Experimental research has been completed using a custom designed and built 4m diameter wind turbine in a university operated wind facility. The primary goals of turbine testing were to determine the power production of the turbine and to apply the particle image velocimetry (PIV) technique to produce flow visualization images and velocity vector maps near the tip of a blade. These tests were completed over a wide range of wind speeds and turbine blade rotational speeds. This testing was also designed to be a preliminary study of the potential for future research using the turbine apparatus and to outline it's limitations. The goals and results of other large scale turbine tests are also briefly discussed with a comparison outlining the unique aspects of the experiment outlined in this thesis. Power production tests were completed covering a range of mean wind speeds, 6.4 m/s to 11.1 m/s nominal, and rotational rates, 40 rpm to 220 rpm. This testing allowed the total power produced by the blades to be determined as a function of input wind speed, as traditionally found in power curves for commercial turbines. The coefficient of power, Cp, was determined as a function of the tip speed ratio which gave insight into the peak power production of the experimental turbine. It was found, as expected, that the largest power production occurred at the highest input wind speed, 11.1 m/s, and reached a mean value of 3080 W at a rotational rate of 220 rpm. Peak Cp was also found, as a function of the tip speed ratio, to approach 0.4 at the maximum measurable tip speed ratio of 8. Blade element momentum (BEM) theory was also implemented as an aerodynamic power and force prediction tool for the given turbine apparatus. Comparisons between the predictions and experimental results were made with a focus on the Cp power curve to verify the accuracy of the initial model. Although the initial predictions, based on lift and drag curves found in Abbot and Von Doenhoff (1959), were similar to experimental results at high tip speed ratios an extrapolation of the data given by Hoffman et al. (1996) was found to more closely match the experimental results over the full range of tip speed ratios. Finally PIV was used to produce flow visualization images and corresponding velocity maps of the chord-wise air flow over an area at a radius ratio of 0.9, near the tip of a blade. This technique provided insight into the flow over a blade at three different tip speed ratios, 4, 6 and 8, over a range of wind speeds and rotational rates. A discussion of the unique aspects and challenges encountered using the PIV technique is presented including: measuring an unbounded external flow on a rotating object and the turbulence in the free stream affecting the uniform seeding and stability of the flow.

Renewable energy is a serious alternative to deliver the energy needs of an increasing world population and improve economic activity. Wind energy provides better environmental and economic benefits in comparison with the other renewable energy sources. Wind energy is capable of providing 72 TW (TW = 10^12 W) of electric power, which is approximately four and half times the world energy consumption of 15.8 TW as reported in 2006. Since power output extracted from wind turbines is proportional to the square of the blade length and the cube of the wind speed, wind turbine size has grown rapidly in the last two decades to match the increase in power output. As the blade length increases, so does its weight opening up design possibilities to introduce hybrid glass and carbon fiber composite materials as lightweight structural load bearing alternatives. Herein, we investigate the feasibility of introducing modular composite tubulars as well as hybrid sandwich composite skins in the next generation blades. After selecting a target energy output, 8 MW with 80 m blade, airfoil geometry and the layup for the skin as well as internal reinforcements are proposed. They are incorporated into the computational blade via linear shell elements for the skin, and linear beam elements for the composite tubulars to assess the relationship between weight reduction and structural performance. Computational simulations are undertaken to understand the static and dynamic regimes; specifically, displacements, stresses, and vibration modes. The results showed that the composite layers did not exhibit any damage. However, in the balsa core of the sandwich skin, the von Mises stress exceeded its allowable at wind speeds ranging from 11.0 m/sec to 12.6 m/sec. In the blades with composite tubular reinforcement, two different types of damage are observed: a. Stress concentrations at the tubular-skin attachments, and b. Highest von Mises stress caused by the flapping bending moment. The vibration studies revealed a strong coupling mode, bending and twist, at the higher natural frequencies of the blade with tubular truss configuration. The weight saving measures in developing lighter blades in this study did not detract from the blades structural response for the selected load cases.

Abstract Maintenance makes machine life long more and gets no loss about a chain reaction on part broken. Repair a part that has high complex and is important. It need engineer experience to decide its maintenance process plan. For turbine blade maintenance style that has various type and a small quantity. Different broken feature have different maintenance process in the maintenance process planning stage. This thesis creates a system for this property maintenance on the process planning system on the Maintenance of turbine blades. Analyzing blade broken feature and classifying the feature to bring up a case-based reasoning and fuzzy set operation that usually see in expert systems. It uses case-based databases to save engineer experiences and analysis to decide critical maintenance process factors. The critical factors can help find out similarity case and modulate a newer case. It needs to create a proto-type system for these purposes. The first, classifying turbine blades broken feature and coding the repair process for different maintenances. The second, using fuzzy set language to determine case¡¦s similarity and finding out algorithm. Integrating product data management system and the system. The research uses a company as case study to test and verify the proto-type system.

Computations were run to study heat transfer coefficient augmentation with film cooling for a simulated gas turbine blade leading edge. The realizable k-[epsilon] turbulence model (RKE) and Shear Stress Transport k-[omega] turbulence model (SST) were used for the computational simulations. RKE computations completed at a unity density ratio were confirmed to be consistent with experimental measurements conducted by Yuki et al.(1998) and Johnston et al. (1999) whereas SST computations exhibited significant discrepancies. Moreover the effect of the density ratio on heat transfer coefficient augmentation was studied because experimental measurements of heat transfer coefficient augmentation with film cooling are generally constrained to unity density ratio tests. It was shown that heat transfer coefficient augmentation can be simulated using unity density ratio jets, but only when scaled with the momentum flux ratio of the coolant jets. / text

An accelerated high cycle fatigue testing approach is presented to determine the fatigue endurance limit of materials at high frequencies. Base excitation of a tapered plaque driven into a high frequency resonance mode allows the test to be completed in a significantly shorter time. This high cycle fatigue testing is performed using the tracked sine resonance search and dwell strategy. The controller monitors the structural health during the test. Any change in the dynamic response indicates crack initiation in the material. In addition, a shape optimization finite element model is conducted for the design of the tapered plaques. An integrated neural (Neural-Network) genetic (NSGA_II) optimization technique is implemented to carry out the shape optimization for this component. This process results in a significant reduction in the computational cost. A Pareto set is then produced that meets the designer’s requirements and provides the decision maker several alternatives to choose from.

An accelerated high cycle fatigue testing approach is presented to determine the fatigue endurance limit of materials at high frequencies. Base excitation of a tapered plaque driven into a high frequency resonance mode allows the test to be completed in a significantly shorter time. This high cycle fatigue testing is performed using the tracked sine resonance search and dwell strategy. The controller monitors the structural health during the test. Any change in the dynamic response indicates crack initiation in the material. In addition, a shape optimization finite element model is conducted for the design of the tapered plaques. An integrated neural (Neural-Network) genetic (NSGA_II) optimization technique is implemented to carry out the shape optimization for this component. This process results in a significant reduction in the computational cost. A Pareto set is then produced that meets the designer’s requirements and provides the decision maker several alternatives to choose from.

The effect of rotation on flow in a gas turbine blade cooling duct model is investigated experimentally. The present work consists of velocity measurements at different locations in a test section with a 180° bend with ribs on one wall. Three geometric rib parameters are considered; rib-rib spacing, rib orientation angle and rib blockage ratio. PIV is used for flow visualization and analysis. Along with the clean duct measurements, ribs with blockage ratios, b/h, of 0.25 and 0.125 were considered. The b/h = 0.25 cases have been comprehensively analyzed while the b/h = 0.125 cases have been studied at the post-bend region of the duct only. Reynolds number considered is in the range of approximately 5000-40,000 and the rotation speed is varied for a rotation number from 0 to 7. It is observed that rotation has a significant effect on secondary flows within the rotating duct. For blockage ratio, b/h = 0.25, at a constant Re and Ro, the RMS of fluctuations of velocity do not show large spatial variations with ribs or rib orientations. At higher Re, the value decreases in comparison to the low Re cases. The kinetic energy of fluctuations increases due to the presence of ribs, indicating better heat transfer for the ribbed duct, but do not show large variations with rib orientation angle. The fluctuations and kinetic energy show maximum values at the post-bend regions of the duct. The velocity fields and PDFs show a possible cause for e°cient heat transfer for the 45° rib arrangement as compared with the 90° rib cases. At high Ro, the absolute value of circulation has a large increase at the post-bend and thereafter there is a gradual decay at the exit for all cases. The ribs with blockage ratio of b/h = 0.125 showed no marked changes in circulation with changes in rib orientation angle, thus implying that the rib blockage plays a role in the generation of secondary flows, particularly in conjunction with rotation.

A model of a gas turbine blade cooling channel equipped with turbulators and a backward facing step geometry was examined. Up to four turbulators oriented cross-stream and inclined 45° to the flow direction were mounted in the channel. The blockage ratio b/H of the turbulators and the height h/H of the backward facing step was 0:125 and 0:14 respectively. The number of turbulators as well as their size was varied. In a preliminary investigation, hot-wire and pressure measurements were taken for three different Reynolds numbers (5,000, 12,000, 18,000)in the center plane of the test section. Subsequently, particle image velocimetry (PIV) measurements were made on the same geometries. Results of PIV measurements for a Reynolds number range of Reb=600 to 5,000 for the turbulators and Reh=1,500 to 16,200 for the backward facing step are presented, where Reynolds numbers are based on turbulator height b and step height h, respectively. Plots of the velocity field, vorticity, reverse flow probability and RMS velocity are shown. The focus is on the steady flow behavior but also the unsteadiness of the flow is discussed in one section. Also reattachment lengths were obtained and compared among the various turbulator arrangements and the backward facing step geometry. It was found that the flow becomes periodic after three or four ribs. For one turbulator, a very large separation region was observed. The magnitude of the skin friction factor was found to be the highest for two ribs. If the first rib is replaced by a smaller rib, the skin friction factor becomes the lowest for this case. Compared to the backward facing step, the flow reattaches earlier for multiple turbulators. A dependency of reattachment length on Reynolds number was not observed.

The flow field around a low pressure turbine blade is examined using smoke-wire flow visualization, static surface pressure measurements, and particle image velocimetry (PIV). The purpose of the experimental study is to investigate the transition and separation characteristics on low pressure turbine blades under low Reynolds number (Re) and varying freestream turbulence intensity (FSTI). A cascade model consisting of 6 Pratt andamp; Whitney PAK-B low pressure turbine blades was examined in a wind tunnel using PIV and flow visualization. Smoke-wire visualization was performed for test section exit angles of 93°, 95°, and 97°, in the range Re = 3 · 104 to 9 · 104 and three levels of FSTI varied with a passive grid. The locations of separation and transition were determined to be approximately 45% and 77% of the suction surface length, respectively, based upon the smoke stream lines observed in the images, and appear to be independent of Re, turning angle, and FSTI. The maximum size of the separation bubble was found to decrease with increasing Re, turning angle, and FSTI. PIV images from three camera views were processed for an exit angle of 95° and a Re range of 3:0 · 104 to 30:0 · 104 and three levels of FSTI. Velocity, vorticity, and reversed flow probability field plots were generated along with velocity, vorticity, and RMS velocity profiles. The point of separation point was determined to be from 63% SSL to 67% SSL. The area of reversed flow was computed for each image pair from camera views 1 and 3, as an approxiamtion of the relative size of the separation region. For low Re and FSTI cases the area was much larger than for higher FSTI cases at any Re. The raw PIV images include some of the rst clear pictures of the turbulent flow structures forming in the unsteady shear layer over the suction surface of low pressure turbine blades. Several movies are compiled that show how the geometry and location of the shear layer evolve in time for a given set of flow conditions.

This study investigates the manifestation of geometric features of turbine blades in signatures of non-optical time of arrival (ToA) probes. The approach enables an evaluation of the various signal characteristics used for defining ToA for a range of airfoil geometries and provides knowledge about additional waveform characteristics. The objective of this research is to increase the accuracy of microwave ToA probes by gaining a better understanding of the microwave signals in five steps. Firstly, ToA definitions used in the past are compared. Considering accuracy, computational effort, and versatility, the constant fraction crossing definition is found to be the most accurate. Secondly, an experimental apparatus capable of measuring airfoil ToA with microwave probes and optical probes as a reference is designed and built. As a third step, a catalog of 16 turbine blade geometries is developed. Fourthly, the signatures of these turbine blades are acquired using both the optical and the microwave probes. Finally, the impact of the geometric effects on the signatures is evaluated. The quality of the microwave results is found to be highly dependent on the polarization of the microwaves. Analysis of the time domain signal shows that decreasing the blade width, increasing the chord angle, or incorporating a blade tip pocket or a varying cross-section leads to a decrease in the amplitude of the peak caused by the blade. Increasing the blade width and incorporating a chord angle leads to an increase in peak width. A frequency domain analysis is conducted on the microwave signals and verified using a synthetic signal. This analysis confirms the findings from the time domain analysis. The time domain analysis of the laser measurements shows that the spatial resolution of the laser is much higher than that of the microwave sensor. Consequently, the signal acquired with the optical setup provides a good means of defining the blade ToA. The knowledge gained in this study about the sensor and its interaction with passing blade tips of varying geometry can be used to enhance the understanding of microwave ToA measurements. This knowledge provides further insight into airfoil and engine health.