A practical technique for improvement of open water propeller performance

S. Bal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


A practical technique for the improvement of open water propeller performance has been described by using a vortex lattice lifting line method together with a lifting surface method. First, the optimum circulation distribution, giving the maximum thrust-torque ratio, has been computed along the radius of the propeller for given thrust and chord lengths, by adopting a vortex lattice solution to the lifting line problem. Then, by using the lifting surface method, the blade sectional properties such as pitch-to-diameter ratio and camber ratio, have been calculated for obtaining the desired circulation distribution. The effects of skew and rake on propeller performance have been ignored. The blades have been discretized by a number of panels extending from hub to tip. The radial distribution of bound circulation can be computed by a set of vortex elements having constant strengths. Discrete trailing free vortex lines are shed at each panel boundary, and their strengths are equal to the differences in strength of the adjacent bound vortices. The vortex system has been built from a set of horseshoe vortex elements, and they consist of a bound vortex segment and two free vortex lines of constant strengths. Each set of horseshoe vortex elements induces an axial and tangential velocity at a specified control point on the blades. An algebraic equation system can be formed by using the influencial coefficients. Once this equation system has been solved for unknown vortex strengths and specified thrust, the optimum circulation distribution and the forces can be computed by using Betz-Lerbs method. When the radial distributions of optimum circulation (loading) and chord lengths have been reached, the lifting surface method can be applied to determine the blade pitch and camber distribution. DTMB 4119 and DTMB 4381 propellers have been adopted for calculations and their hydrodynamic characteristics have been found in their open literature. A very good comparison has been obtained between the results of this practical technique and the experimental measurements.

Original languageEnglish
Pages (from-to)375-386
Number of pages12
JournalProceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment
Issue number4
Publication statusPublished - Nov 2011


  • Betz-Lerbs condition
  • Lifting line method
  • Lifting surface method
  • Optimum ship propeller
  • Propeller analysis
  • Propeller design
  • Vortex lattice method


Dive into the research topics of 'A practical technique for improvement of open water propeller performance'. Together they form a unique fingerprint.

Cite this