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Weimin Ding - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Air Profiles Impeded by Plant Canopies for a Variable-Rate Air-Assisted Sprayer
Transactions of the ASABE, 2014Co-Authors: Heping Zhu, Weimin Ding, Xiaochan WangAbstract:Abstract. The preferential design for variable-rate orchard and nursery sprayers requires that the sprayers are able to control the liquid and air flow rates based on the canopy structure in real time. Demand for this advanced feature has increased rapidly with the public demand for reductions in pesticide use. A variable-rate, air-assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the capability of varying the airflow rate by changing the Fan Inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various locations inside tree canopies of three different sizes and foliage densities. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameter with an airflow regulator and measured with a constant-temperature anemometer coupled with hot-wire probes. Peak air velocity and airflow pressure decreased with foliage density and canopy depth. For the 0.34 m Fan Inlet diameter, the airflow pressure ratio of the front portion to the back portion of the canopies was 2.45 for a 1.65 m tall and 13.4 leaf area index (LAI) Tsuga canadensis (Tree 1), 1.43 for a 2.35 m tall and 2.5 LAI Ficus benjamina (Tree 2), and 1.64 for a 3.0 m tall and 1.5 LAI Acer rubrum (Tree 3). Similarly, the front-to-back peak air velocity ratios were 8.55, 1.59, and 1.89 for Tree 1, Tree 2, and Tree 3, respectively. Variations were significant for peak air velocities and airflow pressures among the three different tree volumes and foliage densities. Increasing the Fan Inlet diameter from 0.13 to 0.34 m increased average airflow pressure from 2.84 to 4.01 kg m -2 , from 3.88 to 5.82 kg m -2 , and from 2.46 to 3.75 kg m -2 inside the canopies of Tree 1, Tree 2, and Tree 3, respectively, while it also increased average peak air velocity from 2.6 to 4.5 m s -1 , from 5.5 to 9.1 m s -1 , and from 3.0 to 5.2 m s -1 inside the three tree canopies. Therefore, the new sprayer design with an airflow regulator to alter the Fan Inlet diameter was able to provide variable airflow for different canopy sizes and foliage densities and offered a potentially effective approach to discharge uniform airflow profiles to carry droplets with efficient spray penetration into plant canopies.
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Air velocity distributions inside tree canopies from a variable-rate air-assisted sprayer
2013 ASABE Annual International Meeting, 2013Co-Authors: Heping Zhu, Weimin DingAbstract:Abstract. A variable-rate, air assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the variable air rate capability by changing the Fan Inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various locations inside canopies of three different tree sizes and foliage densities. Tree heights were 1.65, 2.35 and 3.0 m, and leaf area indexes were 13.4, 2.5, and 1.5, respectively. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameters and measured with a constant temperature anemometer coupled with hot-wire sensors. Peak air velocity and airflow pressure decreased as the foliage density and canopy depth increased. For the 0.34 m Fan Inlet diameter, airflow pressure ratio of front portion to back portion of the canopies was 2.45, 1.43 and 1.64 for Tsuga canadensis, Ficus benjamina and Acer rubrum, respectively. Similarly, the front to back peak air velocity ratio was 8.55, 1.59, and 1.89 times for T. canadensis, F. benjamina and A. rubrum, respectively. Variations were significant for peak air velocities and airflow pressures among the three different tree volumes and foliage densities. Increased Fan Inlet diameters from 0.13 to 0.34 m, increased average airflow pressure from 2.84 to 4.01, 3.88 to 5.82 kg/m2, and 2.46 to 3.75 kg/m2 inside canopies of T. canadensis, F. benjamina and A. rubrum , respectively. Therefore, alterations of Fan Inlet diameters for the five-port air assisted sprayer achieved variable air flow rates for different canopy sizes and foliage densities.
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Air Velocity Distributions from Air-assisted Five-port Sprayer
2012 Dallas Texas July 29 - August 1 2012, 2012Co-Authors: Heping Zhu, Weimin DingAbstract:Capability to control both liquid and air flow rates based on tree structures would be one of the advantages of future variable-rate orchard and nursery sprayers. Air jet velocity distributions from an air assisted, five-port sprayer which was under the development to achieve variable-rate functions were measured at various heights above the ground and various distances from nozzle outlets. The air jet velocity was controlled by changing the sprayer Fan Inlet diameter. Air jet initial region length, transition length and expansion angle from five-port nozzles were calculated with an air jet model. The interaction point between adjacent air jets from the five-port nozzles was also determined from the air jet expansion angle. Air velocities at the sprayer travel speed ranging from 0 to 8.0 km/h were measured with a constant temperature anemometer system coupled with hot-film sensors. Air jets expanded at 50° angle and interacted at 0.027 from the nozzle outlets. When the sprayer travel speed was 0 km/h, the axial air velocity increased as the Fan Inlet diameter increased while it decreased in the hyperbola function with the increase of distance from the nozzle outlets. When the sprayer was on the move, due to the air entrainment and air jet diversity, the peak air velocity decreased with the increase of distance from nozzle outlets. The peak air velocity also increased slightly as the Fan Inlet diameter increased but the increase scale was not as great as the increase scale of the Fan Inlet diameter. There were little variations in the peak air velocity with the travel speed and measurement height, confirming the sprayer was able to discharge uniform air profiles to achieve variable air flow rates by controlling the Fan Inlet diameter.
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Unimpeded Air Velocity Profiles of an Air-Assisted Five-Port Sprayer
Transactions of the ASABE, 2012Co-Authors: Heping Zhu, Weimin DingAbstract:A capability that relies on tree structure information to control the flow rates of liquid and air is the preferential design in the development of variable-rate orchard and nursery sprayers. Unimpeded air jet velocities from an air-assisted, five-port sprayer in an open field were measured at four heights above ground, seven distances up to 3 m from the sprayer outlets, and five sprayer travel speeds from 0 to 8.0 km h-1. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameter. Calculations of the air jet initial region length, transition length, and expansion angle from the five-port nozzles were computed with an air jet distribution model. The intersection between adjacent air jets from the five-port nozzles was determined from the air jet expansion angle. Air velocities were measured with a constant-temperature anemometer system coupled with hot-wire sensors. The air jets expanded at a 50° angle and intersected with adjacent air jets at 0.027 m from the five-port nozzles. When the sprayer was stationary (0 km h-1), axial air velocities from the nozzle outlets increased as Fan Inlet diameter increased and decreased as a hyperbolic function as the distance increased. Variations in the peak air velocities and airflow pressures with travel speeds of 3.2 to 8.0 km h-1 and heights of 0.2 to 2.0 m were statistically insignificant. When the sprayer was in motion and due to air entrainment and air jet disturbance, the peak air velocities decreased and airflow pressures increased as distance from the nozzle outlets increased. For all parameters tested, the peak air velocities and airflow pressure increased as Fan Inlet diameter increased, demonstrating that changing the Fan Inlet diameter achieved variable airflow rates with uniform air profiles.
Heping Zhu - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Air Profiles Impeded by Plant Canopies for a Variable-Rate Air-Assisted Sprayer
Transactions of the ASABE, 2014Co-Authors: Heping Zhu, Weimin Ding, Xiaochan WangAbstract:Abstract. The preferential design for variable-rate orchard and nursery sprayers requires that the sprayers are able to control the liquid and air flow rates based on the canopy structure in real time. Demand for this advanced feature has increased rapidly with the public demand for reductions in pesticide use. A variable-rate, air-assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the capability of varying the airflow rate by changing the Fan Inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various locations inside tree canopies of three different sizes and foliage densities. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameter with an airflow regulator and measured with a constant-temperature anemometer coupled with hot-wire probes. Peak air velocity and airflow pressure decreased with foliage density and canopy depth. For the 0.34 m Fan Inlet diameter, the airflow pressure ratio of the front portion to the back portion of the canopies was 2.45 for a 1.65 m tall and 13.4 leaf area index (LAI) Tsuga canadensis (Tree 1), 1.43 for a 2.35 m tall and 2.5 LAI Ficus benjamina (Tree 2), and 1.64 for a 3.0 m tall and 1.5 LAI Acer rubrum (Tree 3). Similarly, the front-to-back peak air velocity ratios were 8.55, 1.59, and 1.89 for Tree 1, Tree 2, and Tree 3, respectively. Variations were significant for peak air velocities and airflow pressures among the three different tree volumes and foliage densities. Increasing the Fan Inlet diameter from 0.13 to 0.34 m increased average airflow pressure from 2.84 to 4.01 kg m -2 , from 3.88 to 5.82 kg m -2 , and from 2.46 to 3.75 kg m -2 inside the canopies of Tree 1, Tree 2, and Tree 3, respectively, while it also increased average peak air velocity from 2.6 to 4.5 m s -1 , from 5.5 to 9.1 m s -1 , and from 3.0 to 5.2 m s -1 inside the three tree canopies. Therefore, the new sprayer design with an airflow regulator to alter the Fan Inlet diameter was able to provide variable airflow for different canopy sizes and foliage densities and offered a potentially effective approach to discharge uniform airflow profiles to carry droplets with efficient spray penetration into plant canopies.
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Air velocity distributions inside tree canopies from a variable-rate air-assisted sprayer
2013 ASABE Annual International Meeting, 2013Co-Authors: Heping Zhu, Weimin DingAbstract:Abstract. A variable-rate, air assisted, five-port sprayer had been in development to achieve variable discharge rates of both liquid and air. To verify the variable air rate capability by changing the Fan Inlet diameter of the sprayer, air jet velocities impeded by plant canopies were measured at various locations inside canopies of three different tree sizes and foliage densities. Tree heights were 1.65, 2.35 and 3.0 m, and leaf area indexes were 13.4, 2.5, and 1.5, respectively. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameters and measured with a constant temperature anemometer coupled with hot-wire sensors. Peak air velocity and airflow pressure decreased as the foliage density and canopy depth increased. For the 0.34 m Fan Inlet diameter, airflow pressure ratio of front portion to back portion of the canopies was 2.45, 1.43 and 1.64 for Tsuga canadensis, Ficus benjamina and Acer rubrum, respectively. Similarly, the front to back peak air velocity ratio was 8.55, 1.59, and 1.89 times for T. canadensis, F. benjamina and A. rubrum, respectively. Variations were significant for peak air velocities and airflow pressures among the three different tree volumes and foliage densities. Increased Fan Inlet diameters from 0.13 to 0.34 m, increased average airflow pressure from 2.84 to 4.01, 3.88 to 5.82 kg/m2, and 2.46 to 3.75 kg/m2 inside canopies of T. canadensis, F. benjamina and A. rubrum , respectively. Therefore, alterations of Fan Inlet diameters for the five-port air assisted sprayer achieved variable air flow rates for different canopy sizes and foliage densities.
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Air Velocity Distributions from Air-assisted Five-port Sprayer
2012 Dallas Texas July 29 - August 1 2012, 2012Co-Authors: Heping Zhu, Weimin DingAbstract:Capability to control both liquid and air flow rates based on tree structures would be one of the advantages of future variable-rate orchard and nursery sprayers. Air jet velocity distributions from an air assisted, five-port sprayer which was under the development to achieve variable-rate functions were measured at various heights above the ground and various distances from nozzle outlets. The air jet velocity was controlled by changing the sprayer Fan Inlet diameter. Air jet initial region length, transition length and expansion angle from five-port nozzles were calculated with an air jet model. The interaction point between adjacent air jets from the five-port nozzles was also determined from the air jet expansion angle. Air velocities at the sprayer travel speed ranging from 0 to 8.0 km/h were measured with a constant temperature anemometer system coupled with hot-film sensors. Air jets expanded at 50° angle and interacted at 0.027 from the nozzle outlets. When the sprayer travel speed was 0 km/h, the axial air velocity increased as the Fan Inlet diameter increased while it decreased in the hyperbola function with the increase of distance from the nozzle outlets. When the sprayer was on the move, due to the air entrainment and air jet diversity, the peak air velocity decreased with the increase of distance from nozzle outlets. The peak air velocity also increased slightly as the Fan Inlet diameter increased but the increase scale was not as great as the increase scale of the Fan Inlet diameter. There were little variations in the peak air velocity with the travel speed and measurement height, confirming the sprayer was able to discharge uniform air profiles to achieve variable air flow rates by controlling the Fan Inlet diameter.
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Unimpeded Air Velocity Profiles of an Air-Assisted Five-Port Sprayer
Transactions of the ASABE, 2012Co-Authors: Heping Zhu, Weimin DingAbstract:A capability that relies on tree structure information to control the flow rates of liquid and air is the preferential design in the development of variable-rate orchard and nursery sprayers. Unimpeded air jet velocities from an air-assisted, five-port sprayer in an open field were measured at four heights above ground, seven distances up to 3 m from the sprayer outlets, and five sprayer travel speeds from 0 to 8.0 km h-1. Air jet velocities were adjusted by changing the sprayer Fan Inlet diameter. Calculations of the air jet initial region length, transition length, and expansion angle from the five-port nozzles were computed with an air jet distribution model. The intersection between adjacent air jets from the five-port nozzles was determined from the air jet expansion angle. Air velocities were measured with a constant-temperature anemometer system coupled with hot-wire sensors. The air jets expanded at a 50° angle and intersected with adjacent air jets at 0.027 m from the five-port nozzles. When the sprayer was stationary (0 km h-1), axial air velocities from the nozzle outlets increased as Fan Inlet diameter increased and decreased as a hyperbolic function as the distance increased. Variations in the peak air velocities and airflow pressures with travel speeds of 3.2 to 8.0 km h-1 and heights of 0.2 to 2.0 m were statistically insignificant. When the sprayer was in motion and due to air entrainment and air jet disturbance, the peak air velocities decreased and airflow pressures increased as distance from the nozzle outlets increased. For all parameters tested, the peak air velocities and airflow pressure increased as Fan Inlet diameter increased, demonstrating that changing the Fan Inlet diameter achieved variable airflow rates with uniform air profiles.
Detlev G. Kröger - One of the best experts on this subject based on the ideXlab platform.
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Contributors to increased Fan Inlet temperature at an air-cooled steam condenser
Applied Thermal Engineering, 2013Co-Authors: Michael Owen, Detlev G. KrögerAbstract:Abstract Current plant operating standards see the cooling performance of an air-cooled condenser (ACC) being calculated based on a reference air temperature measured near ground level (typically at z = 1.2 m). An increase in Fan Inlet temperatures above this reference temperature will result in a decrease in the ACC performance below its design value, and a subsequent reduction in turbine performance. Localised Fan Inlet temperature increases have traditionally been attributed to the presence of plume recirculation. A comparison of test data collected at an existing ACC and numerical data generated in a CFD analysis of the flow around the same ACC shows a discrepancy in the predicted effects of wind on Fan Inlet temperature. Careful analysis of the test data indicates the potential involvement of atmospheric temperature distributions in Fan Inlet temperature deviations. A numerical case study is conducted considering four differing atmospheric temperature distributions. It is found that such distributions, and atmospheric temperature inversions in particular, can cause measurable deviations of the Fan Inlet temperature from the z = 1.2 m reference value; and subsequently measurable deviations in plant behaviour from design. Selecting Fan platform height as the reference elevation is shown to result in a better prediction of actual ACC performance for all atmospheric temperature distributions and wind conditions.
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Flow distortions at the Fan Inlet of forced-draught air-cooled heat exchangers
Applied Thermal Engineering, 1996Co-Authors: K. Duvenhage, Chris J. Meyer, J.a. Vermeulen, Detlev G. KrögerAbstract:The effect of Inlet flow distortions on Fan performance in forced-draught air-cooled heat exchangers (ACHEs) is investigated numerically and experimentally. By varying the distance between the ACHE Fan platform and the ground level, significant changes in air volume flow rate are observed. Three different Fan Inlet shrouds are considered and recommendations towards designing and evaluating the performance of an ACHE are made. The effect of different lengths of a cylindrical Fan Inlet shroud, as well as the effect of cylindrical sections as part of a conical and a bell-mouth Inlet shroud, is also investigated. The results show that a critical length for both the cylindrical Inlet shroud and the cylindrical sections of the conical and bell-mouth Inlet shrouds can be obtained for optimal Fan performance.
Bill Schuster - One of the best experts on this subject based on the ideXlab platform.
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A Comparison of Fan Inlet Dynamic Wall Pressure Measurements from Rig and Engine Tests
18th AIAA CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference), 2012Co-Authors: Taylor R. Marotta, Bill SchusterAbstract:Acoustic measurements are often collected in scaled Fan rig facilities to provide preliminary noise estimates, evaluate hardware configuration changes, and guide design modifications prior to fabricating full-scale engine hardware. As a result, it is important to have some confidence in how the sound pressure levels, frequency spectra, and modal content measured on a Fan rig compare to those measured on a full scale engine. This paper provides comparisons of sub-scale and full-scale dynamic wall pressure measurements for a Fan designed for a business jet class propulsion engine. The comparisons demonstrate that scaled rig testing provides a good estimate of the tone and broadband noise levels of the fullscale Fan. Another feature of interest is that the rig and full-scale Fan noise spectra that are acquired without a turbulence control screen are found to exhibit a broadband skirt around the Fan blade passing tone.
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Noise from a TurboFan Engine Without a Fan from the Engine Validation of Noise and Emission Reduction Technology (EVNERT) Program
14th AIAA CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference), 2008Co-Authors: Charles M. Royalty, Bill SchusterAbstract:ar-field noise levels of a turboFan engine are composed of many noise sources including the Fan Inlet, Fan discharge, compressor stages, combustor, turbine stages, air valves, and external jet. A turboFan engine was run with and without the Fan in order to quantitatively determine the Fan’s contribution to both forward- and aft-radiated noise. The shaft load from the Fan was replaced by a water brake when running without the Fan. Instrumentation internal to the combustor was added to determine its modal structure and help identify any combustor tones in the far-field data. The data was then compared to predictions using industry-standard routines.
Ronald A. Perez - One of the best experts on this subject based on the ideXlab platform.
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Unsteady Pressure Field Investigation of an Axial Fan—Inlet and Outlet Unsteady Pressure Field Measurement
International Journal of Rotating Machinery, 2002Co-Authors: R. S. Amano, Ronald A. PerezAbstract:The unsteady pressure characteristics at Inlet and outlet of an axial Fan were measured in this study. A 1.829 m (6 ft) diameter axial Fan was operated at 1770 rpm in a laboratory. The unsteady pressure field was obtained at three axial positions each with seven radial locations. The results showed that there was a relatively long response time for pressure drop both in the Inlet and outlet during Fan start-up. The measurements also showed that, due to the vortex shedding from the trailing edge of each Fan blade, the Fan outlet pressure oscillation frequency was related to the Fan operating frequency. A theoretical analysis was also conducted in order to understand the measurements. The unsteady pressure measurements helped improve the Fan performance and contributed to the understanding of the vibrational behavior of the Fan unit. The complete set of the measurements obtained can be used as a database for computational fluid dynamics (CFD) codes validation and modeling.
