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Ahmad Sharifian

Bio: Ahmad Sharifian is an academic researcher from University of Southern Queensland. The author has contributed to research in topics: Wind speed & Refrigerant. The author has an hindex of 5, co-authored 33 publications receiving 124 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, 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, such as blade overlap ratio, hot air inlet diameter and the condition of the top end plate.
Abstract: 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.

32 citations

Journal ArticleDOI
TL;DR: In this paper, a new hybrid power system has been proposed combining the conventional Savonius wind turbine and split channel mechanisms, and a simulation method for predicting their aerodynamic performance using control volume based CFD package of ANSYS CFX.

26 citations

Journal ArticleDOI
TL;DR: 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.
Abstract: 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.

10 citations

Journal ArticleDOI
TL;DR: In this article, a low-cost laboratory-scale fire ember shower simulator has been designed and manufactured in-house, which is able to assess the performance of low porosity screens at high wind speeds without any reverse flow and possible consequent safety hazards.
Abstract: 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.

10 citations

Journal ArticleDOI
TL;DR: In this paper, 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.
Abstract: 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.

7 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a modified Savonius rotor with different convex and concave sides is optimized to maximize the power efficiency, and a particle swarm optimization (PSO) algorithm is applied to find the optimal design based on the response surface model.

127 citations

Journal ArticleDOI
TL;DR: A comprehensive review of the most-recent model-based fault detection and fault tolerant control schemes for wind turbine power generation is presented, focusing on the advantages, capabilities and limitations.

114 citations

01 Sep 2005
TL;DR: In this paper, an experimental apparatus has been built to investigate the ignition of fuel beds as a result of impact with burning firebrands, which can be used to predict fire spread in urban wildland fires.
Abstract: 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.

89 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed an optimal shape of the concave and convex sides of a hydraulic Savonius turbine to maximize the output power of the turbine by modifying the blade profile.

84 citations

Journal ArticleDOI
TL;DR: In this paper, the Savonius rotor was used to improve the performance of a wind turbine by optimizing the effects of different geometric parameters and by developing new design, which achieved an improvement in the coefficient of performance of 27.3% compared to the conventional rotor.

83 citations