Showing papers on "Blade element momentum theory published in 1997"
TL;DR: In this paper, the use of material in a 2.5 m long fibreglass composite wind turbine blade is discussed. And a program was written to create a detailed finite element mesh of the blade, using design data from blade element theory and panel code predictions, in a format suitable for direct input into a commercially available finite element software package.
102 citations
TL;DR: In this paper, a method for predicting the aerodynamic response of a vibrating blade row that is part of a multistage turbomachine is presented, where the coupling between blade rows is modeled using a subset of the so-called spinning modes, i.e., pressure, vorticity and entropy waves, which propagate between the blade rows.
Abstract: A computational method is presented for predicting the unsteady aerodynamic response of vibrating blade row that is part of a multistage turbomachine. Most current unsteady aerodynamic theories model a single blade row isolated in an infinitely long duct. This assumption neglects the potentially important influence of neighboring blade rows. The present coupled mode analysis is an elegant and computationally efficient method for modeling neighboring blade row effects. Using this approach, the coupling between blade rows is modeled using a subset of the so-called spinning modes, i.e., pressure, vorticity, and entropy waves, which propagate between the blade rows. The blade rows themselves are represented by reflection and transmission coefficients. These coefficients describe how spinning modes interact with, and are scattered by, a given blade row. The coefficients can be calculated using any standard isolated blade row model; here we use a linearized full potential flow model together with rapid distortion theory to account for incident vortical gusts. The isolated blade row reflection and transmission coefficients, interrow coupling relationships, and appropriate boundary conditions are all assembled into a small sparse linear system of equations that describes the unsteady multistage flow. A number of numerical examples are presented to validate the method and to demonstrate the profound influence of neighboring blade rows on the aerodynamic damping of cascade of vibrating airfoils.
49 citations
TL;DR: In this article, a 3D Navier-Stokes code with film injection and the measured heat flux on a fully film-cooled rotating transonic turbine blade was compared to the Nusselt number data obtained on a rotating turbine blade.
33 citations
01 Jun 1997
TL;DR: In this paper, a two-dimensional viscous inverse method for the design of turbine and compressor blades is presented, which iteratively modifies an initial geometry until a prescribed pressure distribution is reached on the blade surface.
Abstract: A two-dimensional viscous inverse method for the design of compressor and turbine blades is presented. It iteratively modifies an initial geometry until a prescribed pressure distribution is reached on the blade surface.The method solves the time-dependent Navier—Stokes equations in a numerical domain of which some boundaries (the blade walls) move during the transient part of the computation. The geometry modification algorithm is based on the transpiration principle: a normal velocity distribution is computed from the difference between the actual and prescribed pressure distributions, and is used to modify the blade shape. A time iteration is then performed on this new blade shape, taking into account the grid movement during the time stepping.A two-dimensional upwind finite-volume Navier—Stokes solver has been developed. The multiblock strategy allows for a selective concentration of the discretization points in the zones of higher gradients. Applications to turbine and compressor blade design...
29 citations
02 Jun 1997
TL;DR: In this paper, a 3D inverse method was used to modify the Rotor 67 geometry to produce a prescribed pressure loading distribution, with the blade tangential thickness distribution and the blade stacking line at midchord kept the same as the original Rotor67 design.
Abstract: A design modification of Rotor 67 is carried out with a full 3D inverse method. The blade camber surface is modified to produce a prescribed pressure loading distribution, with the blade tangential thickness distribution and the blade stacking line at midchord kept the same as the original Rotor 67 design. Because of the inviscid-flow assumption used in the current version of the method, Rotor 67 geometry is modified for use at a design point different from the original design value. In the subsonic section, smooth pressure loading shapes generally produce blades with well-behaved blade surface pressure distributions. In the supersonic section, this study shows that the strength and position of the passage shock correlate with the characteristics of the blade pressure loading shape. In general, “smooth” prescribed blade pressure loading distributions generate blade designs with reverse cambers which have the effect of weakening the passage shock.Copyright © 1997 by ASME
9 citations
TL;DR: In this paper, the authors presented a procedure to extend a recently developed three-dimensional inverse method for infinitely thin blades to handle blades with finite thickness, where the prescribed quantities are the blade pressure loading and the blade thickness distributions, and the calculated quantity is the blade mean camber line.
Abstract: This paper presents a procedure to extend a recently developed three-dimensional inverse method for infinitely thin blades to handle blades with finite thickness. In this inverse method, the prescribed quantities are the blade pressure loading and the blade thickness distributions, and the calculated quantity is the blade mean camber line. The method is formulated in the fully inverse mode whereby the blade shape is determined iteratively using the flow-tangency condition along the blade surfaces. Design calculations are presented for an inlet guide vane, an impulse turbine blade, and a compressor blade in the two-dimensional inviscid- and incompressible-flow limit. Consistency checks are carried out for these design calculations using a panel analysis method and the analytical solution for the Gostelow profile.
9 citations
01 Jan 1997
TL;DR: An optimization procedure is developed for addressing the design of composite tilt rotor blades using a higher-order laminate theory which approximates the elasticity solution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters.
Abstract: An optimization procedure is developed for addressing the design of composite tilt rotor blades. A comprehensive technique, based on a higher-order laminate theory, is developed for the analysis of the thick composite load-carrying sections, modeled as box beams, in the blade. The theory, which is based on a refined displacement field, is a three-dimensional model which approximates the elasticity solution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both inplane and out-of-plane warping are included automatically in the formulation. The model can accurately capture the transverse shear stresses through the thickness of each wall while satisfying stress free boundary conditions on the inner and outer surfaces of the beam. The aerodynamic loads on the blade are calculated using the classical blade element momentum theory. Analytical expressions for the lift and drag are obtained based on the blade planform with corrections for the high lift capability of rotor blades. The aerodynamic analysis is coupled with the structural model to formulate the complete coupled equations of motion for aeroelastic analyses. Finally, a multidisciplinary optimization procedure is developed to improve the aerodynamic, structural and aeroelastic performance of the tilt rotor aircraft. The objective functions include the figure of merit in hover and the high speed cruise propulsive efficiency. Structural, aerodynamic and aeroelastic stability criteria are imposed as constraints on the problem. The Kreisselmeier-Steinhauser function is used to formulate the multiobjective function problem. The search direction is determined by the Broyden-Fletcher-Goldfarb-Shanno algorithm. The optimum results are compared with the baseline values and show significant improvements in the overall performance of the tilt rotor blade.
4 citations
30 Sep 1997
TL;DR: In this article, a numerical modeling of turbulence effects of a flow around a rotor blade was presented, which was extended to demonstrate unsteady calculations due to blade oscillations. But the simulation of the flows in the above mentioned regions to determine mean velocity components, the turbulence energy levels, pressures, and thermodynamic properties such as temperatures and densities.
Abstract: Unsteady load predictions on steam turbine blades are needed for a better understanding of high cycle fatigue blade failures. The forced response due to rotor-stator interaction and the unsteady loads due to blade oscillatory motion are major factors for the cause of stresses. In addition, turbulence, which is generated through the stator nozzle passages of a turbine, significantly affects the flow characteristics and heat transfer of the rotor blades.This paper presents a numerical modeling of turbulence effects of a flow around a rotor blade which was extended to demonstrate unsteady calculations due to blade oscillations. The grids were generated by employing the boundary-fitted algebraic grid generation technique. In the computations, the unsteady compressible Navier-Stokes equations were solved for the simulation of the flows in the above mentioned regions to determine mean velocity components, the turbulence energy levels, pressures, and thermodynamic properties such as temperatures and densities. The computed pressure distributions along a blade were compared with the published experimental data and the code was validated by showing reasonable agreement with the results. Some numerical examples are presented by using different turbulence models to investigate the nature of the turbulence occurring in the flow around a blade. Furthermore, the computational model was tested for its applicability to blade flutter in three vibrational modes — tangential, axial, and twist modes.Copyright © 1997 by ASME
1 citations
02 Jun 1997
TL;DR: In this paper, a two-dimensional viscous inverse method for the design of turbine and compressor blades is presented, where an initial geometry is modified iteratively to reach a target pressure distribution imposed on the blade surfaces.
Abstract: A two-dimensional viscous inverse method for the design of compressor and turbine blades is presented. An initial geometry is modified iteratively to reach a target pressure distribution imposed on the blade surfaces. The Navier-Stokes equations are solved in a numerical domain of which some boundaries (the blade walls) move during the transient part of the computation. The blade modifications are based on the transpiration principle. The transpiration flux is computed from the difference between the actual and the prescribed pressure distributions.A high-resolution Navier-Stokes solver has been developed for this purpose, based on a Finite-Volume formulation. Multi-block structured grids allow for a selective concentration of discretization points in the zones of higher gradients. Both explicit (Runge-Kutta) and implicit (Newton-Krylov) time integration schemes have been implemented.Applications to turbine and compressor blade design illustrate the accuracy of the flow computation, and the efficiency of the inverse method.Copyright © 1997 by ASME
1 citations
07 Apr 1997
TL;DR: In this article, the aeroelastic stability of helicopter rotors in hover is examined through a generalized dynamic inflow model coupled to elastic restraint rigid blade equations, where the blade configuration contains a root spring to model pitch-link flexibility and a set of hub and blade torsional springs to restrain flap and lead-lag motions.
Abstract: The aeroelastic stability of helicopter rotors in hover is examined through a generalized dynamic inflow model coupled to elastic restraint rigid blade equations. The blade configuration contains a root spring to model pitch-link flexibility, and a set of hub and blade torsional springs to restrain flap and lead-lag motions. The state-space treatment of the inflow allows a standard eigenanalysis for the time dependent equations established after perturbations are taken about blade equilibrium and steadystate inflow. Static and dynamic analysis results for a two-bladed rotor show how the finite-state unsteady aerodynamics performs in the presence of a simple rigid blade model. Steady-state results capture three-dimensional tip relief effects and show good agreement with their elastic blade counterparts. Damping results for configurations including precone and droop fail to correlate well because the structural model does not account for elastic flap-lagtorsion couplings.