Unified Rotor Lifting Line Theory

2013 ◽  
Vol 57 (04) ◽  
pp. 181-201
Author(s):  
Brenden P. Epps ◽  
Richard W. Kimball
Keyword(s):  
Axial Flow ◽  
Preliminary Design ◽  
Propeller Design ◽  
Performance Curves ◽  
Line Theory ◽  
Parametric Studies ◽  
Lifting Line ◽  
Lifting Line Method ◽  
Lifting Line Theory ◽  
Line Analysis

A unified lifting line method for the design and analysis of axial flow propellers and turbines is presented. The method incorporates significant improvements to the classical lifting line methods for propeller design to extend the method to the design of turbines. In addition, lifting line analysis methods are developed to extend the usefulness of the lifting line model to allow generation of performance curves for off-design analysis. The result is a fast computational methodology for the design and analysis of propellers or turbines that can be used in preliminary design and parametric studies. Design and analysis validation cases are presented and compared with experimental data.

A New Approach to Lifting Line Theory: Hub and Duct Effects

2006 ◽  
Vol 50 (02) ◽  
pp. 138-146
Author(s):  
Victor G. Mishkevich
Keyword(s):  
Mathematical Model ◽  
Singular Integrals ◽  
Jacobi Polynomials ◽  
New Approach ◽  
Improve Design ◽  
Propeller Design ◽  
Line Theory ◽  
Circulation Distribution ◽  
Lifting Line ◽  
Lifting Line Theory

This paper deals with a new approach to lifting line theory in which the presence of a hub and/or duct is taken into account by introducing the generalized induction factors. The proposed mathematical model is built on the assumption that the hub and/or duct are simulated with infinite cylinders. The circulation distribution function is represented in the form of a series of orthogonal Jacobi polynomials that covers all cases that can occur in practical propeller design, including both zero and nonzero gap conditions. The integral equation of the lifting line theory is solved numerically by applying the highest accuracy quadrature formula for singular integrals. Propellers with optimum and arbitrary circulation distribution are considered. The proposed theory is intended to improve design of the near hub and duct blade sections, cavitation control, and integral propeller characteristics. Numerical results are presented for the purpose of comparison with different methods and to illustrate the developed approach.

A Method for Predicting Contra Rotating Propellers Off-Design Performance

2014 ◽  
Author(s):  
Matthieu Dubosc ◽  
Nicolas Tantot ◽  
Philippe Beaumier ◽  
Grégory Delattre
Keyword(s):  
Design Tool ◽  
Preliminary Design ◽  
Detailed Design ◽  
One Dimensional ◽  
Open Rotor ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Complex Methods ◽  
Engine Cycle

This article presents a method for predicting contra rotating propellers individual and total performance which is fast and robust enough to be used in performance engine cycle and engine subsystems detailed design. The method is based on the use of single propeller maps and models mutual induced velocities thanks to one-dimensional theories. These velocities are responsible for interferences between propellers. This article goes through the assumptions on which stands the proposed method and shows that it is relevant compared against more complex methods such as lifting line theory and definitively provides a valuable easy-to-enforce preliminary design tool for open rotor propulsor controls sizing.

Development of a Lifting-Line-Based Method for Preliminary Propeller Design

2018 ◽  
Author(s):  
Jose Rodolfo Chreim ◽  
Marcos de Mattos Pimenta ◽  
Joao Lucas Dozzi Dantas ◽  
Gustavo R. S. Assi ◽  
Eduardo Tadashi Katsuno
Keyword(s):  
Convergence Rates ◽  
Control Points ◽  
Numerical Implementation ◽  
Marine Propellers ◽  
Propeller Design ◽  
Line Theory ◽  
Thrust And Torque ◽  
Lifting Line ◽  
Lifting Line Theory

A novel formulation for marine propellers based on adaptations from wing lifting-line theory is presented; the method is capable of simulating propellers with skewed and raked blades. It also incorporates the influence of viscosity on thrust and torque from hydrofoil data through a nonlinear scheme that changes the location of the control points iteratively. Several convergence studies are conducted to verify the different aspects of the numerical implementation and the results indicate satisfactory convergence rates for Kaplan, KCA, and B-Troost propellers. It is expected that the method accurately describes thrust, torque, and efficiency under the moderately loaded propeller assumption.

On the Rotor Lifting Line Wake Model

2017 ◽  
Vol 33 (01) ◽  
pp. 31-45
Author(s):  
Brenden Epps
Keyword(s):  
Horizontal Axis ◽  
Preliminary Design ◽  
Trailing Vortices ◽  
Line Theory ◽  
Wake Model ◽  
Model Versus ◽  
Line Design ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Horizontal Axis Turbine

This article comments on the wake model used in moderately loaded rotor lifting line theory for the preliminary design of propellers and horizontal-axis turbines. Mathematical analysis of the classic wake model reveals an inconsistency between the induced velocities numerically computed by the model versus those theoretically predicted by the model. An improved wake model is presented, which better agrees with theory than previous models and thus improves the numerical consistency and robustness of rotor lifting line design algorithms. The present wake model analytically relates the pitch of the trailing vortices to the pitch of the total inflow computed at the lifting line control points. For conciseness, the article focuses on the propeller case, although both propeller and horizontal-axis turbine examples are presented.

An improved nonlinear lifting-line theory.

AIAA Journal ◽  
1973 ◽  
Vol 11 (5) ◽  
pp. 739-742 ◽  
Author(s):  
CHUAN-TAU LAN
Keyword(s):  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory

A comprehensive comparative investigation of the Lifting Line Theory and Blade Element Momentum Theory applied to small wind turbines

2021 ◽  
pp. 1-25
Author(s):  
K.A.R. Ismail ◽  
Willian Okita
Keyword(s):  
Wind Turbines ◽  
Power Coefficient ◽  
Computational Time ◽  
Local Flow ◽  
Small Wind Turbines ◽  
Wake Effects ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Blade Element

Abstract Small wind turbines are adequate for electricity generation in isolated areas to promote local expansion of commercial activities and social inclusion. Blade element momentum (BEM) method is usually used for performance prediction, but generally produces overestimated predictions since the wake effects are not precisely accounted for. Lifting line theory (LLT) can represent the blade and wake effects more precisely. In the present investigation the two methods are analyzed and their predictions of the aerodynamic performance of small wind turbines are compared. Conducted simulations showed a computational time of about 149.32 s for the Gottingen GO 398 based rotor simulated by the BEM and 1007.7 s for simulation by the LLT. The analysis of the power coefficient showed a maximum difference between the predictions of the two methods of about 4.4% in the case of Gottingen GO 398 airfoil based rotor and 6.3% for simulations of the Joukowski J 0021 airfoil. In the case of the annual energy production a difference of 2.35% is found between the predictions of the two methods. The effects of the blade geometrical variants such as twist angle and chord distributions increase the numerical deviations between the two methods due to the big number of iterations in the case of LLT. The cases analyzed showed deviations between 3.4% and 4.1%. As a whole, the results showed good performance of both methods; however the lifting line theory provides more precise results and more information on the local flow over the rotor blades.

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