Academic literature on the topic 'Downforce'
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Journal articles on the topic "Downforce"
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McAllister, Jeffrey, Calliandra Stuffle, Yasa Sampurno, Dale Hetherington, Jon Sierra Suarez, Leonard Borucki, and Ara Philipossian. "Effect of Conditioner Type and Downforce, and Pad Surface Micro-Texture on SiO2 Chemical Mechanical Planarization Performance." Micromachines 10, no. 4 (April 18, 2019): 258. http://dx.doi.org/10.3390/mi10040258.
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Based on a previous work where we investigated the effect of conditioner type and downforce on the evolution of pad surface micro-texture during break-in, we have chosen certain break-in conditions to carry out subsequent blanket SiO2 wafer polishing studies. Two different conditioner discs were used in conjunction with up to two different conditioning downforces. For each disc-downforce combination, mini-marathons were run using SiO2 wafers. Prior to polishing, each pad was broken-in for 30 min with one of the conditioner-downforce combinations. The goal of this study was to polish wafers after this break-in to see how the polishing process behaved immediately after break-in. One of the discs used in this study produced similar micro-texture results at both downforces, which echoed the results seen in the mini-marathon. When comparing the different polishing results obtained from breaking-in the pad with the different discs used in this study, the coefficient of friction (COF) and SiO2 removal rate (RR) were uncorrelated in all cases. However, the use of different discs resulted in different COF and RR trends. The uncorrelated COF and RR, as well as the differing trends, were explained by pad micro-texture results (i.e. the differing amount of fractured, poorly supported pad asperity summits).
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Cross, A., and S. Gough. "Monitoring Downforce." Strain 36, no. 2 (May 2000): 49–50. http://dx.doi.org/10.1111/j.1475-1305.2000.tb01172.x.
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Virk, Simerjeet, Wesley Porter, John Snider, Glen Rains, Changying Li, and Yangxuan Liu. "Cotton Emergence and Yield Response to Planter Depth and Downforce Settings in Different Soil Moisture Conditions." AgriEngineering 3, no. 2 (May 28, 2021): 323–38. http://dx.doi.org/10.3390/agriengineering3020022.
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US cotton producers are motivated to optimize planter performance to ensure timely and uniform stand establishment early in the season, especially when planting in sub-optimal field conditions. Field studies were conducted in 2017, 2018 and 2019 to evaluate the effect of seeding depth and planter downforce on crop emergence and yield in cotton planted in different soil moisture conditions. Field conditions representative of dry, normal and wet soil moisture conditions were attained by applying 0, 1.27 and 2.54 cm of irrigation within the same field. Two cotton cultivars (representing a small-seeded and a large-seeded cultivar, 9259–10,582 and 11,244–14,330 seeds kg−1, respectively), were planted at seeding depths of 1.3, 2.5 and 3.8 cm with each seeding depth paired with three different planter downforces of 0, 445 and 890 N in each block. Cotton was planted in plots that measured 3.66 m (four-rows) wide by 10.67 m long. Results indicated that crop emergence was affected by the seeding depth across most field conditions and higher crop emergence was observed in the large-seeded cultivar at 1.3 and 3.8 cm seeding depths in dry and wet field conditions, respectively. Lint yield was also higher for the large-seeded cultivar at the 3.8 cm seeding depth across all field conditions in 2017, and in dry field conditions in 2018. Planter downforce effect on crop emergence varied among the cultivars where the large-seeded cultivar exhibited higher crop emergence than the small-seeded cultivar at 445 and 890 N downforce. Planter downforce of 445 N yielded greater than the 0 and 890 N treatment in dry field conditions in 2017. The study results suggest that matching planter depth and downforce settings for prevalent soil moisture conditions at planting along with appropriate cultivar selection can help in achieving optimal emergence and yield in cotton.
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Virk, Simerjeet S., Wesley M. Porter, John L. Snider, Jared R. Whitaker, Glen C. Rains, and Changying C. Li. "Influence of Seeding Rate, Planter Downforce and Cultivar on Crop Emergence and Yield in Singulated and Hill-Dropped Cotton." Journal of Cotton Science 24, no. 3 (2020): 137–47. http://dx.doi.org/10.56454/wrjs4850.
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Cotton (Gossypium hirsutum L.) growers are motivated to reduce seeding rates due to increased technology fees associated with improved transgenic cotton cultivars. Advances in planting machinery have improved precision of seed metering and seed placement in recent years. A two-year study was conducted to evaluate the effect of seeding rate, planter downforce, and cultivar on crop emergence and lint yield in cotton planted as singulated and hill-drop (two seed hill-1) configuration. Study treatments consisted of two seeding rates (71,660 and 107,490 seed ha-1), two to three planter downforces (0, 445 and 890 N in 2017; 0 and 890 N in 2018) and two cotton cultivars (representing a large-seeded and small-seeded cultivar, 9,259 - 10,582 and 11,244 - 14,330 seed kg-1, respectively) arranged in a strip-split plot design in both seeding configurations. Crop emergence and lint yield in the middle two rows (four-row plots) were measured to evaluate treatment effects among seeding configurations. Results showed that seeding rate and cultivar did not affect (p>0.05) crop emergence and lint yield in both singulated and hill-drop cotton. Crop emergence varied between the two years due to differences in field tillage conditions. Planter downforce affected crop emergence in singulated cotton but not in hill-drop cotton during both years. Field tillage conditions also influenced downforce effect on crop emergence. Selection of an optimal planter downforce had more significant effect (p<0.05) on singulated cotton than hill-dropped cotton. Results showed that large-seeded cultivars can be utilized to attain a high crop emergence early in the season which can help in minimizing production risks associated with poor stand establishment. High seed and technology fees incurred by growers can be effectively reduced by planting lower seeding rates - given an adequate stand establishment is attained using appropriate planter setup including downforce and cultivar selection.
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Poncet, Aurelie M., John P. Fulton, Timothy P. McDonald, Thorsten Knappenberger, Joey N. Shaw, and Rees W. Bridges. "Effect of Heterogeneous Field Conditions on Corn Seeding Depth Accuracy and Uniformity." Applied Engineering in Agriculture 34, no. 5 (2018): 819–30. http://dx.doi.org/10.13031/aea.12238.
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Abstract. Optimization of planter performance such as uniform seeding depth is required to maximize crop yield potential. Typically, seeding depth is manually adjusted prior to planting by selecting a row-unit depth and a row-unit downforce to ensure proper seed-soil contact. Once set, row-unit depth and downforce are usually not adjusted again for a field although soil conditions may vary. Optimization of planter performance requires automated adjustments of planter settings to varying soil conditions, but development of precision technologies with such capabilities requires a better understanding of soil-planter interactions. The objective of this study was to evaluate seeding depth response to varying soil conditions between and within fields and to discuss implications for development and implementation of active planting technologies. A 6-row John Deere MaxEmerge Plus planter equipped with heavy-duty downforce springs was used to plant corn ( L.) in central Alabama during the 2014 and 2015 growing seasons. Three depths (4.4, 7.0, and 9.5 cm) and three downforces (corresponding to an additional row-unit weight of 0.0, 1.1, and 1.8 kN) were selected to represent common practices. Depth and downforce were not readjusted between fields and growing seasons. Seeding depth was measured after emergence. Corn seeding depth significantly varied with heterogeneous soil conditions between and within fields and the planter failed to achieve uniform seeding depth across a field. Differences in corn seeding depth between fields and growing seasons were as high as 2.1 cm for a given depth and downforce combination. Corn seeding depth significantly co-varied with field elevation but not with volumetric soil water content. Seeding depth varied with elevation at a rate ranging from -0.1 cm/m to -0.6 cm/m. Seeding depth co-variation to field elevation account for some but not all site-specific seeding depth variability identified within each field trial. These findings provide a better understanding of site-specific seeding depth variability and issues to address for the development of site-specific planting technologies to control seeding depth accuracy and improve uniformity. Keywords: Depth control, Downforce, Planter, Precision agriculture, Seeding depth, Uniformity.
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Strasser, Ryan, Sylvester A. Badua, Ajay Sharda, and Matthias Rothmund. "Development of a Test Stand to Quantify the Response of a Planter’s Automatic Downforce Control System." Transactions of the ASABE 64, no. 5 (2021): 1533–43. http://dx.doi.org/10.13031/trans.14047.
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HighlightsThe developed downforce test stand simulated varying disc loads based on actual field data.The planter’s downforce control system was able to maintain the target gauge wheel load 94% of the time.The planter’s downforce control system managed disc load variations of up to 667 N within 1.3 s.Abstract. In recent years, precision planters have incorporated automatic control of the row unit downforce to reduce sidewall soil compaction, maintain proper seeding depth, and control row unit ride quality. By applying an appropriate row unit downforce, more uniform emergence and increased yield can be obtained. However, little research exists on evaluating the response and accuracy of downforce control systems during planting. Therefore, the objectives of this study were to (1) develop a laboratory-scale row unit downforce test stand and (2) use the test stand to evaluate the downforce control system response time and the load distribution between the gauge wheels, opening discs, and closing wheels using simulation scenarios based on real-world soil and terrain data. The downforce test stand was able to distribute the applied downforce to the row unit gauge wheels, opening discs, and closing wheels. It was also capable of varying the row unit ride height. The simulation scenarios using the test stand showed that the downforce control system maintained the target gauge wheel load (GWL) of 379 N within ±223 N for more than 94% of the time during all simulations. The downforce control system was also able to manage the GWL within 1.3 s for disc load variations up to 667 N. Keywords: Automatic downforce control, Downforce test stand, Gauge wheel load, Simulation.
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Konwar Roy, Sidhant, and Abhishek Mahesh Sharma. "Effects of Aerodynamic downforce on Vehicle Control and Stability." Journal of University of Shanghai for Science and Technology 23, no. 11 (November 6, 2021): 78–85. http://dx.doi.org/10.51201/jusst/21/10861.
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This paper deals with the analysis of vehicle handling with the variation of downforce. A vehicle with aero package were taken and the values of aerodynamic downforce and front downforce distribution for different front and rear ride heights were taken. This was followed by the generation of yaw moment diagram at original ground clearance of 30mm. Aero map data were collected and individual yaw moment diagrams were collected from which vehicle handling parameters are noted. Different contour plots were made to understand the variation of vehicle handling with different ride heights (aerodynamics downforce and downforce distribution). The paper concludes with the sensitivity study where effects of aerodynamic downforce were recorded on vehicle control and stability.
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Li, Baosheng, Yu Tan, Jian Chen, Xingxing Liu, and Shenghui Yang. "Precise Active Seeding Downforce Control System Based on Fuzzy PID." Mathematical Problems in Engineering 2020 (May 12, 2020): 1–10. http://dx.doi.org/10.1155/2020/5123830.
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Soil compaction is an important procedure of precision seeding operation. In this paper, a precise downforce control system based on fuzzy PID was proposed in order to improve the quality of the soil compaction and the accuracy of setting working parameters. The conventional mechanism of seeders for soil compaction was optimised. The compressing spring of the compaction mechanism was replaced by a linear motor, which is actively controlled to adjust downforce in real time. A force sensor was connected in series with the linear motor to detect the actual downforce from a press wheel acting on soil. The detected downforce was employed as feedback for the fuzzy PID model. A slave real-time control system was constructed by using an STM32 microcontroller. A user interface was designed for the portable master computer system based on the ForLinx embedded platform to facilitate the setting of target downforce and display the actual downforce in real time. Meanwhile, it was able to adjust the system for different operating requirements, such as soil stiffness, moisture, and crop species. Experiments were conducted on a soil bin, and the results indicated that the active control system has better performance than the conventional passive system in downforce control. The downforce was stable with a variance less than 2.6% under different conditions, and it was 8.11% less than the conventional passive system.
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Poncet, Aurelie M., John P. Fulton, Timothy P. McDonald, Thorsten Knappenberger, and Joey N. Shaw. "Corn Emergence and Yield Response to Row-unit Depth and Downforce for Varying Field Conditions." Applied Engineering in Agriculture 35, no. 3 (2019): 399–408. http://dx.doi.org/10.13031/aea.12408.
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Abstract. Optimum row-crop planter seeding depth performance is required to place seeds within proper soil conditions to ensure quick germination and maximize the likelihood of uniform emergence. Seeding depth is adjusted prior to planting by selecting a row-unit depth, followed by the adjustment of a row-unit downforce for proper seed-soil contact. Optimum row-unit depth and downforce settings required to maintain a consistent seeding depth are variable. The objective of this study was to evaluate corn ( L) emergence and yield response to row-unit depth and downforce in changing field conditions between sites and growing seasons. Corn was planted with a 6-row John Deere MaxEmerge Plus planter equipped with heavy duty downforce springs. The experiment was conducted in 2014 and 2015 in Central Alabama for non-irrigated corn. Two fields, three row-unit depths (4.4, 7.0, and 9.5 cm), and three row-unit downforce settings (0.0, 1.1, and 1.8 kN) were evaluated. Emergence was measured at 75 and 100 Growing Degree Days (GDDs). Yield was measured using a yield monitor installed on the combine harvester. Corn emergence was mainly affected by changes in weather conditions. Row-unit depth and downforce did not affect corn emergence in warmer weather conditions but the 4.4 cm row-unit depth resulted in more emergence than the other row-unit depth settings in cooler weather conditions. Yield ranged from 8,000 to 13,000 kg ha-1 across treatments and yield was mostly affected by changing growing conditions between fields and growing seasons. Plant population significantly varied with treatments, but lower plant populations did not always result in lower corn yields. These findings provided a better understanding of corn emergence and yield response to row-unit depth and downforce in varying field conditions. Keywords: Corn, Depth, Downforce, Emergence, Maize, Planter, Yield.
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Baltagiu, Daniel, Radu Gaiginschi, Radu Drosescu, and Ioan Damian. "A New Electric Drive System for a Disc Brake System Used in the Vehicle, Experimental Stand." Applied Mechanics and Materials 659 (October 2014): 139–44. http://dx.doi.org/10.4028/www.scientific.net/amm.659.139.
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Papers present a new solution for achieving downforce to a brake disc, using a drive gear and ball screw-nut, which the construction adopted, allows moving ball-screw and making the necessary downforce for breaking. The stand includes downforce creating system required by deceleration, and is equipped with a plurality of sensors to determine the following parameters. Measurement of downforce-ring load cell, displacement in the running drive-pressure transducer, mechanism decoupling travel-differential inductive transducer, electrical motor and gear drive mechanism speed-speed transducer, and electric drive motor torque-lamellar load cell. These transducers allow the control of screw ball to realize the forces that are acting on the brake linings in order to control the speed of the vehicle. Using this construction, brake actuation can get higher quality reactions in brake systems.
Dissertations / Theses on the topic "Downforce"
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Strasser, Ryan Scott. "Development of a test stand for the evaluation of row crop planter automatic downforce systems and the evaluation of a row crop planter electronic drive singulation seed meter." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/36243.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Ajay Sharda
In recent years, the technology employed on precision row-crop planters has rapidly advanced. These new technologies include automatic downforce control systems and electronic drive singulation seed meters. These new technologies offer producers higher productivity through high speed planting and increased yield potentials through accurate seed spacing and placement. To begin to understand the benefits and performance of these new technologies, research must be conducted that specifically targets these new systems. With this research, producers would be able to better select equipment for their operation and have a deeper understanding of proper system operation and settings. A test stand, of a scissor-lift type design, was developed to evaluate row crop planter automatic downforce systems. Evaluation of a planter’s automatic downforce system is important for understanding the planter’s capability of maintaining target seeding depth throughout varying field conditions. The test stand consists of a horizontal platform that can raise and lower to simulate terrain changes as well as a mechanism to load the planter row unit’s opening discs to simulate varying soil texture. The vertical height of the test stand and the disc load can be varied in real-time based on utilizing real-world scenarios under simulated conditions to evaluate downforce system response. The stand incorporated several sensors to obtain the overall applied downforce, applied disc load, applied gauge wheel load, and hydraulic pressure. The test stand’s capabilities were evaluated and found to be satisfactory for planter downforce system testing. The test stand was then used to evaluate a commercial automatic downforce system when operating under simulated field conditions. Field data was used to create simulations representing soil type changes, planter operating speed changes, and extreme conditions such as a hard, packed clay or rocky soil type. It was found that the evaluated downforce system was able to maintain target gauge wheel load to within ±223 N for at least 94% of the time during all simulations. This would suggest that the planter would be able to maintain target seeding depth for at least 94% of field operations. Another key aspect for precision agricultural planters is to achieve accurate seed spacing at varying speeds. An electronic drive singulation seed metering system was evaluated to gather the meter’s effectiveness for high speed planting during straight and contour farming mode using simulated field conditions. The simulated conditions were used to gather the meter’s response when encountering high planting speeds, accelerations, decelerations, point-rows, and contours. These meters were found to be highly accurate, with less than 1.5% error in target seed meter speed during all simulated conditions. The meters were also found to have a response time that was always 0.34 seconds or less for all simulated conditions.
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Diasinos, Sammy Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "The aerodynamic interaction of a rotating wheel and a downforce producing wing in ground effect." Awarded by:University of New South Wales. Mechanical & Manufacturing Engineering, 2009. http://handle.unsw.edu.au/1959.4/44516.
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The performance of current open wheeler race cars depends heavily on the effectiveness of the aerodynamic package of which the front wing and wheels make a significant contribution. Previous investigations have focused on the aerodynamic characteristics of each of these bodies in isolation. Investigations that have considered both working in unison have conflictingly reported that the wheel presence aids or hinders the wing???s performance while the wheel???s aerodynamic performance has been neglected. In order to obtain a more thorough understanding of the interaction of a wing and wheel, experimental results were used to validate a computational model used to investigate a wing and wheel in isolation and in combination. The combined wing and wheel investigation demonstrated that three main interactions can occur, depending on the selection of wing span, angle of attack and height used, while the wheel width and track were found to have little influence. The three interacting states differ in the path that the main and secondary wing vortices take around the wheel and the subsequent variation in the combined wake structure. In general, the wing in the presence of the wheel reduced the wing???s ability to generate downforce by up to 45% due to the high pressure regions generated forward of the wheel. This was also found to alleviate the adverse pressure gradients experienced by the wing, and also reduce the drag by up to 70%. For this reason, the downforce loss phenomenon was observed to occur at a height 0.08c to 0.32c lower in comparison to the same wing in isolation, dependant on the wing span. Wheel lift and drag values were also observed to reduce in the presence of a wing by up to 65% and 38% respectively due to the influence of the wing???s flow structures have on the wake of the wheel. As a result,it was shown that the combined wing and wheel downforce and drag optima differed by up to 75% and 25% respectively to those which would be estimated if the two bodies were investigated individually and the results summed highlighting the importance of investigating these two bodies in unison.
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Akanni, Saïf-Deen. "Air jet vortex generator flow control applied to the rear multi element high downforce wing of a Formula One racing car." Thesis, City University London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269298.
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Ehirim, Obinna Hyacinth. "Aerodynamics and performance enhancement of a ground-effect diffuser." Thesis, Cranfield University, 2018. http://dspace.lib.cranfield.ac.uk/handle/1826/13211.
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This study involved experimental and equivalent computational investigations into the automobile-type 3―D flow physics of a diffuser bluff body in ground-effect and novel passive flow-control methods applied to the diffuser flow to enhance the diffuser’s aerodynamic performance. The bluff body used in this study is an Ahmed-like body employed in an inverted position with the slanted section together with the addition of side plates along both sides forming the ramped diffuser section. The first part of the study confirmed reported observations from previous studies that the downforce generated by the diffuser in proximity to a ground plane is influenced by the peak suction at the diffuser inlet and subsequent static pressure-recovery towards the diffuser exit. Also, when the bluff body ride height is gradually reduced from high to low, the diffuser flow as indicated by its force curve and surface flow features undergoes four distinct flow regimes (types A to D). The types A and B regimes are reasonably symmetrical, made up of two low-pressure core longitudinal vortices travelling along both sides of the diffuser length and they increase downforce and drag with reducing ride height. However, below the ride heights of the type B regime, types C and D regimes are asymmetrical because of the breakdown of one vortex; consequently a significant loss in downforce and drag occurs. The second part of the study involved the use ― near the diffuser exit ― of a convex bump on the diffuser ramp surface and an inverted wing between the diffuser side plates as passive flow control devices. The modification of the diffuser geometry with these devices employed individually or in combination, induced a second-stage pressure-drop and recovery near the diffuser exit. This behaviour was due to the radial pressure gradient induced on the diffuser flow by the suction surface ii curvature of the passive devices. As a result of this aerodynamic phenomenon, the diffuser generated across the flow regimes additional downforce, and a marginal increase in drag due to the profile drag induced by the devices.
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Job, Štefan. "Experimentální měření aerodynamických silových účinků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230273.
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This thesis deals with the effect of the aerodynamic forces on a vehicle. It contains the description of the test run of the vehicle, the proposal on how to process the measurements, the processing of the measurements themselves, and the final assessment of the results as to their accuracy and the possibility of repeating the experiment. Furthermore, this thesis contains the comparison of the effect of the individual aerodynamic features on the race car.
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Gagliardi, Andrea. "Studio CFD dell'aerodinamica esterna di una vettura di formula student." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Questo elaborato ha lo scopo di studiare un pacchetto aerodinamico progettato per una vettura di formula student.
È stata fatta una breve introduzione sulla Formula SAE, con una descrizione sintetica delle regole delle varie prove dinamiche e statiche, dopodichè sono stati richiamati i concetti di aerodinamica più importanti per il mondo dell’automotive: strato limite, differenza tra un flusso laminare e un flusso turbolento, distribuzione di velocità attorno ad un corpo in movimento immerso in un fluido.
E' stata, poi, fatta una breve analisi degli aspetti più importanti della dinamica di un veicolo, come l’interazione tra forze aerodinamiche e forze di contatto tra ruote e strada ed il comportamento dinamico di uno pneumatico da competizione.
Il seguito dell’elaborato è incentrato sulla valutazione delle performance aerodinamiche della UBM 18, ultima concezione di UniBo Motorsport, partendo dagli obiettivi progettuali, basati sul miglioramento delle performance del pacchetto aerodinamico della vettura dell’anno precedente, per poi passare alle analisi CFD effettuate durante tutta la fase di progettazione per indirizzare i progettisti nello sviluppo dei vari componenti del pacchetto. Terminata la descrizione della metodologia di preparazione del modello, di discretizzazione, simulazione della vettura e analisi dei risultati, si passa alla vera e propria valutazione delle performance della vettura in una prova di skidpad e di endurance, quest’ultima utilizzando un modello vettura con il software Optimumlap, anche in termini di economia, quindi di aumento dei consumi dovuti all’aumento della resistenza aerodinamica e di aumento del peso finale della vettura.
Il capitolo finale è dedicato all’analisi della telemetria registrata on board durante i test sulla pista di Rioveggio (BO) nei quali si è cercato di validare i risultati CFD.
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Soliman, Paulo Augusto. "Estudo numérico do controle passivo de camada limite via geradores de vórtices em perfil aerodinâmico de um veículo de competição." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180813.
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O presente trabalho apresenta um estudo numérico dos efeitos da aplicação de geometrias geradoras de vórtices, com intuito de controlar passivamente a camada limite, em um perfil aerodinâmico que integra a asa traseira de multi elementos de um veículo de Fórmula SAE. As equações de Navier-Stokes com médias de Reynolds foram resolvidas utilizando o modelo k-ω SST (Shear Stress Transport) para o problema de fechamento da turbulência. Uma metodologia numérica padrão foi definida e utilizada nos diferentes casos analisados. Domínio de cálculo, malha, condições de contorno e critério de convergência foram escolhidos com base em norma SAE para análise numérica de escoamento externo em veículos terrestres. As camadas de volumes prismáticos próximos as superfícies com não-deslizamento foram dimensionadas de forma a resultar em um tratamento de parede adequado ao modelo de turbulência aplicado. O método GCI (Grid Convergence Index) foi utilizado para avaliar a qualidade da malha. Com o intuito de reduzir o custo computacional nos testes com diferentes configurações de geradores de vórtices, apenas parte de interesse do domínio de cálculo foi resolvido, impondo perfis de velocidade, energia cinética da turbulência e dissipação específica em sua entrada. Estas condições foram importadas da simulação com domínio completo resolvida Para verificar a correta captação dos principais efeitos físicos envolvidos, comparações com resultados experimentais foram feitas para 2 casos com escoamentos representativos: o corpo de Ahmed e um perfil aerodinâmico com geradores de vórtices. Além disso, as diferenças entre resolver o domínio completo ou parcial foram estudadas em outro comparativo com resultados experimentais. Concluiu-se que a metodologia numérica foi capaz de obter os coeficientes aerodinâmicos, e suas tendências frente a mudanças de geometria, nos casos estudados. Resolver parcialmente o domínio, impondo perfis em sua entrada, acarretou em diferença nos coeficientes obtidos na ordem de 2% para o coeficiente de sustentação e 7% para o coeficiente de arrasto. O controle passivo via geradores de vórtices foi eficaz em atrasar a separação da camada limite no flap do veículo de Fórmula SAE, as melhoras nos coeficientes de arrasto e sustentação foram da ordem de 7% e 0,3%, respectivamente.The present work is a numerical study of the effects of the application of vortex generating geometries, in order to passively control the boundary layer, in an aerodynamic profile that integrates a multi-element rear wing of a Formula SAE vehicle. The Reynolds Averaged Navier-Stokes equations were solved using the k-ω Shear Stress Transport model for the turbulence closure problem. A standard numerical methodology was defined and used in the different cases analyzed. Computational domain, mesh, boundary conditions and convergence criteria were chosen based on SAE standard for numerical analysis of external flow in land vehicles. The layers of prismatic volumes near the non-slip surfaces were dimensioned to result in a wall treatment suitable to the applied turbulence model. The Grid Convergence Index (GCI) method was applied to evaluate the mesh quality. In order to reduce the computational cost in tests with different vortex generators configurations, only the part of interest of the calculation domain was solved, imposing velocity, turbulent kinetic energy and specific dissipation profiles on its inlet These conditions were imported from the full domain simulation already solved. To verify the correct capture of the main physical effects involved, comparisons with experimental results were made for 2 cases with representative flows: the Ahmed body and an aerodynamic profile with vortex generators. In addition, the differences between solving the complete or partial domain were studied in another comparative with experimental results. It was concluded that the numerical methodology was able to obtain the aerodynamic coefficients, and their tendencies against changes of geometry, in the cases studied. Partially solving the domain, imposing profiles at its entrance, resulted in a difference in the coefficients obtained in the order of 2% for the lift coefficient and 7% for the drag coefficient. The passive control via vortex generators was effective in delaying the separation of the boundary layer on the flap of the Formula SAE vehicle, the improvements in drag and lift coefficients were of the order of 7% and 0,3%, respectively.
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Lind, Jacob. "Fordonsdynamiska effekter av en justerbar multi-element vinge jämfört med en single-element vinge för sportbilar - En teoretisk studie." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42719.
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Sportbilsbranchen har utvecklats i flera decennier och det råder en konstant efterfrågan för nya idéer och teknologier som kan förbättra sportbilar. Detta stämmer framförallt in inom superbilsbranchen, där det är en stor konkurrens mellan företag om vem som först utvecklar nya teknologier som gör deras bilar till de attraktivaste på marknaden. Ett område inom fordonsutvecklingen är aerodynamik och dess användning för att förbättra fordons prestanda vid körning i raksträckor och i kurvor. Sportbilstillverkarnas mål är oftast att utveckla fordon till att accelerera snabbt, nå en hög topphastighet, kort bromssträcka samt att nå så hög hastighet som möjligt i kurvor utan att glida av vägen. Det finns flera metoder för att uppnå detta, men det sätt som behandlas i denna rapport är anvädningen av bakvingar. Bakvingar förekommer i flera konfigurationer och modifikationer för att uppfylla användarens önskemål och krav. De vingkonfigurationer som behandlas i detta projekt är single- och multi-elementa vingar. Single-elementa vingar kännetecknas av att de består av en enkel vingarea. Fördelen med dessa konfigurationer är att de producerar låga luftmotstånd vid låga anfallsvinklar, vilket bland annat gör dem optimala för höga hastigheter. Multi-elementa vingar består av två eller fler vingareor. I och med detta kan en större negativ lyftkraft uppnås vilket gör dem optimala vid svängning. Multi-elementa vingar kan även användas vid högre anfallsvinklar med en minskad risk att turbulens uppstår. Syftet i detta projekt var att ge en teoretisk analys av vad som kan uppnås om en single- och multi-element vinge kombineras i en och samma konfiguration. Tanken är att i praktiken har denna kombinerade vingkonfiguration en klaff som kan fällas ut för att kunna utnyttja båda vingkonfigurationernas fördelar och på så sätt förbättra sportbilars acceleration, topphastighet, bromsningsförmåga samt svängningshastighet. Metoden bestod av att använda teoretiska beräkningar och analyser för att nå slutsatser om en sådan typ av vinge skulle vara fördelaktig, eller om de existerande konfigurationerna är tillräckliga. Detta gjordes genom att använda en tidigare analys som undersökte kraftskillnaderna hos en single- och multi-element vinge med samma dimensioner. Med vingarnas data kunde beräkningar genomföras på ett typfordon, där resultaten av vingarnas påverkan på fordonets topphastighet, acceleration, bromsning och kurvkörning samlades in och jämfördes. Med dessa jämförelser kunde en slutsats dras om vilka vingkonfigurationer som visade bäst resultat vid de olika situationerna. Resultatet visar att en vinge som är en kombination av single- och multi-element kan vara fördelaktig över existerande konfigurationer. I och med att den single-elementa vingen har lägst luftmotstånd så passar den bäst vid acceleration vid hög hastighet samt för att uppnå höga topphastigheter. Vid acceleration i låga farter är den multi-elementa vingen mer fördelaktiga på grund av dess högre negativa lyftkraft. Den multi-elementa vingen passar även bättre för kraftigare bromsningsverkan samt högre svängningshastigheter.The sports car industry has been under constant development for decades and there is a large demand for new ideas and technologies that can improve sports cars. This is particularly true in the super car industry, where there is a constant competition between companies about who first develops new technologies that can make their cars the most attractive on the market. One area of development is in aerodynamics and how it can be used to improve vehicle performance when driving on straights and in curves. Usually, the goal is to get the vehicle to accelerate faster, reach a high top speed, have a short braking distance and to have as high speed as possible in curves without slipping off the road. There are several methods to achieve this, but the way that is discussed in this report are the use of rear wings. Rear wings exist in several configurations in order to reach the requests and requirements of the car manufacturer. The wing configurations addressed in this project are single and multi-element wings. Single-element wings are characterized by their single wing area. The advantage of these configurations is that they produce low resistance at low angles of attack, which among other things makes them optimal for high speeds. Multi-element wings consist of two or more wing areas. With this, a larger negative lifting force can be achieved, which makes them optimal for achieving high turning speeds. Multi-element wings can also be used at higher angles of attack without the risk of the wing stalling. In this project, the goal is to provide a theoretical analysis of what can be achieved if a single and multi-element wing is combined into one and the same configuration. The idea is that in practice, this combined wing has a flap that can be folded in and out in order to be able to utilize the advantages of both wing configurations and thus improve a sports car's acceleration, top speed, braking ability and turning speed. The method consisted of using theoretical calculations and analyses to reach conclusions as to whether such a type of wing would be advantageous, or if the existing configurations are good enough for what they are used for. This was done by using a previous analysis that examined the differences between a single and multi-element wing of the same dimensions. With the data from these wings, calculations could then be made on a theoretical car, where the results of the wings' influence on top speed, acceleration, braking and curve driving were collected and compared. With these comparisons, a conclusion could be made about which of the wings were best for the different scenarios. The result shows that a wing with a combination of single and multi-elements can be advantageous. Since the single-element wing has the lowest drag, it fits best at top speeds. When accelerating at low speeds, multi-element wings are more advantageous because of their higher downforce. They also fit better for greater braking effect and higher turning speeds.
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Ravelli, Umberto. "Aerodynamics of a 2017 Formula 1 Car: Numerical Analysis of a Baseline Vehicle and Design Improvements in Freestream and Wake Flows." Doctoral thesis, Università degli studi di Bergamo, 2019. http://hdl.handle.net/10446/128609.
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In this work an extensive numerical analysis of open-wheeled racing car aerodynamics is presented. The whole CFD workflow, from meshing to calculation, was carried out by the open-source software OpenFOAM®, in the steady RANS framework. After investigating the mechanisms behind ground effect by means of simple test cases, including a diffuser-equipped blunt body and a single element wing, attention was focused on the 2017 Formula 1 car designed by the British constructor ©PERRINN. The validation of the numerical results in terms of drag, downforce, efficiency and front balance was accompanied by a qualitative study of the flow around the car. Axial vorticity plays a key role in the generation of downforce and the use of ground effect improves the efficiency of the overall vehicle. In the second step of the research, it was found that front and rear ride height have a strong influence on the dynamic behaviour of the car. Since racing implies a close interaction with other vehicles, the core of the research was devoted to evaluation and subsequent improvement of aerodynamic performance in wake flows. Tandem-running simulations at different distances between lead and following cars put in evidence that running in slipstream results in a strong worsening of downforce and a dramatic change in front balance.
To overcome these limitations, the baseline vehicle was subjected to a targeted aerodynamic development. Among the tested aero packages, one in particular provided encouraging results: it ensures higher downforce and efficiency than the baseline configuration while fulfilling, at the same time, the goal of reducing the above mentioned performance worsening in slipstream. The concepts behind the effectiveness of the new design deal with a better management of the chaotic flow underneath the car; moreover, underbody and rear wing adjustments contribute to generation of a shorter and narrower wake. Overall, an easier approach to the lead car and a safer overtaking could be achieved through small modifications to 2017 F1 Technical Regulations, without disrupting the current F1 car layout. As a further check of the robustness of the new design proposals, all the developed aerodynamic configurations have been tested in yawed flow. Finally, the last section of the research aimed at quantifying the lap-time performance of the vehicles equipped with the new aero packages, since each track requires specific levels of downforce and efficiency. Results in terms of aerodynamic specifications are in line with those typically encountered in current F1 grand prix races.
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Zeller, Jonathan. "Mobile soil bin development and testing." Thesis, 2018. http://hdl.handle.net/2097/39298.
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Master of ScienceDepartment of Biological & Agricultural Engineering
Daniel Flippo
In 2050 the world’s population is projected to be over 9 billion people, creating a need for more agriculture production than ever before. One way to increase production of crops is to get them planted in an optimum planting window. This allows the crops to take the most advantage of the longer days during the growing season thus increasing their yield. The growing size of farms and reduced amount of farmers puts more pressure on each remaining farmer to mechanize more heavily, and to get more acres planted faster in order to get crops planted in time. Most areas have an optimal planting window of a few weeks. This drives a need for planters to get bigger so one man can plant more acres in a day. Besides getting bigger, planters are also getting able to accurately plant faster. Today many of the new planters are “high speed,” meaning they are able to plant at speeds of 7 to 10 mph. The typical research and discussions of high speed planters tend to focus on the speed effects on the seed placement, emergence, planting rates, active downforce systems, metering systems etc. There is little discussion on the effects these higher planting speeds have on the draft requirements of the row unit itself. There needs to be more knowledge about the relationship between soil and planting tools in order to optimize power and performance of the tools to minimize fuel consumption, labor, and soil compaction. In order to test the draft forces of various tillage and planting tools in different field conditions there needs to be a machine that can repeatedly test multiple tools in multiple field conditions over a wide range of speeds. This paper is about the development of such a machine. The Cultivation Assessment Test Apparatus (CAT App.) is a device used to pull tillage and planting tools at a consistent depth at different speeds measuring the draft and downforce requirements during tests.
Books on the topic "Downforce"
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Competition car downforce: A practical guide. Sparkford, Nr Yeovil, Somerset: G.T. Foulis, 1998.
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Corcoran, Mr David, Mr David Corcoran, and Mr David Gardner. Downforce Guitar : The Easy Way to Play the Guitar: Major and Minor Triads/100 Finger Picking Styles for Downforce Guitar. Createspace Independent Publishing Platform, 2011.
Find full textBook chapters on the topic "Downforce"
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Löfdahl, Lennart. "Evolution of downforce on performance cars." In Proceedings, 1411–26. Wiesbaden: Springer Fachmedien Wiesbaden, 2018. http://dx.doi.org/10.1007/978-3-658-21194-3_110.
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Guo, Zhidong. "Numerical Simulation Study of Drag and Downforce on the Rear Wing of F1 Cars." In Proceedings of the 2022 2nd International Conference on Computer Technology and Media Convergence Design (CTMCD 2022), 632–45. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-046-6_74.
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Solazzi, Luigi, Giuseppe Schinetti, and Riccardo Adamini. "Developed an Innovative Handbike Fork Made of Composite Material." In Studies in Health Technology and Informatics. IOS Press, 2022. http://dx.doi.org/10.3233/shti220861.
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In this research, the design of a new competitive handbike fork, made of a composite material, is presented. The study is based both on an early finite element analysis and on a CFD analysis of the characteristics and performance of a standard fork made of aluminum, allowing to define the loading and the flux conditions and to provide a design optimization of the fork. The model was later implemented iteratively with the properties of a carbon-fiber composite material. The results obtained show that the new model allows a weight and a drag force reduction and a downforce improvement, with a stiffness and a safety coefficient comparable to the standard aluminum fork.
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Sharda, A., R. Strasser, and M. Rothmund. "Development and Utilization of a Planter Automatic Downforce Evaluation Test Stand to quantify System Response and Accuracy." In Land.Technik AgEng 2017, 345–54. VDI Verlag, 2017. http://dx.doi.org/10.51202/9783181023006-345.
Full textConference papers on the topic "Downforce"
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Cooper, Kevin R., J. Syms, and G. Sovran. "Selecting Automotive Diffusers to Maximise Underbody Downforce." In SAE 2000 World Congress. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-0354.
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Katz, Joseph. "Aerodynamic Drag and Downforce of a Competition Motorcycle." In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2022. http://dx.doi.org/10.4271/2022-01-0892.
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Gogel, Douglas, and Hiroshi Sakurai. "The Effects of End Plates on Downforce in Yaw." In Motorsports Engineering Conference & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2006. http://dx.doi.org/10.4271/2006-01-3647.
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Singh, Rajneesh, and Kevin Golsch. "A Downforce Optimization Study for a Racing Car Shape." In SAE 2005 World Congress & Exhibition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2005. http://dx.doi.org/10.4271/2005-01-0545.
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Su, Yuling, and Akshay Basavaraj. "Computational Analysis of Benzing Airfoils for Optimization in a Wing Configuration for a Formula SAE Car." In ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69372.
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Wing selection plays a crucial role for race cars as it generates the most downforce. This is essential to maintain traction which leads to faster lap timings, and maintain efficiency in the performance of the race car. In this paper, the numerical simulation of a Formula SAE (FSAE) Car is performed. The FSAE car is restricted by regulations in terms of the geometry of the front and rear wing configuration. Hence, it becomes necessary to optimize the selection of airfoils in order to get the best out of the wing configuration. It is also essential to observe the tradeoff between the downforce generated and the drag produced in a racecar for optimal performance. This serves as the primary motivation of this research paper. The focus is on Benzing airfoils, which show considerably better performance in terms of downforce production in a race car than conventional airfoils. The wing configuration utilized in this research paper consists of a single mainplane and two flaps.. The freestream velocity of the flow is in the range of 0–60mph (0–26m/s). The 122 series of Benzing airfoils is utilized for the mainplane and the 153 series of Benzing airfoils is utilized for the flaps for manufacturing reasons. Nine different combinations of Benzing airfoils were utilized wherein it was noticed that an appropriate selection of the airfoils for the mainplane and flaps with a fixed angle of attack difference, leads to a 12–15% increase in downforce amongst the Benzing airfoils itself. Similarly, it was also observed that an optimal configuration would lead to a 12–15% decrease in drag in comparison too poor performing airfoil. The Be 153-055 airfoil acts as an excellent flap within the limits of computational error. Data from an on-track test is used in order to verify the approach utilized in this paper in order to validate if the approach used in this paper would be feasible. It is observed that the Benzing airfoil does improve the average cornering speed of the car by around 10% in comparison to the previous configuration of S1223 airfoil as the main plane and the goe 477 airfoil as the flap.
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Epple, Philipp, Manuel Hellmuth, and Stefan Gast. "Ground Effect on Wings for Formula Student Race Cars." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71807.
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Aerodynamic design is getting continuously more important for formula student race cars. One very important aerodynamic device of these cars is the front wing. The front wings, as well as the rear wings generate a downforce to improve the stability of the vehicle especially when driving on curves. The front wings are mounted so close to the ground that they are already in ground effect. The rear wings are already too far from the ground and therefore are not in ground effect. Therefore it is very important to design the front wings in such a way as to maximise the ground effect. Therefore these wings have to be mounted at a proper distance from the ground in order to have the maximum ground effect. If the front wings are too close to the ground the ground effect disappears or even the downforce is less than far from the ground. Since the rear wings are out of the ground effect they have not been considered in this investigation. In this work a series of wing designs, with different aspect ratios, at different angles of attack and at different distances from the ground where designed and investigated with computational fluid dynamics using the commercial Navier-Stokes solver STAR CCM+. The downforce lift coefficients of these wings in free flight as well as in ground effect and as the corresponding drag coefficients are presented. The best configurations of aspect ratio and angle of attack as well as the optimum distances from the ground to operate these front wings in ground effect are shown and the results discussed in detail.
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Moon, Rohini Ramrao, Shivam Prajapati, and PRAYAG RAJ MISHRA. "Aerodynamic Approach on Enhancing the Downforce in a Self-Powered Electric Vehicle." In Symposium on International Automotive Technology. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2021. http://dx.doi.org/10.4271/2021-26-0358.
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Soso, Michael, and Philip Wilson. "Investigating Changes to the Downforce Curve of a Double Element Airfoil in Ground Effect." In Motorsports Engineering Conference & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2004. http://dx.doi.org/10.4271/2004-01-3558.
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Dong, Zulong, Badih Jawad, Liping Liu, and Hossam Metwally. "Vortex Generator Designs to Improve Flow for a Vehicle Side-View Mirror." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10669.
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Abstract The unsteady airflow over automotive side-view mirrors is a typical source of turbulence which creates extra drag force, aerodynamic noise and vibration. A CFD analysis is presented for vortex generators (VGs) application on the vehicle side-view mirrors for the purpose of flow improvement. Vortex generators are used to delay flow separation and increase the control surfaces which affect the drag force and down force of the vehicle. Reduced drag force can potentially increase fuel economy, and an increased downforce will increase vehicle grip force and improve vehicle stability which is essential for racing cars. This paper presents practical solutions for mitigating flow turbulence and adjusting down force for existing side-view mirrors. Four VG configurations were designed and numerically analyzed in combination with the baseline model at air speeds ranged from 15 to 80 miles per hour. This research investigated the effect of each VG configuration on the side-view mirror’s aerodynamic performance. The turbulent flow through the side-view mirror were analyzed by using standard K-epsilon (K-ε) Reynolds-averaged Navier-Stokes method. The drag and down forces results were obtained and compared with the baseline model. The CFD analysis concluded the following: (1) Setting the VGs with a 5 degree attack angle on the upwind face of the mirror slightly reduced the drag force. (2) Setting the VGs at the top of the mirror surface greatly increased the downforce with a large drag force increase.
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Oliveira, L., B. Ortiz, R. Silva, and G. Pate. "99. Variability of the active hydraulic downforce system related to cotton seed depth and emergence." In 13th European Conference on Precision Agriculture. The Netherlands: Wageningen Academic Publishers, 2021. http://dx.doi.org/10.3920/978-90-8686-916-9_99.
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