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Analytical investigation of effect of water-cooled turbine blades on performance of turbine-propeller power plants

Description: From Introduction: "Finally the work of the report is applied exclusively to consideration of the turbine-propeller power plant because previous performance analyses of the various gas-turbine propulsion systems combine with recent improvements in propeller design indicate that it is this combination which, will give the best over-all performance in the speed ranges considered."
Date: August 16, 1948
Creator: Bowman, William D
Partner: UNT Libraries Government Documents Department

Determination and use of the local recovery factor for calculating the effectiveness gas temperature for turbine blades

Description: In an in experimental investigation of local recovery factors for a blade having a pressure distribution similar to that of a typical reaction-type turbine blade, it a was found that the recovery factors were essentially independent of Mach number, Reynolds number, pressure gradient, and position on the blade surface except for regions where the boundary layer was probably in the transition range from laminar to turbulent. The recommended value of local subsonic recovery factor for use in calculating the effective gas temperature for gas turbine blades was 0.89.
Date: September 24, 1951
Creator: Esgar, Jack B. & Lea, Alfred L.
Partner: UNT Libraries Government Documents Department

Application of supersonic vortex-flow theory to the design of supersonic impulse compressor- or turbine-blade sections

Description: From Introduction: "The purpose of this paper is to present an analytical method for the design of two-dimensional related selection of a blade for particular rotor conditions may be made quickly and easily and its performance deduced from tests of representative sections in cascade."
Date: April 24, 1952
Creator: Wlodarski, John; Sterrett, James R & Boxer, Emanuel
Partner: UNT Libraries Government Documents Department

An analytical method for evaluating factors affecting application of transpiration cooling to gas turbine blades

Description: From Introduction: "A survey of some of the advantages and problems associated with transpiration cooling of gas-turbine engines is given in reference 1, and its is shown therein that high pressure gradients around the periphery of gas-turbine blades require that the blade wall permeability be varied around the blade periphery in order for uniform cooling to be obtained over the entire blade surface. This fact is verified in experimental investigations of transpiration-cooled turbine blades mounted in a static cascade (references 2 and 3) where it is shown that although transpiration cooling results in extremely effective cooling in the midchord region of the blade, there are very large variations in the chordwise temperature distribution because of improper permeability variation."
Date: September 8, 1952
Creator: Esgar, Jack B
Partner: UNT Libraries Government Documents Department

Analytical investigation of distribution of centrifugal stresses and their relation to limiting operating temperatures in gas-turbine blades

Description: From Introduction: "Analyses that provide a basis for comparing the centrifugal-stress distributions inherent in jet-engine turbine blades of several designs currently in use were therefore made and are presented."
Date: April 12, 1948
Creator: Kemp, Richard H & Morgan, William C
Partner: UNT Libraries Government Documents Department

Analytical determination of local surface heat-transfer coefficients for cooled turbine blades from measured metal temperatures

Description: From Summary: "Procedures for applying these analytical methods to experimentally measured blade-metal temperatures are presented. Data are presented for the leading and trailing edge of a symmetrical water-cooled blade to illustrate the validity of the methods for those portions of the blade. In addition to the application to turbine blades, the methods can be applied to any heat-transfer apparatus having a profile that can be approximated by the shape discussed."
Date: April 10, 1950
Creator: Brown, W. B. & Esgar, J. B.
Partner: UNT Libraries Government Documents Department

Tabulation of mass-flow parameters for use in design of turbomachine blade rows for ratios of specific heats of 1.3 and 1.4

Description: Report presenting mass-flow tables for ratios of specific heats for the entire range of critical velocity ratio. The tables enable a quick and accurate determination of the integrated average specific mass flow across a region where the end-point velocities are known. A numerical example using the tables is also provided.
Date: October 1956
Creator: Whitney, Warren J.
Partner: UNT Libraries Government Documents Department

Investigation of effects of grain size upon engine life of cast AMS 5385 gas turbine blades

Description: Report presenting an investigation to determine the effects of pouring temperature and grain size on the uniformity of lives and initial failure times of groups of AMS 5385 gas turbine blades and to relate the individual lives of the blades to grain size. This is due to the fact that the uniformity of lift of cast alloy gas-turbine blades is generally unsatisfactory. Results regarding the metallurgical examination are provided.
Date: July 6, 1953
Creator: Hoffman, C. A. & Gyorgak, C. A.
Partner: UNT Libraries Government Documents Department

Performance of Inconel 550 turbine blades in a turbojet engine and effects of different forging temperatures and heat treatments

Description: Report presenting an investigation to determine the effects of forging at 1950 degrees and 2150 degrees Fahrenheit as well as the effects of several heat treatments on the performance of Inconel 550 in a turbojet engine. Differences in engine performance of the different turbine blades could not be associated with consistent differences in microstructure or grain size. Results regarding blade performance, blade elongation during engine operation, microstructure of as-heat-treated blades, grain size, metallurgical studies of failed blades, stress-rupture tests, and hardness are provided.
Date: August 16, 1955
Creator: Gyorgak, C. A.; Johnston, J. R. & Weeton, J. W.
Partner: UNT Libraries Government Documents Department

Active load control techniques for wind turbines.

Description: This report provides an overview on the current state of wind turbine control and introduces a number of active techniques that could be potentially used for control of wind turbine blades. The focus is on research regarding active flow control (AFC) as it applies to wind turbine performance and loads. The techniques and concepts described here are often described as 'smart structures' or 'smart rotor control'. This field is rapidly growing and there are numerous concepts currently being investigated around the world; some concepts already are focused on the wind energy industry and others are intended for use in other fields, but have the potential for wind turbine control. An AFC system can be broken into three categories: controls and sensors, actuators and devices, and the flow phenomena. This report focuses on the research involved with the actuators and devices and the generated flow phenomena caused by each device.
Date: July 1, 2008
Creator: van Dam, C.P. (University of California, Davis, CA); Berg, Dale E. & Johnson, Scott J. (University of California, Davis, CA)
Partner: UNT Libraries Government Documents Department

Final Technical Report

Description: This variable length wind turbine blade project met the project objectives by successfully completing the task schedule. A set of variable length blades (8 to 12 meters in length) is now flying, in a configuration that is representative of a commercial blade designed to replace a standard 9 meter blade. Static testing and operations show that the blades are durable and stiff enough to prevent tower strikes. Power curve testing shows significant gains in low wind speed power production. An improved controller and drive mechanism have now been working for six months. Moving forward, we continue to monitor power curve, controller performance, and durability data. The project has made good progress towards understanding the costs and challenges associated with commercial production of variable length blades. Items that will require further study are: tip airfoil; blade pitching, tip and root interface design; jigs for more efficient construction, and optimization of subsystems
Date: June 30, 2005
Creator: Dawson, Mark H.
Partner: UNT Libraries Government Documents Department

Non-Destructive Evaluation of Wind Turbine Blades Using an Infrared Camera

Description: The use of a digital infrared as a non-destructive evaluation thermography camera (NDE) tool was ex- plored in two separate wind turbine blade fatigue tests. The fwst test was a fatigue test of part of a 13.1 meter wood-epoxy-composite blade. The second test was on a 4.25 meter pultruded fiber glass blade section driven at several mechanical resonant frequencies. The digital infrared camera can produce images of either the static temperature distribution on the surface of the specimen, or the dynamic temperature distribution that is in phase with a specific frequency on a vibrating specimen. The dynamic temperature distribution (due to thermoplastic effects) gives a measure of the sum of the principal stresses at each point on the surface. In the wood- epoxy-composite blade fatigue test, the point of ultimate failure was detected long before failure occurred. The mode shapes obtained with the digital infrared camera, from the resonant blade tests, were in very good agree- ment with the finite-element calculations. In addition, the static temperature images of the resonating blade showed two areas that contained cracks. Close-up dy- namic inf%red images of these areas showed the crack structure that agreed with subsequent dye-penetrant analysis.
Date: December 17, 1998
Creator: Beattie, A.G. & Rumsey, M.
Partner: UNT Libraries Government Documents Department

The Effect of Peel Stress on the Strength of Adhesively Bonded Joints

Description: Composite wind turbine blades are often attached to a metallic structure with an adhesive bond. The objective of this investigation is to determine which parameters affect the durability of these adhesively bonded joints. The composite-to-steel joint considered in this study typically fails when the adhesive debonds from the steel adherend. Previously, this joint was monotonically loaded in either compression or tension. Compressive and tensile axial loads of the same magnitude produce adhesive stresses with very similar magnitudes but opposite signs. (For the joint considered, tensile loads produce compressive peeh stresses in the adhesive at the location where debonding initiates.) The tensile specimens failed at much higher loads, establishing that the sign of the adhesive peel stresses strongly influences the single-cycle strength of these joints. Building on this earlier work, this study demonstrates that the adhesive peel stresses are also critical for fatigue loading. The results of low-cycle (axial) and high- cycle (bending) fatigue tests are presented. To complement the test results, finite element analyses demonstrate the localized nature of the peel stresses that develop in the adhesive. In addition, these analyses are used to investigate some of the causes of these peel stresses.
Date: October 14, 1998
Creator: Guess, T.R. & Metzinger, K.E.
Partner: UNT Libraries Government Documents Department

Design studies for twist-coupled wind turbine blades.

Description: This study presents results obtained for four hybrid designs of the Northern Power Systems (NPS) 9.2-meter prototype version of the ERS-100 wind turbine rotor blade. The ERS-100 wind turbine rotor blade was designed and developed by TPI composites. The baseline design uses e-glass unidirectional fibers in combination with {+-}45-degree and random mat layers for the skin and spar cap. This project involves developing structural finite element models of the baseline design and carbon hybrid designs with and without twist-bend coupling. All designs were evaluated for a unit load condition and two extreme wind conditions. The unit load condition was used to evaluate the static deflection, twist and twist-coupling parameter. Maximum deflections and strains were determined for the extreme wind conditions. Linear and nonlinear buckling loads were determined for a tip load condition. The results indicate that carbon fibers can be used to produce twist-coupled designs with comparable deflections, strains and buckling loads to the e-glass baseline.
Date: June 1, 2004
Creator: Valencia, Ulyses (Wichita State University, Wichita, KS) & Locke, James (Wichita State University, Wichita, KS)
Partner: UNT Libraries Government Documents Department

A simple method of estimating wind turbine blade fatigue at potential wind turbine sites

Description: This paper presents a technique of estimating blade fatigue damage at potential wind turbine sites. The cornerstone of this technique is a simple model for the blade`s root flap bending moment. The model requires as input a simple set of wind measurements which may be obtained as part of a routine site characterization study. By using the model to simulate a time series of the root flap bending moment, fatigue damage rates may be estimated. The technique is evaluated by comparing these estimates with damage estimates derived from actual bending moment data; the agreement between the two is quite good. The simple connection between wind measurements and fatigue provided by the model now allows one to readily discriminate between damaging and more benign wind environments.
Date: June 1, 1995
Creator: Barnard, J.C. & Wendell, L.L.
Partner: UNT Libraries Government Documents Department

Turbomachinery blade optimization using the Navier-Stokes equations

Description: A method is presented to perform aerodynamic design optimization of turbomachinery blades. The method couples a Navier-Stokes flow solver with a grid generator and numerical optimization algorithm to seek improved designs for transonic turbine blades. A fast and efficient multigrid, finite-volume flow solver provides accurate performance evaluations of potential designs. Design variables consist of smooth perturbations to the blade surface. A unique elliptic-hyperbolic grid generation method is used to regenerate a Navier-Stokes grid after perturbations have been added to the geometry. Designs are sought which improve a design objective while remaining within specified constraints. The method is demonstrated with two transonic turbine blades with different types and numbers of design variables.
Date: December 1, 1997
Creator: Chand, K. K. & Lee, K. D.
Partner: UNT Libraries Government Documents Department

Development of a more fish tolerant turbine runner advanced hydropower turbine project. Final report

Description: The Hidrostal pump is a single bladed combined screw/centrifugal pump which has been proven to transport fish with minimal injury. The focus of the ARL/NREC research project was to develop a new runner geometry which is effective in downstream fish passage and hydroelectric power generation. A flow of 1,000 cfs and a head in the range of 75 ft to 100 ft were selected for conceptual design of the new runner. Criteria relative to hydraulic characteristics which are favorable for fish passage were prepared based on a reassessment of the available information. Important criteria used to develop the new runner design included low pressure change rates, minimum absolute pressures, and minimum shear. Other criteria which are reflected in the runner design are a minimum number of blades (only two), minimum total length of leading edges, and large flow passages. Flow characteristics of the new runner were analyzed using two- dimensional and three-dimensional Computational Fluid Dynamic (CFD) models. The basic runner geometry was initially selected using the two-dimensional model. The three-dimensional model was used to investigate the flow characteristics in detail through the entire runner and to refine the design by eliminating potential problem areas at the leading and trailing edges. Results of the analyses indicated that the runner has characteristics which should provide safe fish passage with an overall power efficiency of approximately 90%. The size of the new runner, which is larger than conventional turbine runners with the same design flow and head, will provide engineering, fabrication, and installation.challenges related to the turbine components and the civil works. A small reduction in the overall efficiency would reduce the size of the runner considerably, would simplify the turbine manufacturing operations, and would allow installation of the new turbine at more hydroelectric sites.
Date: January 1, 1997
Creator: Cook, T.C.; Hecker, G.E.; Faulkner, H.B. & Jansen, W.
Partner: UNT Libraries Government Documents Department

Mechanical properties of Hysol EA-9394 structural adhesive

Description: Dextor`s Hysol EA-9394 is a room temperature curable paste adhesive representative of the adhesives used in wind turbine blade joints. A mechanical testing program has been performed to characterize this adhesive. Tension, compression stress relaxation, flexural, butt tensile, and fracture toughness test results are reported.
Date: February 1, 1995
Creator: Guess, T.R.; Reedy, E.D. & Stavig, M.E.
Partner: UNT Libraries Government Documents Department