Shape optimization of a Savonius wind rotor with different convex and concave sides

Reliability improvement of wind turbine power generation using model-based fault detection and fault tolerant control: A review

Urban-wildland fires have plagued the United States for centuries. Recent urban-wildland fires include the 2002 Hayman Fire, the 2000 Los Alamos Fire, and the 1991 Oakland Hills Fire [1]. Fires in the urban wildland interface can have a devastating effect on human life, property loss, and local economies. Embers or firebrands are produced as trees and other objects burn in urban-wildland fires. These firebrands are entrained in the atmosphere and may be carried by winds over long distances. Hot firebrands ultimately come to rest and may ignite fuels far removed from the fire, resulting in fire spread. This process is commonly referred to as spotting. Understanding how these hot firebrands can ignite surrounding fuels is an important consideration in mitigating fire spread in communities. A major advance in urban-wildland fire research would be the development of a model to predict the ignitability of materials due to firebrand impact [2]. The lack of a detailed theory on the ability of firebrands to ignite remote objects limits the utility of detailed computational fluid dynamic models (CFD) that could be used to predict fire spread by firebrands [2]. Detailed experimental ignition studies of fuel beds typically found in the urban-wildland interface due to firebrand impact are required to validate such models. Consequently, an experimental apparatus has been built to investigate the ignition of fuel beds as a result of impact with burning firebrands. The apparatus allowed for the ignition and deposition of firebrands onto the target fuel bed. The moisture content of the fuel beds used was varied and the fuels considered were pine needle beds and shredded paper beds. Pine needle beds were intended to simulate gutters filled with pine needles. Shredded paper beds were used as a surrogate for typical cellulosic fuels that would be found in attic spaces. Firebrands were simulated by machining wood (pinus ponderosa) into small disks of uniform geometry. The firebrand ignition apparatus was installed into the Fire Emulator/Detector Evaluator (FE/DE) to investigate the influence of an air flow on the ignition propensity of fuel beds. Results of this study are presented.

Urban-Wildland Fires: On the Ignition of Fuel Beds by Firebrands. (POSTER ABSTRACTS) | NIST

Optimal shape of thick blades for a hydraulic Savonius turbine

Review of savonius wind turbine design and performance

It has been suggested that waste heats or naturally available heat sources can be utilized to produce swirling flow by a design similar to that of split channels which is currently used to initiate fire whirls in laboratories. The new design combines the conventional Savonius wind turbine and split channel mechanisms. Previous computational and preliminary experimental works indicate a performance improvement in the new design (named as swirling Savonius turbine) compared to the conventional Savonius design. In this study, wind tunnel experiments have been carried out to optimize the swirling Savonius turbine geometry in terms of maximum power coefficient by considering several design parameters. The results indicate that the blade overlap ratio, hot air inlet diameter and the condition of the top end plate have significant influence on power and torque coefficients, while a larger aspect ratio and closed top end plate have some favourable effects on the performance. The optimum configuration has been tested in four different wind velocities to determine its influence on the performance, and power coefficients were found to be higher in high wind velocities. The performance comparison of optimum configuration with conventional Savonius rotor showed an increase of 24.12% in the coefficient of power.

Geometrical optimization of a swirling Savonius wind turbine using an open jet wind tunnel

Flow Field and Performance Study of Vertical Axis Savonius Type SST Wind Turbine

Research on wind turbine technologies have focused primarily on power cost reduction. Generally, this aim has been achieved by increasing power output while maintaining the structural load at a reasonable level. How- ever, disturbances, such as wind speed, affect the performance of wind turbines, and as a result, the use of various types of controller becomes crucial.

This paper deals with two adaptive fuzzy controllers at full load operation. The first controller uses the generated power, and the second one uses the angular velocity as feedback signals. These feedback signals act to control the load torque on the generator and blade pitch angle. Adaptive rules, derived from the fuzzy controller, are defined based on the differences between state variables of the power and angular velocity of the generator and their nominal values.

The results, which are compared with verified results of reference controller, show that the proposed adaptive fuzzy controller in full load operation has a higher efficiency than that of reference ones, insensitive to fast wind speed
variation that is considered as disturbance.

http://ijfs.usb.ac.ir/pdf_2428_308f6f0e85ce1f925dc3c630db3c4b78.html

Power and velocity control of wind turbines by adaptive fuzzy controller during full load operation

Previous studies have shown the effectiveness of low porosity and double-layer screens against
radiant heat flux from fires. The performance of screens against firebrand attack is also required
to be assessed prior to making a decision on their possible application in wildland fire prone areas.
The available laboratory-scale devices simulate firebrands at wind speeds less than those of severe
firebrand attacks. A relatively low cost, laboratory-scale fire ember shower simulator has been
designed and manufactured in-house. The simulator is able to assess the performance of low porosity
screens at high wind speeds without any reverse flow and possible consequent safety hazards
and offers reasonable control over the size and mass of the generated firebrands.

/pdf/a-novel-ember-shower-simulator-for-assessing-performance-of-2a88hxnoj1.pdf

A novel ember shower simulator for assessing performance of low porosity screens at high wind speeds against firebrand attacks

Wind tunnel experiments were carried out on a geometrically optimal swirling Savonius turbine by varying flow parameters to determine their effects on power and torque coefficients. The optimum geometrical configuration used in this experiment was adopted from an earlier study that features 0.20 blade overlap ratio, 195˚ blade arc angle, and 1.06 rotor aspect ratio of a 320 mm diameter rotor with closed top end plate. The parameters considered in this experimental are the hot air temperature, hot air mass flow rate, hot air inlet diameter of swirl chamber, and the free-stream wind velocity. The results indicate that higher hot air temperature and hot air mass flow rate promotes performance of the turbine while power coefficient reached maximum at a certain hot air inlet diameter. Tests on the optimum geometry at four wind velocities revealed that power coefficients are higher in higher wind velocities.

/pdf/effects-of-flow-parameters-on-the-performance-of-vertical-64ynndz1no.pdf

Ahmad Sharifian

Papers

Geometrical optimization of a swirling Savonius wind turbine using an open jet wind tunnel

Flow Field and Performance Study of Vertical Axis Savonius Type SST Wind Turbine

Power and velocity control of wind turbines by adaptive fuzzy controller during full load operation

A novel ember shower simulator for assessing performance of low porosity screens at high wind speeds against firebrand attacks

Effects of flow parameters on the performance of vertical axis swirling type Savonius wind turbine