de 997. [5] Gaspar, B.C., Manual do Utilizador dos Programas PROPFC e GEOSMOOTH, Maio de

4 Annex A: Input Description of Program LERBSNU with example IHD = Thrust coefficient given; = Power coefficient given ITDP = Circulation distribution given; = Pitch distribution given IPV = lightly loaded assumptions; = moderately loaded assumptions 5 N = Number of points on the lifting line 4 NB = Number of Blades.805 CT or CP ideal 0.00 XH Non dimensional hub radius JE Advance coefficient based on effective wake velocity 9 NFG or NFP Number of points where FG or FP is specified Non dimensional radii where FG or FP is defined FP at the NFP points; for FG only NFG- interior points 9 NX Number of points where the wake fraction is defined NX Non dimensional radii where the wake fraction is defined WT at the NX points Effective wake fraction (average) 4

5 'E'! Comment line PROPFC_input_description.txt 'DMODE= & IA3= & BSMODE='! Comment line.643! Propeller rotation rate (r.p.s.) 6.977! Propeller diameter (m) 8.606! Ship speed (m/s) 05.0! Fluid density (kg/m^3) 0.348! Effective wake fraction (average) ! Effective wake fraction at the standard radii ! Atmospheric pressure (Pa) 300.0! Vapour pressure (Pa)! Design mode (= Given shaft immersion; = Given expanded blade area ratio)! DBAR! Expanded blade area ratio (if IMODE=) 7.570! Shaft immersion (m) (if DMODE=; estimate if DMODE=) 0.80! Safety margin against bubble cavitation.500! Polinomial exponent for the blade contour (default value = ) 0.500! Exponent for the blade contour in outer sections (default value = 0.5)! IA3 variable: Mode for specifying coefficient A3 for DMODE= (= specified by the user;= found by program)! da3! Increment for systematic variation of A3. Only for IA3=. (default value = 0.) 3.000! Coefficient A3 (if IA3=: required value; if IA3=: initial value) 0! Rake Angle (º) 0! Skew angle (º) ! Propeller material density (kg/m^3) Page

6 PROPFC_input_description.txt ! Material admissible maximum tensile stress (Pa) 0.500! Chord at the blade tip (m) 0.009! Maximum blade thickness at the tip (m) 0.7! maximum thickness-to-chord ratio at the blade root! Type of blade sections (= Walchner/Gutsche; = NACA66 at ideal angle of attack; =3 NACA66 at bucket mid-point) ! Drag coefficient CD of blade sections at standard radii! Type of geometry output (= calculation radii; = given radii) 9! Number of radii ! Radii given Page