Book contents
- Frontmatter
- Contents
- Preface
- Notation
- Abbreviations
- 1 Brief review of basic hydrodynamic theory
- 2 Properties of distributions of singularities
- 3 Kinematic boundary conditions
- 4 Steady flows about thin, symmetrical sections in two dimensions
- 5 Pressure distributions and lift on flat and cambered sections at small angles of attack
- 6 Design of hydrofoil sections
- 7 Real fluid effects and comparisons of theoretically and experimentally determined characteristics
- 8 Cavitation
- 9 Actuator disc theory
- 10 Wing theory
- 11 Lifting-line representation of propellers
- 12 Propeller design via computer and practical considerations
- 13 Hull-wake characteristics
- 14 Pressure fields generated by blade loading and thickness in uniform flows; comparisons with measurements
- 15 Pressure fields generated by blade loadings in hull wakes
- 16 Vibratory forces on simple surfaces
- 17 Unsteady forces on two-dimensional sections and hydrofoils of finite span in gusts
- 18 Lifting-surface theory
- 19 Correlations of theories with measurements
- 20 Outline of theory of intermittently cavitating propellers
- 21 Forces on simple bodies generated by intermittent cavitation
- 22 Pressures on hulls of arbitrary shape generated by blade loading, thickness and intermittent cavitation
- 23 Propulsor configurations for increased efficiency
- Appendices
- Mathematical compendium
- References
- Authors cited
- Sources of figures
- Index
18 - Lifting-surface theory
Published online by Cambridge University Press: 07 May 2010
- Frontmatter
- Contents
- Preface
- Notation
- Abbreviations
- 1 Brief review of basic hydrodynamic theory
- 2 Properties of distributions of singularities
- 3 Kinematic boundary conditions
- 4 Steady flows about thin, symmetrical sections in two dimensions
- 5 Pressure distributions and lift on flat and cambered sections at small angles of attack
- 6 Design of hydrofoil sections
- 7 Real fluid effects and comparisons of theoretically and experimentally determined characteristics
- 8 Cavitation
- 9 Actuator disc theory
- 10 Wing theory
- 11 Lifting-line representation of propellers
- 12 Propeller design via computer and practical considerations
- 13 Hull-wake characteristics
- 14 Pressure fields generated by blade loading and thickness in uniform flows; comparisons with measurements
- 15 Pressure fields generated by blade loadings in hull wakes
- 16 Vibratory forces on simple surfaces
- 17 Unsteady forces on two-dimensional sections and hydrofoils of finite span in gusts
- 18 Lifting-surface theory
- 19 Correlations of theories with measurements
- 20 Outline of theory of intermittently cavitating propellers
- 21 Forces on simple bodies generated by intermittent cavitation
- 22 Pressures on hulls of arbitrary shape generated by blade loading, thickness and intermittent cavitation
- 23 Propulsor configurations for increased efficiency
- Appendices
- Mathematical compendium
- References
- Authors cited
- Sources of figures
- Index
Summary
Ship propellers have wide blades to distribute the loading over the blades. As we have seen previously this is necessary to reduce local negative pressures to avoid, as much as possible, the generation of cavitation. We can then think of the blades as low-aspect-ratio wings that rotate and translate through the water. To describe the flow we consider the propeller blades as lifting surfaces over which we distribute singularities to model the effects of blade loading and thickness. This was done in Chapter 14 for uniform inflows and in Chapter 15 for varying blade loadings in hull wakes. But in those chapters we only considered the pressure from assumed distributions of loading and thickness over the propeller blades. To be able to find these distributions we must establish a relation between the pressure and the velocity and fulfill the kinematic boundary condition on the blades. We anticipate that the operation of the blades in the spatially varying flow, generated by the hull, will give rise to forces which vary with blade position. Hence it is necessary to treat the blades as lifting surfaces with non-stationary pressure distributions.
In this chapter an overview of the extensive literature of the past three decades is followed by a detailed development of a linear theory which is sufficiently accurate for prediction of the unsteady forces arising from only the temporal-mean spatial variations of inflow.
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- Hydrodynamics of Ship Propellers , pp. 334 - 373Publisher: Cambridge University PressPrint publication year: 1993