A method for optimum cavitating ship propellers

Şakir BAL

Makale detayları

A method for optimum cavitating ship propellers

Yazarlar:

Şakir BAL

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Engineering and Environmental Sciences 2011 Vol.35 Issue 3, pp.319-338

Belge Tipi:

Makale

Yayın Tarihi:

2/2011

Belge Dili:

Türkçe

Document ID (Org No.):

2000744647

Sıklık:

Üç Yıllık

eISSN:

1303-6157

pISSN:

1300-0160

Özet:

 

A practical design method was applied to obtain optimum  cavitating ship propellers by combining a vortex lattice lifting line  method (propeller design program) and a lifting surface method  (propeller analysis program).  The optimum circulation distribution  that gives the maximum lift-to-torque ratio was computed for given  thrust and given chord lengths along the radius of the propeller by a  vortex lattice solution to the lifting line problem.  The section  details of the blades, such as pitch-to-diameter ratio and camber  ratio, were then found to obtain the desired (optimal) circulation  distribution automatically by a lifting surface method.  In order to  get the optimum circulation distribution, the radius of the blades was  divided into a number of panels extending from hub to tip.  The radial  distribution of bound circulation could be computed by a set of vortex  elements that have constant strengths.  A discrete trailing free  vortex line was shed at each of the panel boundaries with strength  equal to the difference in strengths of the adjacent bound vortices.  The vortex system was built from a set of horseshoe vortex elements,  each consisting of a bound vortex segment of constant strengths and 2  free vortex lines of constant strengths.  An algebraic equation system  could be formed by using these vortex systems.  Once this equation  system for unknown vortex strengths was solved with a specified  thrust, the optimum circulation distribution and the forces could be  computed by the Betz-Lerbs method.  When the radial distribution of  optimum circulation and chord length were reached, the lifting surface  method could be applied to determine the blade pitch and camber in  order to produce the desired circulation automatically.  The lifting  surface method also accounts for cavitation, which is an avoidable  physical phenomenon on the blades.  The cavity effects in the present  method were represented by using cavity sources and cavitating  velocities, which were evaluated on the blade surface beneath the  cavity.  The practical design technique was applied both to  noncavitating and cavitating DTMB 4119 and DTMB 4381 propellers, for  which the hydrodynamic characteristics are given in the literature,  and the results were compared with those given in the literature.  A  very good level of satisfaction was obtained for practical  applications.

 

A practical design method was applied to obtain optimum  cavitating ship propellers by combining a vortex lattice lifting line  method (propeller design program) and a lifting surface method  (propeller analysis program).  The optimum circulation distribution  that gives the maximum lift-to-torque ratio was computed for given  thrust and given chord lengths along the radius of the propeller by a  vortex lattice solution to the lifting line problem.  The section  details of the blades, such as pitch-to-diameter ratio and camber  ratio, were then found to obtain the desired (optimal) circulation  distribution automatically by a lifting surface method.  In order to  get the optimum circulation distribution, the radius of the blades was  divided into a number of panels extending from hub to tip.  The radial  distribution of bound circulation could be computed by a set of vortex  elements that have constant strengths.  A discrete trailing free  vortex line was shed at each of the panel boundaries with strength  equal to the difference in strengths of the adjacent bound vortices.  The vortex system was built from a set of horseshoe vortex elements,  each consisting of a bound vortex segment of constant strengths and 2  free vortex lines of constant strengths.  An algebraic equation system  could be formed by using these vortex systems.  Once this equation  system for unknown vortex strengths was solved with a specified  thrust, the optimum circulation distribution and the forces could be  computed by the Betz-Lerbs method.  When the radial distribution of  optimum circulation and chord length were reached, the lifting surface  method could be applied to determine the blade pitch and camber in  order to produce the desired circulation automatically.  The lifting  surface method also accounts for cavitation, which is an avoidable  physical phenomenon on the blades.  The cavity effects in the present  method were represented by using cavity sources and cavitating  velocities, which were evaluated on the blade surface beneath the  cavity.  The practical design technique was applied both to  noncavitating and cavitating DTMB 4119 and DTMB 4381 propellers, for  which the hydrodynamic characteristics are given in the literature,  and the results were compared with those given in the literature.  A  very good level of satisfaction was obtained for practical  applications.

Makale detayları

A method for optimum cavitating ship propellers

Yazarlar: Şakir BAL

Yayıncı: TUBITAK

Dergi: Turkish Journal of Engineering and Environmental Sciences 2011 Vol.35 Issue 3, pp.319-338

Belge Tipi: Makale

Yayın Tarihi: 2/2011

Belge Dili: Türkçe

Document ID (Org No.): 2000744647

Sıklık: Üç Yıllık

eISSN: 1303-6157

pISSN: 1300-0160

Sayı

Yazarlar:

Şakir BAL

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Engineering and Environmental Sciences 2011 Vol.35 Issue 3, pp.319-338

Belge Tipi:

Makale

Yayın Tarihi:

2/2011

Belge Dili:

Türkçe

Document ID (Org No.):

2000744647

Sıklık:

Üç Yıllık

eISSN:

1303-6157

pISSN:

1300-0160