Search results

This study aims to simulate Hunter turbine in Computer Forensic Examiner (CFX) environment dynamically. For this purpose, the turbine is designed in desired dimensions and simulated in ANSYS software under a specific fluid flow rate. The obtained values were then compared with previous studies for different values of angles (θ and α). The amount of validation error were obtained.

In this research, at first, the study of fluid flow and then the examination of that in the tidal turbine and identifying the turbines used for tidal energy extraction are performed. For this purpose, the equations governing flow and turbine are thoroughly investigated, and the computational fluid dynamic simulation is done after numerical modeling of Hunter turbine in a CFX environment.

The failure results showed; 11.25% for the blades to fully open, 2.5% for blades to start, and 2.2% for blades to close completely. Also, results obtained from three flow coefficients, 0.36, 0.44 and 0.46, are validated by experimental data that were in high-grade agreement, and the failure value coefficients of (0.44 and 0.46) equal (0.013 and 0.014), respectively.

In this research, at first, the geometry of the Hunter turbine is discussed. Then, the model of the turbine is designed with SolidWorks software. An essential feature of SolidWorks software, which was sorely needed in this project, is the possibility of mechanical clamping of the blades. The validation is performed by comparing the results with previous studies to show the simulation accuracy. This research’s overall objective is the dynamical simulation of Hunter turbine with the CFX. The turbine was then designed to desired dimensions and simulated in the ANSYS software at a specified fluid flow rate and verified, which had not been done so far.

A comprehensive series of tests have been made on an experimental single‐stage turbine to determine the cooling characteristics and the overall stage performance of a set of air‐cooled turbine blades. These blades, which arc described fully in Part I of this paper had, internally, a multiplicity of passages of small diameter along which cool air was passed through the whole length of the blade. Analysis of the test data indicated that, when a quantity of cooling air amounting to 2 per cent, by weight, of the total gas‐flow through the turbine is fed to the row of rotor blades, an increase in gas temperature of about 270 dcg. C. (518 deg. F.) should be permissible above the maximum allowable value for a row of uncoolcd blades made from the same material. The degree of cooling achieved throughout each blade was far from uniform and large thermal stresses must result. It appears, however, that the consequences of this are not highly detrimental to the performance of the present type of blading, it being demonstrated that the main effect of the induced thermal stress isapparently to transfer the major tensile stresses to the cooler (and hence stronger) regions of the blade. The results obtained from the present investigations do not represent a limit to the potentialities of internal air‐cooling, but form merely a first exploratory step. At the same time the practical feasibility of air cooling is made apparent, and advances up to the present arc undoubtedly encouraging.

Fundamentally, it is advantageous to operate an aeroengine's thermodynamic cycle at as high a turbine entry temperature as practical for the current metallurgical limits of the turbine blades in order to achieve peak cycle efficiency and thus lower specific fuel consumption. However, achieving the highest possible turbine entry temperature requires accurate knowledge of the turbine blade temperatures for control purposes to prolong component life as frequent excursions beyond the design limits of the blades can severely reduce their service life. The optical pyrometry technique represents the best method for providing this crucial temperature data needed for blade condition‐based monitoring. This paper presents the general operating principles, system aspects and design considerations for the application of the optical pyrometer instrument for inflight service use on gas turbine aeroengines.

The purpose of this study a fast procedure for the structural analysis of gas turbine blades in aircraft engines. In this connection, investigations on the behavior of gas turbine blades concentrate on the analysis and evaluation of starting dynamics and fatigue strength. Besides, the influence of structural mistuning on the vibration characteristics of the single blade is analyzed and discussed.

A basic computation cycle is generated from a flight profile to describe the operating history of the gas turbine blade properly. Within an approximation approach for high-frequency vibrations, maximum vibration amplitudes are computed by superposition of stationary frequency responses by means of weighting functions. In addition, a two-way coupling approach determines the influence of structural mistuning on the vibration of a single blade. Fatigue strength of gas turbine blades is analyzed with a semi-analytical approach. The progressive damage analysis is based on MINER’s damage accumulation assuming a quasi-stable behavior of the structure.

The application to a gas turbine blade shows the computational capabilities of the approach presented. Structural characteristics are obtained by robust and stable computations using a detailed finite element model considering different load conditions. A high quality of results is realized while reducing the numerical costs significantly.

The method used for analyzing the starting dynamics is based on the assumption of a quasi-static state. For structures with a sufficiently high stiffness, such as the gas turbine blades in the present work, this procedure is justified. The fatigue damage approach relies on the existence of a quasi-stable cyclic stress condition, which in general occurs for isotropic materials, as is the case for gas turbine blades.

Owing to the use of efficient analysis methods, a fast evaluation of the gas turbine blade within a stochastic analysis is feasible.

The fast numerical methods and the use of the full finite element model enable performing a structural analysis of any blade structure with a high quality of results.

This paper aims to conduct a comprehensive literature review in the tidal energy physics, the ocean environment, hydrodynamics of horizontal axis tidal turbines and bio-mimicry.

The paper provides an insight of the tidal turbine blade design and need for renewable energy sources to generate electricity through clean energy sources and less CO₂ emission. The ocean environment, along with hydrodynamic design principles of a horizontal axis tidal turbine blade, is described, including theoretical maximum efficiency, blade element momentum theory and non-dimensional forces acting on tidal turbine blades.

This review gives an overview of fish locomotion identifying the attributes of the swimming like lift-based thrust propulsion, the locomotion driving factors: dorsal fins, caudal fins in propulsion, which enable the fish to be efficient even at low tidal velocities.

Finally, after understanding the phenomenon of caudal fin propulsion and its relationship with tidal turbine blade hydrodynamics, this review focuses on the implications of bio-mimicking a curved caudal fin to design an efficient horizontal axis tidal turbine.

ALTHOUGH numerous papers and lectures presented to the Royal Aeronautical Society have mentioned the upward trend in turbine inlet gas temperatures, there has been no review of the status of blade cooling technology since 1956, when Ainley's classic paper ‘The High Temperature Turbo‐jet’ was published. Accordingly it is the aim of this paper to present such a review. Before doing so it is worth while to compare the engine situation today with what it was in 1956. At that time, much of the available experience in the U.K. on air cooled turbines was based on experimental units, designed for the express purpose of measuring blade temperatures under controlled conditions of cooling airflow and high gas temperature. These research turbines had also yielded some useful preliminary data on the aerodynamic effects of cooling air discharge and on thermal stress and creep problems. Some engine experience had been attained, mainly (in the U.K.) with engines such as the Avon, Conway and Tyne. Whereas many of the research turbine and cascade blades had fairly complex patterns of relatively small cooling passages, the blades which had been submitted to engine running usually had a few comparatively large passages. Rotating blades were made exclusively by forging and extrusion processes from wrought nickel‐base alloys. Some nozzle guide vanes were cast.

The purpose of this paper is to evaluate the effect of film cooling holes on the vibration characteristics of a turbine blade, and provide the design basis for the blade, which may reduce computing costs.

Modal analysis of the blades with and without film cooling holes is performed to evaluate the effect of film cooling holes on its natural frequency. Harmonic analysis of the blade is performed to calculate the stress concentration factors of film cooling holes for different modes.

The frequency differences between two blades with and without film cooling holes are insignificant, while the differences of the vibration stress cannot be neglected. For the first three modes of the blades, the stress concentration factor is sensitive to the hole’s shape and position on the blade. With the help of the stress concentration factor defined in this work, the concentration of stresses induced by different film cooling holes can be accurately described when evaluating HCF life of the turbine blade.

The effect of film cooling holes on a turbine blade's natural frequencies was confirmed to be insignificant and the stress concentration factors around the holes are calculated. Therefore, the simplified model of the blade without film cooling holes can be used to evaluate the natural frequencies and vibration stress, which saves a lot of time and cost.

Wind turbines are one of the best candidates to solve the problem of increasing energy demand in the world. The aim of this paper is to apply a multi-objective structural optimization study to a Phase II wind turbine blade produced by the National Renewable Energy Laboratory to obtain a more efficient small-scale wind turbine.

To solve this structural optimization problem, a new Non-Dominated Sorting Genetic Algorithm (NSGA-II) was performed. In the optimization study, the objective function was on minimization of mass and cost of the blade, and design parameters were composite material type and spar cap layer number. Design constraints were deformation, strain, stress, natural frequency and failure criteria. ANSYS Composite PrepPost (ACP) module was used to model the composite materials of the blade. Moreover, fluid–structure interaction (FSI) model in ANSYS was used to carry out flow and structural analysis on the blade.

As a result, a new original blade was designed using the multi-objective structural optimization study which has been adapted for aerodynamic optimization, the NSGA-II algorithm and FSI. The mass of three selected optimized blades using carbon composite decreased as much as 6.6%, 11.9% and 14.3%, respectively, while their costs increased by 23.1%, 29.9% and 38.3%. This multi-objective structural optimization-based study indicates that the composite configuration of the blade could be altered to reach the desired weight and cost for production.

ACP module is a novel and advanced composite modeling technique. This study is a novel study to present the NSGA-II algorithm, which has been adapted for aerodynamic optimization, together with the FSI. Unlike other studies, complex composite layup, fiber directions and layer orientations were defined by using the ACP module, and the composite blade analyzed both aerodynamic pressure and structural design using ACP and FSI modules together.

This paper aims to present the designing and investigating various types of impulse blade profiles to find the optimal profile that has better performance than the first or original blade. The studied model is a turbine with an output power below 1 MW and a large pressure ratio up to 20, which is used to gain relatively high specific work output. As a result of its low mass flow rate, the turbine is used under partial-admission conditions. The turbine’s stator is a group of convergence–divergence nozzles that provide supersonic flow.

More than 10 types of two-dimensional blade profiles were designed using the developed preliminary design calculations and numerical analysis. The numerical results are validated using the existing experimental results. Finally, the case with improved performance is introduced as the final optimum case.

It was found that the performance parameters such as efficiency, power and torque are increased by more than 8% in the selected best model, in comparison with the original model. Moreover, the total pressure loss is 12% decreased for the selected model. Finally, the selected profile with superior performance is proposed.

Simultaneous numerical tests are conducted to examine the interaction of different supersonic blade profiles with the partially injected flow to the rotor.

Based on aerodynamic analysis, an optimization method for the profiles of turbine blade is studied in this paper. This method is capable of addressing multiple objectives and constrains without relying on user input. A quintic polynomial is used to build the three‐dimensional blade model and a three dimensional Navier‐Stokes solver was used to solve the flow field around the turbine blade. The objective functions are the turbine aerodynamic efficiency and total pressure ratio. The optimization is completed with the K‐S function technique and accelerated by approximation technique. Finally, the proposed method is applied to optimizing a true blade to validate its accuracy and efficiency. The obtained result shows that the approximation method is more efficient and accurate than the conventional method.