Negative Angle Research Articles

Influences of runner blade shape on the transient behaviours of pump-turbines in load rejection

The transient behaviour of the pump-turbine in load rejection is very complex, and slight changes in runner blade shape may have great influence on it. To understand the underlying flow mechanisms, the load rejection processes of two model pump-turbines with the same specific-speed but different in the runner blade inlet shape were investigated by a three-dimensional numerical simulation method. The results show that the lean angle of the runner blade leading edge impacts the evolution of backflows at the runner inlet. The backflows first emerge at the shroud side for the runner with a negative lean angle, and the backflows first emerge at the hub side for the runner with no lean angle. However, the backflows at the shroud side make more imbalanced flows in the runner passages and higher increase of pressure fluctuations in the vaneless space. As a consequence, greater radial force fluctuations on the runner blades are formed.

Effect of inclination angle on the thermal performance of an ultrathin heat pipe with multi-scale wick structure

In this study, a multi-scale copper mesh wick structure fabricated by oxidation treatment and sintering is proposed for increasing the heat transport capabilities of ultrathin heat pipes (UTHPs). Experimental apparatus and a thermal resistance network model were established to analyse the heat transfer characteristics of UTHPs. The effects of various heating loads and negative inclination angles on the thermal performance of a UTHP with an oxidised mesh wick (OMHP) were experimentally investigated. The results were compared with those of an untreated mesh wick ultrathin heat pipe (NMHP) and a sintered powder wick ultrathin heat pipe (CPHP). The experimental results demonstrate that the heat transport capabilities of UTHPs with a mesh wick in the horizontal and inclined orientations were enhanced significantly owing to oxidation. The oxidised mesh wick exhibited the same or better capillary performance as the sintered powder wick in inclined orientations. Moreover, when the inclination angle increased to 90°, the temperature difference of OMHP was 36.4% and 26% lower than that of OMHP and CPHP, respectively, under the input power of 14 W. The thermal resistances of OMHP were lower than those of NMHP (by approximately 57%) and CPHP under identical test conditions.

Low Risk of Wound Complications with Sinus Tarsi Approach for Treatment of Calcaneus Fractures

Category:Trauma; HindfootIntroduction/Purpose:Fractures of the calcaneus are life-changing events with a major socioeconomic impact from lost productivity. Traditional operative treatment with the extensile lateral approach has shown relatively high rates of wound complications. Less invasive approaches can improve fracture alignment and decrease wound healing complications. The purpose of this study is to report our experience with the sinus tarsi approach in treating calcaneus fractures.Methods:We retrospectively identified patients at our institution treated with a limited sinus tarsi approach for calcaneus fractures from 2009-2018. Demographic and radiographic data were collected including: age, sex, mechanism of injury, occupation, presence of diabetes, smoking status, Sanders classification, Bohler and Gissane angles. Postoperatively, we recorded the presence of complications, return-to-work time, and radiographic measurements.Results:Our analysis included 105 fractures in 100 patients: 86% males, 42% smokers, 4% diabetics, with an average body mass index of 26.5. The fractures were: Sanders type 2 (32%), type 3 (48%), type 4 (18%), and 2% were a tongue-type variant. Preoperatively 38% of fractures displayed a negative angle, 50% had an angle 0-20 degrees, and 12% over 20 degrees; postoperatively 13% had an angle 0-20 degrees, and 87% had an angle over 20 degrees. Of patients working prior to the injury, 72% had returned to work by 6 months, and 89% by 12 months. The wound complication rate was 12% (12/100), with only 2% (2/100) requiring additional procedures. There was no significant difference in wound complication rates in smokers versus nonsmokers (11.9% vs 12.2%, p=0.55).Conclusion:The limited sinus tarsi approach for depressed calcaneus fractures allows radiographic restoration of calcaneal height with a low rate of wound complications, even amongst active smokers. To the authors’ best knowledge, this is the largest published case series of calcaneus fractures treated with the sinus tarsi approach. Further follow up is needed to determine the success of this approach in mitigating long term complications.

Aeroelastic behaviour of a wing with over-the-wing mounted UHBR engine

The aeroelastic behaviour of a wing with an over-the-wing pylon-mounted ultra-high bypass ratio engine and high-lift devices is studied with a reduced-order model. Wing, pylon and engine structures are reduced separately using the modal approach and described by their natural frequencies and modes. The characteristic aerodynamic loads are investigated with steady and unsteady flow simulations of a two-dimensional profile section. These results indicate possible heave instabilities at strongly negative angles of attack. Three-dimensional effects are taken into account using an adapted lifting line theory according to Prandtl. Due to high circulations resulting from the high-lift systems, the effective angles of attack are in the range of the potential instabilities. The substructures and aerodynamic loads are coupled in modal space. For the wing without three-dimensional effects, the bending instability occurs at the corresponding negative angles of attack. Even though there is potential for improvement, including the three-dimensional effects shifts the endagered area to possible operation points.

An experimental study on the effect of tool geometry on tool wear and surface roughness in hard turning

The main purpose of this study is to investigate the influence of tool geometry (cutting edge angle, rake angle, and inclination angle) and to optimize tool wear and surface roughness in hard turning of AISI 1055 (52HRC) hardened steel by using TiN coated mixed ceramic inserts. The results show that the inclination angle is the major factor affecting the tool wear and the surface roughness in hard turning. With the increase in negative rake and inclination angles, the tool wear decreases, and the surface roughness increases. However, the surface roughness will decrease when the inclination angle increases to overpass a certain limit. This is a new and significant point in the research of the hard turning process. From this result, the large negative inclination angle (λ = −10°) should be applied to reduce the surface roughness and the tool wear simultaneously. With the optimal cutting tool angles in the research, the hard machining process is improved remarkably with decreases of surface roughness and tool wear 8.3% and 41.3%, respectively in comparison with the standard tool angles. And the proposed tool-post design approach brings an effective method to change the tool insert angles using standard tool-holders to improve hard or other difficult-to-cut materials turning quality.

ТЕПЛОТРАНСПОРТНАЯ СПОСОБНОСТЬ ФИТИЛЯ ИЗ МЕТАЛЛИЧЕСКИХ СЕТОК

In the manufacture of wicks for capillary transport of coolant in various heat transfer devices such as heat pipes, capillary pumped loop, accumulators with thermal regulation, evaporative heat exchangers, heat sinks, etc., capillary porous structures are used. Capillary and porous structures made of compressed powders (metal or non-metal) are widely used. However, the technology of making such porous structures is complicated and time-consuming. Important requirements for wicks are high capillary pressure, low-pressure drop, low weight, and manufacturability. Capillary porous structure, which meets these requirements, can be a wick made of several layers of metal mesh, superimposed on each other, and connected by contact welding. The main advantages of such wicks are low weight and ease of fabrication. The article deals with the methods and results of determining the limit heat transfer capacity of a free wick (not in contact with solid walls) of metal meshes. The design of an experimental unit is given, which allows testing not only at positive but also at small negative angles of the wick to the horizon. Experiments on ammonia to determine the limit heat transport capacity of a flat free wick made of two-layer metal mesh 0.2×0.13 mm woven weave is conducted. By results of the spent experiments dependence of limiting the heat-transport ability of a wick from the temperature of saturation of the heat carrier and an angle of slope to the horizon is received. The performed experiments allow for a wick of the given design to calculate its maximum heat-transport capacity in earth conditions at any width, a transport length of a wick, and an angle of slope to the horizon. Formulas for calculating the thermal transport capacity of wicks made of metal mesh of different length and width under microgravity conditions and in the field of gravity of the earth at different orientations are recommended. The results of the experiments allow determining the thermal transport capacity of wicks from metal meshes and in microgravity conditions.

Conveying performance of drilling tool of auger miner at different strike angles based on discrete element method

The effect of strike angle on the conveying performance of drilling tools was studied using the discrete element method for efficient, reliable and economical auger mining. The results show that there are significant differences in volume fill level and power among the rows of drilling rods and drilling heads at any strike angles. It is necessary to take steps in the retreat process to improve the recovery ratio of the drilling tool. In addition, the increasing positive strike angle and increasing negative strike angle have opposite effects on the overall conveying performance of a drilling tool. To provide the drilling tool with consistent conveying performance, the screw twist direction and rotation direction of the middle drilling rod and middle drilling head should be designed according to the sign of the strike angle. This research has important guiding significance and practical value for the structural design and optimization of drilling tools.

An alternative aerodynamic mitigation measure for improving bridge flutter and vortex induced vibration (VIV) stability: Sealed traffic barrier

This study proposes an alternative aerodynamic mitigation measure, i.e., sealed traffic barrier, for bridges and verifies its efficacy in improving the flutter and vortex induced vibration (VIV) stability of bridges through wind tunnel tests for three distinctive real-world bridge projects. The results show that: (1) The measure of the sealed traffic barrier with regular intervals along the bridge deck has a significant influence on the flutter and VIV performance of the bridge. Thus, a reasonable design of the traffic barrier can simultaneously improve the bridge’s flutter and VIV stability; (2) The sealed traffic barrier with vertical intervals along the bridge can effectively suppress the vertical VIVs of the bridge, while the sealed traffic barrier without vertical intervals, i.e., configured continuously along the bridge, has a better vibration suppression effect on the torsional VIV than that on the vertical VIV; (3) This proposed measure installed on both sides of the bridge deck imposes favorable suppression effect for the flutter vibration, similar to the upward central stabilizer. In case with the sealing form fixed, but a reduced height, for the barrier, the flutter stability at different wind attack angles is slightly decreased; and (4) In certain scenarios, increasing the ventilation rate of the traffic barrier results in an increase for the flutter critical wind speed at positive wind attack angles, but a decrease for the flutter critical wind speed at negative wind attack angles. This aerodynamic mitigation measure has been successfully applied to more than ten other bridge projects based on the wind tunnel tests by the leading authors, offering a reliable approach in improving both flutter and VIV for bridges.

Improved Lunar Irradiance Model Using Multiyear MODIS Lunar Observations

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on board the Terra and Aqua spacecrafts were launched on December 18, 1999, and May 4, 2002, respectively. One of the features of the MODIS instruments is the ability to perform observations of the lunar surface from its space view (SV) port. This event is scheduled approximately once a month via a spacecraft roll maneuver, which enables the lunar phase to be confined to within 1° for each instrument. The Moon is considered to be an extremely stable reference to monitor the long-term radiometric stability of the reflective solar bands (RSB). Each MODIS instrument can also view the Moon for about four months in a year without a roll maneuver. This is caused by the intrusion of the Moon in the SV. The lunar phase angles of these unscheduled lunar observations are distributed over a wide range varying from approximately 50° to 80° for Terra MODIS and from about -80° to -50° for Aqua MODIS, where the positive phase angle refers to a waning Moon, while the negative phase angle corresponds to a waxing Moon. Together, the scheduled and unscheduled lunar observations are used to monitor the long-term radiometric stability of the RSB. Of the several challenges involved in the modeling of the lunar optical properties, such as its absolute brightness, a number of optical and view geometry effects need to be considered. These effects are much easier to characterize for the scheduled observations due to confinement of the lunar phase angles compared to those for the unscheduled intrusions of the Moon in the SV. Nevertheless, it is still a challenge to remove the view geometry effect in the calibration coefficients derived from the scheduled lunar observations and even more challenging for the unscheduled lunar intrusions. In this work, the lunar absolute irradiance is modeled using known attributes and from the lunar observations by the two MODIS instruments from the time period between the years 2005 and 2012. The model developed here attempts to mitigate for the deficiencies in the lunar irradiance measurements by the RObotic Lunar Observatory (ROLO) model, developed by the United States Geological Survey. Overall, the relative uncertainty of the ROLO model for MODIS calibration has been assessed to be about 4% for the shortest wavelength (a center wavelength of 412 nm) in the phase angle range mentioned above. With our new established lunar model, the calibration coefficients derived from the lunar observations, especially those from the unscheduled lunar observations, for the RSB of the two MODIS instruments are significantly improved for the entire mission. A good agreement is observed between the calibration coefficients derived from the scheduled and unscheduled lunar observations. Both the absolute uncertainty of the new lunar irradiance model and its relative uncertainty due to view geometry variation are much smaller than those of the current ROLO model which has been widely used for most remote sensors' lunar calibrations. Our newly developed lunar irradiance model can be applied to other remote sensors for their lunar calibrations as well. Finally, the significant improvement in the measurement of the lunar irradiance led to a polarization effect in the Moon response for MODIS to be identified. In this article, the impact of the polarization of the moonlight for the MODIS RSB is quantified. This is extremely vital as polarization effect for remote sensors such as MODIS and the follow-on suite of the Joint Polar Satellite System Visible Infrared Imaging Radiometer Suite has been found to significantly increase the calibration uncertainty, especially at short wavelengths.

Effect of free stream angle on mixing performance of hydrogen multi-jets in supersonic combustion chamber

The fuel mixing process within the combustion chamber is a critical procedure for advance of scramjet engine. In current study, the influence of free stream angle on the fuel mixing process of multi jets was thoroughly investigated. This research attempts to applied computational technique to disclose the structure of multi-fuel jets when the supersonic air stream is not normal to the jet direction. The effect of both positive and negative supersonic free stream on the diffusion and penetration of multi-hydrogen jets is fully described. The attention of this research is the flow structure of the multi jets and their interaction in the presence of different free stream angle. Our results indicate that the positive free stream angle expands the mixing zone in the downstream while the negative angle of free stream limited jet distribution inside the combustor. Our results show that mixing efficiency increase approximately 50% when the angle of free stream augments from +20° to −20°. According to our findings, mixing efficiency surges up to 17% when the jet spaces are increased from 4Dj to 10 Dj.

Molecular dynamics simulations of a stacked $$\uppi $$-conjugated soft material: binding energy and preferential geometry for self-assembly

Understanding intermolecular interactions among supramolecular self-assembled organization and identifying the molecular structure relevant to the self-assembly are crucial for designing materials with desired functionalities. Interactions of aromatic rings in a peptide–perylenediimide conjugate (P-1) are investigated using dispersion-corrected density functional theory. The binding energies of fully optimized dimeric P-1 are calculated to identify the most stable conformation of the dimer. We show that the dispersion correction terms have significant contributions to the total energies of the dimers. The combined results from electronic structure calculations and molecular dynamics simulations demonstrate that the stacked dimer with negative inter-planar angle with clock-wise rotation has stronger binding energy than the dimer with positive inter-planar angle. The excess stability of the dimer with clock-wise rotation is attributed to the intra- and inter-molecular $$\uppi $$ – $$\uppi $$ stacking of the side aromatic rings of the dimer facilitated by formation of less number of hydrogen bonds. The stacked P-1 dimer with negative inter-planar angle and stronger binding energy is identified as the building block of a super structure with left-handed helical arrangements. Our calculations will build the first step towards understanding the molecular origin of the stability of a specific super structure of P-1 over the other, as obtained in the experiment relevant to material science and technology.

Parametric analysis and optimization of a simple wind turbine in high speed railway tunnels

The harvesting of wind energy from the slipstream generated when a train passes through a tunnel is a new way to produce renewable energy. From the perspective of CFD (Computed fluid dynamics), a three-dimensional URANS (unsteady Reynolds-averaged Navier–Stokes) model was used to study the energy harvesting performance of wind turbines with different design parameters inside the tunnel during the entire process of a train passing through a tunnel. A higher value of offset distance of blades could promote the power efficiency of the wind turbine inside the wind tunnel. The maximum power efficiency with regard to overlap distance was found when an overlap distance is 0 m. The turbine with a negative twist angle yielded a better performance than the turbine with a positive twist angle. The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h. Given the tunnel distribution in China, 4.8 × 10 12 J energy will be recovered each day by this way, which is sufficient to supply the emergency power for railway lighting. It can also effectively ease the pressure of daily lighting power in railway tunnels. • Harvesting wind energy from railway tunnels is considered feasible. • DFBI (dynamic fluid body interaction) was used to simulate the response of the turbine. • The power efficiency of turbines with various design parameters was quantitatively evaluated. • The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h.

Integrating topography-modified wind flows into structural and environmental wind engineering applications

Topographical features alter the trajectory of wind on the horizontal and vertical planes by creating yaw and pitch angles of wind. Near mountains, topography-induced pitch and yaw angles are confined to the lower part of the atmospheric boundary layer and have considerable magnitudes, thus they should be taken into consideration in wind engineering applications. In this study, a series of wind tunnel tests and CFD simulations are conducted to investigate how wind flows with pitch and yaw angels affect the wind loading of structures and the wind environment in built-up areas. Wind flows with yaw angles are found to create asymmetric pedestrian-level wind environments with large low-wind areas. These results can be replicated using conventional wind flows with a novel technique called the equivalent wind incidence angle method. Wind flows with small positive pitch angles exaggerate the displacements and wind loadings of structures, while negative pitch angles are advantageous for the aerodynamic performance of structures. The differential structural aerodynamics performances are attributable to differences in downwash and upwash flows, and curvature of the shear layers at the top and bottom of a structure subjected to wind flows with positive and negative pitch angles.

The Coriolis force and the direction of rotation of the blades significantly affect the wake of wind turbines

The aerodynamic interactions of wind turbines within a wind farm cause major energy losses. Yaw control is a promising active strategy to tackle this issue in real time during the operation of the plant. The wake of a wind turbine can be steered away from its downstream counterparts by imposing a yaw angle to its rotor. Studying the impact of intentional yaw misalignment on the performance of wind farms located in the northern hemisphere has revealed that, for columns aligned with the wind direction, positive yaw misalignment can lead to an overall increase in the annual energy production, while negative misalignment reduces it. Note that our emphasis is on the front-row turbine being the only yawed turbine of the column. Two unverified reasons have been proposed for the difference between the impact of positive and negative yaw misalignment: (i) the clockwise rotation of the turbine blades and (ii) the Coriolis effect. This paper investigates these two potential explanations by conducting six large-eddy simulations of flow through a wind farm of ten wind turbines located in the northern hemisphere. Results indicate that the Coriolis force and the direction of rotation of the blades both contribute to the inconsistency between the impact of positive and negative yaws on the net power production. The Coriolis force appears to be more influential. The difference between applying a positive and a negative yaw angle to the front-row turbine was found to be approximately 17%. This difference was reduced to almost 7% when the Coriolis force was relaxed, and to approximately 11% when the turbines were set to rotate counter clockwise. Note that a separate study is required to investigate this concept in the southern hemisphere.

Computational study on the performance improvement of axial-flow pump by inlet guide vanes at part loads

In order to investigate the influence of adjustable inlet guide vanes on the hydraulic performance of axial-flow pump and impeller, the axial-flow pump with different inlet guide vane adjustable angles was simulated based on the RNG k-e turbulent model and Reynolds time-averaged equations. The multivariate non-linear regression prediction model was established about the effect of adjustable inlet guide vane on the hydraulic performance of axial-flow pump based on the numerical simulation. The performance curves of axial-flow pump with different inlet guide vane adjustable angles were obtained by calculation, showing that the performance curve shifts towards larger flow volume in case the guide vanes are turned from positive to negative angle. With the increase of inlet guide vane positive angle, the optimum operating of pump is closer to smaller operating condition, but the hydraulic efficiency of pump is lower. The larger the flow is, the larger the decreasing amplitude of pump efficiency is. With the decreases of inlet guide vane negative angle, the higher hydraulic efficiency of pump increases first then decreases. The inlet guide vane angle affects the axial velocity distribution of the blade trailing edge.

Dynamic characteristics of abrasive grains and machined surface features for variable axis diamond grinding of quartz glass

There is a fine application prospect for multi-axis grinding of hard and brittle materials with diamond ball end tool. The effects of tool inclination angles and grinding modes of multi-axis grinding of quartz glass on the dynamic characteristics of the diamond abrasives, surface topography, surface fragmentation phenomenon, and surface roughness were investigated in this work. Material removal characteristics and surface formation conditions would be significantly affected by the effective cutting speed, material stress characteristics, and movement space path derived from different grinding modes and tool inclination angles. The surface texture direction is mainly determined by feed direction of the cutter and initial cutting moment and geometry feature of the engaged diamond abrasives. The surface fragmentation phenomenon of the formed surface is apparent when the corresponding surface roughness values are relatively larger. The machined surface with significant surface fragmentation phenomenon is mainly produced by materials' brittle fracture modes, such as larger positive lead and smaller negative tilt under conventional grinding and smaller negative lead angles and larger positive tilt angles under down grinding. Ideal surface evenness could be obtained by using lead or tilt 0° for conventional and down grinding. The ground surface with smaller surface roughness could be produced when employing tool postures, such as negative lead or positive tilt under conventional grinding and positive lead or negative tilt under down grinding condition.

Numerical Performance Analysis of a Supersonic Combustor at Mach 8 Flight Off-Design Conditions

A numerical investigation of the performance of a supersonic combustor designed for a flight Mach 8 is presented. Numerical simulations are used to assess the characteristics and operational limits of the combustor at design and off-design conditions. The combustor design point corresponds to the cruise condition at a Mach number of 8 and an altitude of 30 km. Off-design conditions correspond to a Mach number of 8 at 28 km altitude and a Mach number of 6 at 26 km altitude. Each off-design condition was investigated at three different angles of attack: 2, 0, and . For constant flight Mach number and altitude, the variation of the angle of attack showed significant influence on the performance of the combustor, mainly on the ignition length. Flying at a negative angle of attack resulted in intense combustion and reduced ignition length. For the Mach 6 off-design condition, a dual-operation mode (ramjet–scramjet) with regions of subsonic combustion was observed. At such condition, it was possible to extend the operation of the combustor and avoid subsonic combustion regions by varying the angle of attack to a positive value. For a constant flight Mach number and altitude, the variation of the angle of attack showed an interesting mechanism to control combustion.

AN INTEGRATED MODEL TO STUDY THE EFFECTS OF OPERATIONAL PARAMETERS ON THE PERFORMANCE AND POLLUTANT EMISSIONS IN A UTILITY BOILER

A gas fired tangentially boiler was modeled under full load conditions. Furnace was simulated by CFD and then was joint with two mathematical models to calculate heat transfer in the convective section, and metal temperature of waterwall tubes. Effects of changing the combustion excess air (0 to 20%) and burners tilt angle (-30° to +30°) were studied. Results showed that the boiler efficiency is optimum if excess air= 10% and the burners have a negative angle. However, these optimum settings cannot produce a superheated and reheated steam of 538 °C which is desirable. Indeed, a zero or positive tilt angle with 10% excess air, or a negative burner angle with 15% excess air lead to highest efficiency by considering the potential of generating superheated steam of 538 °C. In addition, CO emission in low excess air values growths by increasing the burner tilt angle. NOx emission in low and high excess air ratios is lower at positive burner angles while a moderate excess air (10%) needs a zero tilt angle to minimize NOx emission. Furthermore, a critical fouling thickness was computed, considering boiler's circulation ratio, in which the metal temperature of the waterwall exceeds the short overheating threshold. With a certain thickness of scale layers inside the tubes, a burner tilting equal to 0° or 30° postpones tube rupture. These results could be utilized by operating engineers to keep their utility boilers in the most efficient state and avoiding overheating and tube rupture.

Characterizing tilt effects on wind plants

Tilting the nacelle of a wind turbine modifies entrainment into the wind plant and impacts total efficiency. Wakes are deflected vertically by tilt and in the case of large angles can disrupt entertainment from the undisturbed flow or dissipate on the ground. The effect of nacelle tilt on wake behavior is investigated in a series of wind tunnel experiments for the first time. Scale model turbines with a hub height and a diameter of 12 cm are arranged in a Cartesian array composed of four rows of three turbines each. The tilt angle was varied in the third turbine row from −15° to 15° in chosen 5° increments. Stereo particle image velocimetry measurements of the instantaneous velocity field were recorded at four locations for each angle. Tilted wakes are described in terms of the average streamwise velocity, vertical velocity, and Reynolds stresses. Mean kinetic energy quantities are presented, and conditional sampling is employed to quantify the importance of sweep to ejection events in vertical momentum transfer. Additionally, the effect of nacelle tilt on net power production is presented and compared to existing models. Numerical simulations accurately predict losses in net efficiency for positive angles but diverge for negative tilt angles. The results demonstrate that the tilt angle influences wake magnitude, displacement, and recovery. Positive angles deflect wakes above the wind plant, while negative angles encourage entrainment into the wind plant and exhibit rapid recovery.

Effect of windshields on the aerodynamic performance of a four-box bridge deck

A new type of bridge deck section consisting of four-box decks, two side decks for vehicular traffic lanes and two middle decks for railway traffic, has been experimentally investigated for determining its aerodynamic properties. The eight flutter derivatives were determined by the Iterative Least Squares (ILS) method for this new type of four-box deck model, with two windshields of 30 mm and 50 mm height respectively. Wind tunnel experiments were performed for angles of attack α=±6°, ±4°, ±2° and 0° and Re numbers of 4.85x105 to 6.06x105 and it was found that the four-box deck with the 50 mm windshields had a better aerodynamic performance. Also, the results showed that the installation of the windshields reduced the values of the lift coefficient CL for the negative angles attack in the range of -6° to 0°, but the drag coefficient CD increased in the positive angle of attack range. However, galloping instability was not encountered for the tested reduced wind speeds, of up to 9.8. The aerodynamic force coefficients and the flutter derivatives for the four-box deck model were consistent with the results reported for the Messina triple-box bridge deck, but were different from those reported for the twin-box bridge decks.