Loading and Design Parameter Uncertainty in the Dynamics and Performance of High-Speed-Parallel-Helical-Stage of a Wind Turbine Gearbox1

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Design Parameter ◽  
High Speed ◽  
Design Parameters ◽  
Parameter Uncertainties ◽  
Component Reliability ◽  
Input Shaft ◽  
Multibody Dynamic ◽  
Input Variables ◽  
And Performance

In operation, wind turbine gearboxes (WTGs) are subjected to variable torsional and nontorsional loads. In addition, the manufacturing and assembly process of these devices results in uncertainty in the design parameters of the system. WTGs are reported to fail in their early life of operation within 3–7 years as opposed to the expected 20 years of operation. Their downtime and maintenance process is the most costly of the failures of any subassembly of wind turbines (WTs). The objective of this work is to perform a probabilistic multibody dynamic analysis (PMBDA) of the high-speed-parallel-helical-stage (HSPHS) of a WTG that considers the uncertainties of generator-side torque-loading and input-shaft speed as well as assembly and design parameter uncertainties. Component reliability (Rc) or probability of failure (Pf) and probabilistic sensitivities of all the input variables toward five performance functions have been measured and conclusions have been drawn. As opposed to the traditional deterministic approach, PMBDA has demonstrated a new aspect of design and installation of WTGs. In addition to revealing Rc or system reliability or underperformance through Pf, the method will also help designers to critically consider certain variables through the probabilistic sensitivity results.

Loading and Design Parameter Uncertainty in the Dynamics and Performance of High-Speed-Parallel-Helical Stage of a Wind Turbine Gearbox

2013 ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Parameter Uncertainty ◽  
System Reliability ◽  
Design Parameter ◽  
High Speed ◽  
Probability Of Failure ◽  
Wind Turbine Gearbox ◽  
Input Shaft ◽  
Input Variables ◽  
And Performance

The Wind Turbine Gearboxes (WTGs) are highly subjected to variable torsional and non-torsional loads. In addition, the manufacturing and assembly process of these devices results in uncertainty in the system. These gearboxes are reported to fail in their early life of operation, within three to seven years as opposed to the expected twenty years of operation. Their downtime and maintenance process is the most costly of any failure of subassembly of wind turbines. The objective of this work is to perform a probabilistic multibody dynamic analysis (PMBDA) of the high-speed-parallel-helical stage of the gearbox of wind turbine that considers uncertainty of generator side torque loading and the input shaft speed, assembly errors and design parameter uncertainty. System reliability, probability of failure, and probabilistic sensitivities of all the input variables towards several performance functions have been measured and conclusions have been drawn. PMBDA has demonstrated a new dimension of design and installation of wind turbine gearboxes than traditional deterministic approach. In addition to revealing system reliability or under-performance through probability of failure, the method will also help designers to consider certain variables critically through the sensitivity results.

Probabilistic Performance of Helical Compound Planetary System in Wind Turbine

2015 ◽  
Vol 10 (4) ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Multibody Systems ◽  
Planetary System ◽  
Design Parameters ◽  
Wind Turbine Gearbox ◽  
New Approach ◽  
Highly Nonlinear ◽  
Multibody Dynamic ◽  
Input Variables ◽  
Maintenance Process

The dynamics of contact, stress and failure analysis of multibody systems is highly nonlinear. Nowadays, several commercial and other analysis software dedicated for this purpose are available. However, these codes do not consider the uncertainty involved in loading, design, and assembly parameters. One of these systems with a combined high nonlinearity and uncertainty of parameters is the gearbox of wind turbines (WTs). Wind turbine gearboxes (WTG) are subjected to variable torsional and nontorsional loads. In addition, the manufacturing and assembly process of these devices results in uncertainty of the design parameters of the system. These gearboxes are reported to fail in their early life of operation, within three to seven years as opposed to the expected twenty years of operation. Their downtime and maintenance process is the most costly of any failure of subassembly of WTs. The objective of this work is to perform a probabilistic multibody dynamic analysis (PMBDA) of a helical compound planetary stage of a selected wind turbine gearbox that considers ten random variables: two loading (the rotor speed, generator side torque), and eight design parameters. The reliability or probabilities of failure of each gear and probabilistic sensitivities of the input variables toward two performance functions have been measured and conclusions have been drawn. The results revealed that PMBDA has demonstrated a new approach of gear system design beyond a traditional deterministic approach. The method demonstrated the components' reliability or probability of failure and sensitivity results that will be used as a tool for designers to make sound decisions.

Aerodynamic and aeroacoustic performance investigations on modified H-rotor Darrieus wind turbine

2021 ◽  
pp. 0309524X2110039
Author(s):  
Amgad Dessoky ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Wind Turbine ◽  
High Speed ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
3D Models ◽  
Power Coefficient ◽  
Design Parameters ◽  
Second Phase ◽  
Vertical Axis Wind Turbine ◽  
Guide Vanes

The present paper investigates the aerodynamic and aeroacoustic characteristics of the H-rotor Darrieus vertical axis wind turbine (VAWT) combined with very promising energy conversion and steering technology; a fixed guide-vanes. The main scope of the current work is to enhance the aerodynamic performance and assess the noise production accomplished with such enhancement. The studies are carried out in two phases; the first phase is a parametric 2D CFD simulation employing the unsteady Reynolds-averaged Navier-Stokes (URANS) approach to optimize the design parameters of the guide-vanes. The second phase is a 3D CFD simulation of the full turbine using a higher-order numerical scheme and a hybrid RANS/LES (DDES) method. The guide-vanes show a superior power augmentation, about 42% increase in the power coefficient at λ = 2.75, with a slightly noisy operation and completely change the signal directivity. A remarkable difference in power coefficient is observed between 2D and 3D models at the high-speed ratios stems from the 3D effect. As a result, a 3D simulation of the capped Darrieus turbine is carried out, and then a noise assessment of such configuration is assessed. The results show a 20% increase in power coefficient by using the cap, without significant change in the noise signal.

Probabilistic Multibody Modeling of Gearboxes for Wind Turbines

2011 ◽  
Author(s):  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Loading ◽  
Design Parameters ◽  
Probabilistic Design ◽  
Deterministic Approach ◽  
Early Failure ◽  
Multibody Modeling ◽  
Design Life ◽  
Multibody Dynamic

Gearboxes have been prone to early failure rather than any mechanical part of modern wind turbines, much earlier than their predicted design life. Some studies indicated that gearboxes of wind turbines fail during the first 3 to 5 years of operation of the system as opposed to the total design life of the wind turbine, which usually is 20 years. Consequently, such failures cause the highest down time and extremely expensive replacement activities. Gearboxes are subjected to torsional, bending and axial wind loads which are yet not fully defined. The uncertainty in loading conditions and system design parameters has brought about the importance of considering probabilistic design and modeling approach than the traditional deterministic approach. Accordingly, the motivation of this study is to improve the reliability of gearboxes for wind turbine applications. A probabilistic multibody dynamic modeling of the gearbox, that fully integrates uncertainties in wind loading and design parameters, is sought. This paper presents previous studies and finally proposes the above mentioned approach as a potential way of improving, in general, the reliability of wind energy and, in particular, the gearboxes in wind turbines.

Research and Development of Minitype Twin-Bladed Air Turbine

2009 ◽  
Author(s):  
Shih-Chun Wang ◽  
Kuang-Yuh Huang
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Design Parameters ◽  
Operational Parameters ◽  
Micro Fabrication ◽  
Air Turbine ◽  
Speed Performance ◽  
Operational Energy ◽  
And Performance

In order to improve the machining efficiency of ultra-precision and micro fabrication technology, a high speed spindle is essential for the minitype tools widely applied in systems such as PCB drilling machines, micro fabrication machines, dental handpieces, etc. To realize the high speed performance, the air driven turbine is verified to be more feasible than the electromagnetic actuator. Furthermore, the operational efficiency and quality of the high speed spindle are significantly influenced by the turbine blades and the bearings respectively. Through detailed configurational studies and performance analyses on diverse minitype turbine blades, we have derived the efficiency- and quality-influential parameters. And based on optimization results, we have developed a novel type of twin bladed air turbine (TB-air turbine), which consists of two parallel blades with an angular offset. The offseted twin blades can efficiently and smoothly transform pneumatic energy into rotational energy. Therefore, steady driving force and less dynamic unbalance are able to be easily achieved for reducing nervous disturbances such as vibration, noise, and wear. By applying finite element analytical method, the operational performances and quality of the new developed twin bladed air turbine such as rotational speed, torque, vibration and noise were analyzed for comprehending influences of the design parameters and the operational parameters. While the inlet angle, the blade shape and its geometric parameters are the dominant design parameters; the inlet pressure and mass flow rate, and the outlet pressure are the main operational parameters. Through the turbine blades, the pneumatic energy will be transformed into operational energy in form of the flow field and the pressure distribution and the energy loss in form of turbulence. Also by integrating knowledge of production technology, a neat design of the turbine blades suitable for automatic manufacturing process is developed. And furthermore, through an elaborate layout of the flow guiding, a minimum rotational runout can be effectively achieved without any complicate and costly dynamic balancing process. Consequently, it has significantly depressed the stream noise and raised the operation lifetime of bearings. According to our experimental verification, the vibration and the stream noise of our TB-air turbines are 60% and 50% lower than traditional counterparts respectively. Our developed minitype spindle with novel TB-air turbine can efficiently realize high speed rotation with high torque, less vibration and less noise.

Selection of One-Dimensional Design Parameter ‘Reaction Degree’ for 1st Stage of a Cooled Gas Turbine

2012 ◽  
Author(s):  
Hina Noor ◽  
Magnus Genrup ◽  
Torsten Fransson
Keyword(s):  
Mass Flow ◽  
Design Parameter ◽  
Design Tool ◽  
Performance Estimation ◽  
Design Parameters ◽  
Flow Angle ◽  
One Dimensional ◽  
And Performance ◽  
Reaction Degree ◽  
Selection Of

The recommendations available today in open literature for the choice of design parameter such as flow coefficient, stage loading and reaction degree incorporates mainly the influence of aerodynamics loss on efficiency. However, it is difficult to find the recommendation relating the influence of not only the aerodynamics loss but also cooling mass flow and cooling losses on varying most influential design parameters. In this paper, preliminary design and performance guidelines are presented for a cooled turbine stage using the 1D design tool LUAXT. The intention is to provide recommendations on the selection of design parameters, mainly reaction degree, which is found to be highly influenced by not only the aerodynamics loss but also the cooling mass flow and cooling loss such as in 1st stage of a High Pressure Turbines (HPT). The One-Dimensional (1D) design methods used to perform this task are verified and validated against experimental test data. A comparison of different loss models has been performed to provide most accurate outcomes for certain tested ranges. Based on the outcomes of this study, ‘Craig & Cox’ loss model has been considered to perform subsequent investigations for HPT design and performance estimation while formulating a parametric study. From this study, the design recommendations for the selection of performance parameter reaction degree are developed for cooled turbines. The results shows that for a HPT 1st stage, the recommended reaction degree range of 0.20 to 0.37 seems to provide the optimum stage design when chosen for stage loading in between 1.40 to 1.80 along with the stator exit flow angle in range of 74° to 78°.

Design Parameter Sensitivity for a Mountain Bike Rear Shock

2006 ◽  
Author(s):  
Robin C. Redfield
Keyword(s):  
High Speed ◽  
Current Trend ◽  
Graph Model ◽  
Bond Graph ◽  
Design Parameters ◽  
Mountain Biking ◽  
Mountain Bike ◽  
Suspension Systems ◽  
Experimental Response ◽  
And Performance

As the sport of mountain biking matures, equipment continually evolves to afford better biking performance, enjoyment, and safety. In the arena of suspension systems, mountain bikes have moved from rigid suspensions with large, knobby tires to front fork suspensions, and finally full suspensions. Suspensions have gone from elastomeric compliance to air and coil springs with adjustable travel. Damping has progressed from fixed to adjustable rebound, compression, and lockout. The current trend is to add force or frequency dependent damping to minimize response of a suspension from pedal input. A bond graph model of a mountain bike rear shock is developed incorporating adjustable rebound and low-speed compression, high-speed compression, and rider controlled, compression damping initiation. An air shock with a nitrogen charge is modeled with velocity across the shock as input. The dynamic equations that come from the bond graph are simulated to predict key forces, pressures, and flow-rates. Experimental response (forces, displacements, and velocities) of the modeled shock is acquired subject to periodic velocity inputs. The experimental response is used to tune the design parameters of the model and for validation. A sensitivity analysis is then undertaken to determine how significant key design parameters are to the performance of the shock. Once validated, the model is used to better understand the physics and performance of the mountain bike shock and to relate performance to the requirements of expert mountain bikers.

scholarly journals Fabrication and Performance Evaluation of Savonious Vertical Axis Wind Turbine for Uncertain Speed Regions

2017 ◽  
Vol 13 (2) ◽  
Keyword(s):  
Performance Evaluation ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Vertical Axis ◽  
Design Parameters ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
And Performance

The consumption of electricity in urban as well as rural is increasing every day and became an essential commodity for household and industrial purposes. Unfortunately the availability of electrical energy in India is not sufficient to the required demand and it is essential to discover and generate energy from non-conventional sources with cheap cost. On the same time it is necessary to reduce the consumption of conventional sources and to save fuel. Among all the renewable resources, wind is one of the best resources available all the time at free of cost. Especially vertical axis wind turbines (VAWT) are self-starting, omni directional. They require no yaw mechanism to continuously orient towards the wind direction and provide a more reliable energy conversion technology, as compared to horizontal axis wind turbine. Particularly savonius vertical axis wind turbines (SVAWT) are suitable and practically possible at low or uncertain wind speed regimes. They can be fitted on rooftops and also suitable for the urban areas where electricity is not available properly. This project deals with the fabrication and performance evaluation of savonius vertical axis wind turbine using two blade rotor. The amount of power developed by the wind turbine is calculated under theoretical and practical conditions and aerodynamics coefficients are also estimated. And various design parameters of savonious rotor are identified and determined.

An Analysis of Rigid Sidewall Surface Effect Craft for High-Speed Personnel Transportation

1970 ◽  
Vol 7 (01) ◽  
pp. 55-68
Author(s):  
Eugene R. Miller
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Transportation Cost ◽  
Total Power ◽  
Design Parameters ◽  
Economic Criterion ◽  
Calm Water ◽  
And Performance ◽  
Commercial Applications ◽  
Sidewall Surface

A number of commercial applications have been proposed for rigid sidewall surface effect craft. The transport of crews to offshore operations is an application which is well-suited to the immediate use of moderately sized craft of this type. Because the crews are paid while they are in transit, high speeds are required to minimize the total transportation costs. The characteristics and performance of rigid sidewall surface effect craft suitable for crew transport operations are developed. The major design parameters studied include pay-load, total power, and machinery type. Performance estimates are made for operations in both calm water and waves. An economic model is developed to simulate crewboat operations. Cost estimates are based on current technology and price levels. The total unit transportation cost is used as the economic criterion in the determination of the relative merit of various craft. For the purpose of comparison the characteristics and costs of planing hull crewboats for the same mission are developed. It is concluded that rigid sidewall surface effect craft have the potential of being economically superior to planing boats for crew transport operations.

Hybrid-model-based stiffness analysis of a three-revolute-prismatic-spherical parallel kinematic machine

2016 ◽  
Vol 231 (14) ◽  
pp. 2561-2576 ◽  
Author(s):  
Jun Zhang ◽  
Yan Q Zhao ◽  
Hai W Luo
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Design Parameters ◽  
Parallel Kinematic Machine ◽  
Modeling Methodology ◽  
Parallel Kinematic ◽  
Stiffness Characteristics ◽  
And Performance ◽  
High Dynamics ◽  
Spring Constants

A three-revolute-prismatic-spherical parallel kinematic machine is proposed as an alternative solution for high-speed machining tool due to its high rigidity and high dynamics. Considering the parallel kinematic machine module as a typical compliant parallel mechanism, whose three limb assemblages have bending, extending and torsional deflections, this article proposes a hybrid modeling methodology to establish an analytical stiffness model for the three-revolute-prismatic-spherical device. The developed analytical model is further used to evaluate the stiffness mapping of the three-revolute-prismatic-spherical module over a given work plane which is then validated by experimental tests. The simulations and experiments indicate that the present hybrid methodology can predict the three-revolute-prismatic-spherical parallel kinematic machine’s stiffness in a quick and accurate manner. The solution for eigenvalue problem of the stiffness matrix leads to the stiffness characteristics of the parallel module including eigenstiffnesses and the corresponding eigenscrews as well as the equivalent screw spring constants. Based on the eigenscrew decomposition, the parallel kinematic machine is physically interpreted as a rigid platform suspending by six screw springs. The minimum, maximum and average of the screw spring constants are chosen as indices to assess the three-revolute-prismatic-spherical parallel kinematic machine’s stiffness performance. The distributions of the proposed indices throughout the workspace reveal a strong dependency on the mechanism’s configurations. At the final stage, the effects of some design parameters on system stiffness characteristics are investigated with the purpose of providing useful information for the conceptual design and performance improvement of the parallel kinematic machine.

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