scholarly journals Aerodynamic Performance of an Octorotor SUAV with Different Rotor Spacing in Hover

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1364
Author(s):  
Yao Lei ◽  
Yuhui Huang ◽  
Hengda Wang
Keyword(s):  
Flow Field ◽  
Unmanned Aerial Vehicles ◽  
Aerodynamic Performance ◽  
Aerodynamic Efficiency ◽  
Experimental Platform ◽  
Vorticity Distribution ◽  
Aerial Vehicles ◽  
Spacing Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

To study the aerodynamic performance of hovering octorotor small unmanned aerial vehicles (SUAV) with different rotor spacing, the computational fluid dynamics (CFD) method is applied to analyze the flow field of an octorotor SUAV in detail. In addition, an experimental platform is built to measure the thrust and power of the rotors with rotor spacing ratios L/D of 1.0, 1.2, 1.4, 1.6, and 1.8, sequentially. According to the theory of momentum, rotor aerodynamic performance is obtained with qualitative analysis. Further analysis with numerical simulation is presented with the flow field of the octorotor SUAV, the vorticity distribution, velocity distribution, pressure distribution, and streamline. The results show that the aerodynamic performance varies with the rotor spacing. Specifically, the aerodynamic performance is poor at L/D = 1.0, which is accompanied with strong interaction of wake and tip vortexes and interaction with each other. However, the aerodynamic efficiency is much improved with a larger rotor spacing, especially achieving the highest at L/D = 1.8, which is considered to be the best rotor spacing ratio for this kind of octorotor SUAV.

scholarly journals A Comparison of Isolated and Ducted Fixed-Pitch Propellers under Non-Axial Inflow Conditions

Aerospace ◽  
2020 ◽  
Vol 7 (8) ◽  
pp. 112
Author(s):  
Michael Cerny ◽  
Christian Breitsamter
Keyword(s):  
Flow Field ◽  
Unmanned Aerial Vehicles ◽  
Systematic Investigation ◽  
Major Influence ◽  
Small Scale ◽  
Highly Efficient ◽  
Strong Interest ◽  
Aerial Vehicles ◽  
Inflow Conditions ◽  
Fixed Pitch

A strong interest in highly-efficient, small-scale propeller configurations can be recognized, especially due to the currently growing number of and usage possibilities for unmanned aerial vehicles (UAVs). Although a variety of different propulsion concepts already exist on the market or are discussed in the literature, there is still a demand for a systematic investigation to compare such configurations, in particular, small-scale propellers with a fixed pitch, which are analyzed in this work. Therefore, different configurations of small-scale propellers with a fixed pitch are analyzed in this paper. They were operated as isolated single propellers and as ducted propellers in a cylindrical wing. Furthermore, due to their flight envelope, UAVs are likely to operate at highly inclined inflow conditions and even under reverse inflow. These non-axial inflow conditions have a major influence on the flow field around a propeller. In order to investigate this influence, all analyses were performed at a range of inflow angles in relation to the propeller axis from αdisc=0° to 180°.

scholarly journals Simulation and Test of Discrete Mobile Surfaces for a RC-Aircraft

Aerospace ◽  
2019 ◽  
Vol 6 (11) ◽  
pp. 122
Author(s):  
Francesco Nicassio ◽  
Gennaro Scarselli
Keyword(s):  
Composite Materials ◽  
Unmanned Aerial Vehicles ◽  
Composite Plate ◽  
Stacking Sequence ◽  
Total Thickness ◽  
Aerodynamic Efficiency ◽  
Aerodynamic Pressure ◽  
Aerial Vehicles ◽  
Discrete Surface ◽  
Lever Effect

Morphing structures suitable for unmanned aerial vehicles (UAVs) have been investigated for several years. This paper presents a novel lightweight, morphing concept based on the exploitation of the “lever effect” of a bistable composite plate that can be integrated in an UAV horizontal tail. Flight dynamics equations are solved in Simulink environment, thus being able to simulate and compare different flight conditions with conventional and bistable command surfaces. Subsequently, bistable plates are built by using composite materials, paying particular attention to dimensions, asymmetric stacking sequence and total thickness needed to achieve bistability. NACA0011 airfoil is chosen for proving this concept. Wind tunnel tests demonstrate that the discrete surface is capable of withstanding the aerodynamic pressure. A remotely piloted vehicle is employed to test the discrete horizontal tail command during the take-off. The results show that, choosing a proper configuration of constraints, stacking sequence and aspect ratio for the bistable laminate, it is possible to tailor the snap-through mechanism. The proposed concept appears lighter and increases aerodynamic efficiency when compared to conventional UAV command surfaces.

Numerical Simulation of the Laminar Flow Field in Stirred Tank with Double Layer Combined Impeller Stirring Eccentrically

2015 ◽  
Vol 779 ◽  
pp. 125-132
Author(s):  
Ying Na Liang
Keyword(s):  
Flow Field ◽  
Double Layer ◽  
Three Dimensional ◽  
Stirred Tank ◽  
Flow Structures ◽  
Practical Application ◽  
Three Dimensional Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Multiple Reference

Computational fluid dynamics (CFD) method was applied to study the flow field in cylindrical stirred tank mixing non-Newtonian fluid with double layer combined impeller of upper-straight-blade and lower-inclined-blade. The laminar model and the multiple reference frame (MRF) were employed to simulate the three-dimensional flow field in stirred tank with double layer combined impeller rotating at a constant speed of 200 r/min mixing the mixture of glycerin and water centrally、eccentrically and relative eccentrically, and three different flow structures in stirred tank were obtained. Analyzing the velocity vectors, the velocity contours and the axial、radial and tangent velocity distribution curves, the rule of velocity field with the blade combined form and the stirring structure was discussed. The research provided the valuable reference for the design and practical application of the laminar stirred tank.

Viability of joined flight for small unmanned aerial vehicles

2019 ◽  
Vol 124 (1273) ◽  
pp. 297-322
Author(s):  
E. Levis ◽  
F. Pleho ◽  
J. Hedges
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Parametric Analysis ◽  
Aircraft Design ◽  
Relative Magnitude ◽  
Design Parameters ◽  
Wing Loading ◽  
Aerodynamic Efficiency ◽  
Aspect Ratios ◽  
Aerial Vehicles ◽  
Better Than

ABSTRACTThe range of small, electrically powered UAVs is still limited by the mass specific energy of batteries. This paper investigates the idea that, in cases where multiple aircraft must transit to the same location, savings in mass or an extension of achievable range are possible when they join wingtip-to-wingtip. The viability of joined flight is investigated by quantifying the relative magnitude of savings resulting from increased aerodynamic efficiency and that of penalties due to the increased structural and component weights. Through a parametric analysis the level of savings achievable is found to be greatly dependent on the proportion of the flight spent in a joined configuration and aircraft design parameters such as wing loading, aspect ratio and the added weight of the joining mechanism. A custom, multidisciplinary UAV sizing algorithm is presented and utilised to design several sample aircraft, featuring two different joining mechanism architectures. The results verify the findings of the parametric study and indicate that mass savings are possible only for moderate to low aspect ratios, with semi-permanent magnetic joining mechanism performing better than rigid structural ones, even when the joined fight segment accounts for only 30% of the total airborne time.

scholarly journals Effect of Wing Corrugation on the Aerodynamic Efficiency of Two-Dimensional Flapping Wings

2020 ◽  
Vol 10 (20) ◽  
pp. 7375
Author(s):  
Thanh Tien Dao ◽  
Thi Kim Loan Au ◽  
Soo Hyung Park ◽  
Hoon Cheol Park
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Two Dimensional ◽  
Aerodynamic Efficiency ◽  
Insect Wing ◽  
Wing Motion ◽  
Computational Fluid Dynamics Cfd

Many previous studies have shown that wing corrugation of an insect wing is only structurally beneficial in enhancing the wing’s bending stiffness and does not much help to improve the aerodynamic performance of flapping wings. This study uses two-dimensional computational fluid dynamics (CFD) in aiming to identify a proper wing corrugation that can enhance the aerodynamic performance of the KUBeetle, an insect-like flapping-wing micro air vehicle (MAV), which operates at a Reynolds number of less than 13,000. For this purpose, various two-dimensional corrugated wings were numerically investigated. The two-dimensional flapping wing motion was extracted from the measured three-dimensional wing kinematics of the KUBeetle at spanwise locations of r = (0.375 and 0.75)R. The CFD analysis showed that at both spanwise locations, the corrugations placed over the entire wing were not beneficial for improving aerodynamic efficiency. However, for the two-dimensional flapping wing at the spanwise location of r = 0.375R, where the wing experiences relatively high angles of attack, three specially designed wings with leading-edge corrugation showed higher aerodynamic performance than that of the non-corrugated smooth wing. The improvement is closely related to the flow patterns formed around the wings. Therefore, the proposed leading-edge corrugation is suggested for the inboard wing of the KUBeetle to enhance aerodynamic performance. The corrugation in the inboard wing may also be structurally beneficial.

scholarly journals Aerodynamic Optimization of a Micro Quadrotor Aircraft with Different Rotor Spacings in Hover

2020 ◽  
Vol 10 (4) ◽  
pp. 1272 ◽  
Author(s):  
Yao Lei ◽  
Hengda Wang
Keyword(s):  
Numerical Simulations ◽  
Negative Impact ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Aerodynamic Optimization ◽  
Quadrotor Aircraft ◽  
Blade Tip ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Interference ◽  
Cfd Method

In order to study the aerodynamic performance of the quadrotor with different rotor spacings in hover, experiments were performed together with numerical simulations. For experimental study, an experimental platform was designed to measure the thrust and power consumption of the quadrotor with different rotor spacings (L/R = 2.2, 2.6, 3.0, 3.2, 3.6, and 4.0), and to attempt to find out the optimal rotor configuration which makes the quadrotor have the best aerodynamic performance. In addition, the pressure distribution, vorticity of the blade tip, and velocity vector of quadrotor in the flow field were obtained by Computational Fluid Dynamics (CFD) method to visually analyze the aerodynamic interference between adjacent rotors. By the comparison of experimental results and numerical simulations, the final results show that the aerodynamic performance of the quadrotor varies obviously with the change of rotor spacing, and it has a negative impact on hover efficiency if rotor spacing is too much small or large. The rotors pacing at L/R = 3.6 with larger thrust and smaller power is considered to be the best aerodynamic configuration for the quadrotor with better aerodynamic characteristics. Furthermore, compared with the isolated rotor, moderate aerodynamic interference is proved to help improve the aerodynamic performance of the quadrotor with a larger thrust, especially for a rotor spacing at L/R = 3.6.

Influence Mechanisms of Manufacture Variations on Supersonic/Transonic Blade Aerodynamic Performances

2020 ◽  
Author(s):  
Baojie Liu ◽  
Jiaxin Liu ◽  
Xianjun Yu ◽  
Dejun Meng ◽  
Wenbin Shi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Statistical Analysis ◽  
Mach Number ◽  
Systematic Errors ◽  
Aerodynamic Performance ◽  
Aerodynamic Performances ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Abstract The results of previous studies have proved that manufacture variations can cause a noticeable influence on compressor aerodynamic performance. The main objective of this paper is to investigate the influence rules and mechanisms of manufacture variations on supersonic/transonic blades aerodynamic performance. The variations used in this study were measured from some newly manufactured high-pressure compressors. In the present study, several blade sections with different design Mach number conditions are selected for further statistical analysis of measured deviation data. Therefore, some systematic errors in the deviation data have been revealed. Based on these data, the computational fluid dynamics (CFD) method has been used to obtain the aerodynamic performances of a large number of the measured blade elements. And then, the analysis of the influence rules of manufacture variations on blade aerodynamic performance in different Mach number conditions has been carried out. The present results indicate that the effects of manufacture variations on blade aerodynamic performance in the lower Mach number (0.8) condition are much more significant comparing to that in the higher Mach number (0.9∼1.2) conditions. Based on this, influence mechanisms of manufacture variations on positive incidence range and negative incidence range have been analyzed. The differences of influence mechanisms in different Mach number conditions are the focus of research.

Numerical Analysis of a Centrifugal Fan for a Road Sweeper

2017 ◽  
Author(s):  
Xiaoxuan Chen ◽  
Mingyang Yang ◽  
Kangyao Deng ◽  
Yunlong Bai
Keyword(s):  
Flow Field ◽  
Field Analysis ◽  
Centrifugal Fan ◽  
Suction Force ◽  
Flow Loss ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Field Analysis ◽  
Cfd Method ◽  
Original Configuration ◽  
Inlet Duct

Road sweeper is the widely-employed machine to clear up garbage and dust on streets. Its performance has profound influence on the reduction of fuel consumption and hence CO2 emission. The key component of a road sweeper is a centrifugal fan which produces suction force for clearing. Therefore, the performance of this device has direct impact on fuel economy of the machine. This paper targets at the performance analysis of a centrifugal fan in a commercial road sweeper. Firstly, the performance and flow field of the centrifugal fan are analyzed by computational fluid dynamics (CFD) method. The breakdown of the flow loss in the fan shows that the volute and the impeller are major components contributing to flow loss in the fan. The flow at the inlet of the impeller is highly distorted due the interaction among the asymmetrical inlet duct, the leakage and the volute tongue. Because of the interaction, flow passages near the tongue are the ones with the highest flow loss. Moreover, the flow velocity entering the volute is considerably high which thus results in high flow loss in the volute. Finally, based on the flow field analysis, an inlet duct with round shape is designed preliminarily and simulated together with the centrifugal fan. The results show that the efficiency can be improved by more than 4% compared with the original configuration due to the alleviation of the interaction.

scholarly journals Aerodynamic efficiency and performance enhancement of fixed-wing unmanned aerial vehicles using novel configurations and techniques

2018 ◽  
Author(s):  
Περικλής Παναγιώτου
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Performance Enhancement ◽  
Operating Conditions ◽  
Aerodynamic Efficiency ◽  
Aerial Vehicles ◽  
And Performance

Ο σκοπός της διδακτορικής διατριβής είναι η βελτιστοποίηση της αεροδυναμικής απόδοσης και των επιδόσεων Μη-Επανδρωμένων Αεροχημάτων (ΜΕΑ) σταθερής πτέρυγας, μεγάλης αυτονομίας και μέσου ύψους (MALE UAV ή tactical UAV – NATO classification), που επιχειρούν σε συνθήκες πτήσης με Mach < 0.3. Πρόκειται για μια πλήρη τεχνολογική έρευνα, τα βασικά αντικείμενα της οποίας είναι α) η διερεύνηση της ροής γύρω από ΜΕΑ σταθερής πτέρυγας, β) η ανάλυση του ισοζυγίου οπισθέλκουσας δύναμης και εντοπισμός των κύριων πηγών αυτής, γ) η αναζήτηση, καταγραφή, και αξιολόγηση πιθανών τεχνολογιών, γεωμετριών, και τεχνικών για τη βελτίωση της αεροδυναμικής απόδοσης και των επιδόσεων ΜΕΑ (technology screening), δ) η επιλογή και λεπτομερής διερεύνηση των γεωμετριών που δυνητικά προσφέρουν τα περισσότερα πλεονεκτήματα, και ε) η εφαρμογή των παραπάνω σε εφαρμοσμένες μελέτες σχεδιασμού ΜΕΑ για αξιολόγηση και εκτίμηση επιδόσεων. Σε αντίθεση με τις υπάρχουσα βιβλιογραφία, η παρούσα έρευνα προσεγγίζει ολιστικά τον σχεδιασμό και την βελτιστοποίηση των ΜΕΑ σταθερής πτέρυγας, εκκινώντας από θεμελιώδεις ρευστοδυναμικές αναλύσεις, συνεχίζοντας με παραμετρικές αναλύσεις αεροδυναμικής, και κλείνοντας με εφαρμογή σε ολοκληρωμένες μελέτες σχεδιασμού. Για αυτό το σκοπό χρησιμοποιείται μια πληθώρα εργαλείων, που περιλαμβάνουν λογισμικά υπολογιστικής μοντελοποίησης, πειραματικές διατάξεις και τεχνικές, καθώς επίσης και αναλυτικά εργαλεία διαστασιολόγησης, και υπολογισμού παραμέτρων αεροδυναμικής, ευστάθειας και επιδόσεων αεροχημάτων, που αναπτύχθηκαν στα πλαίσια της διατριβής (in-house tools). Αρχικά καθορίζεται και σχεδιάζεται μια γεωμετρία αναφοράς ΜΕΑ, της οποίας οι προδιαγραφές (requirements) και οι επιχειρησιακές συνθήκες (operating conditions) ορίζονται επίσης ως σημεία αναφοράς. Η ροή γύρω από το ΜΕΑ αναλύεται χρησιμοποιώντας τα εργαλεία αεροδυναμικής ανάλυσης και πραγματοποιείται μια ταξινόμηση της οπισθέλκουσας δύναμης (drag bookkeeping), τόσο για την κύρια πτέρυγα, όσο και για την συνολική γεωμετρία του ΜΕΑ. Στη συνέχεια, ερευνάται μια πληθώρα πιθανών επιλογών, τεχνολογιών, τεχνικών και γεωμετριών, που δυνητικά μπορεί να βελτιώσουν την επίδοση των ΜΕΑ σταθερής πτέρυγας. Δύο είδη γεωμετριών επιλέγονται τελικά για ενδελεχή μελέτη και περεταίρω ανάλυση, και συγκεκριμένα, τα winglets και τα σώματα BWB. Οι γεωμετρίες αυτές αναλύονται διεξοδικά σε υπολογιστικό, πειραματικό, και σχεδιαστικό επίπεδο. Όπως πιστοποιείται και από τις σχετικές επιστημονικές δημοσιεύσεις, η έρευνα οδηγεί σε πρωτότυπα συμπεράσματα και παρατηρήσεις που αφορούν τα ροϊκά φαινόμενα, και σε ανάπτυξη εξειδικευμένων μεθοδολογιών σχεδιασμού για εφαρμογές ΜΕΑ σταθερής πτέρυγας. Γίνεται επίσης και αποτίμηση των πλεονεκτημάτων της χρήσης των γεωμετριών αυτών, με τα αποτελέσματα να δείχνουν βελτίωση της τάξεως του 10% και 30% για τα winglets και τις πλατφόρμες BWB αντίστοιχα, όσον αφορά την αεροδυναμική απόδοση. Συνοψίζοντας, η διατριβή επικεντρώνεται στα ΜΕΑ τύπου MALE/tactical, λόγω του ότι αποτελούν το μεγαλύτερο κομμάτι της αγοράς των ΜΕΑ. Ωστόσο, με την προϋπόθεση ότι οι λόγοι ροϊκής ομοιότητας και οι επιχειρησιακές συνθήκες είναι πανομοιότυπες, οι προτεινόμενες μέθοδοι και τα επαγόμενα συμπεράσματα μπορούν να επεκταθούν και σε οποιοδήποτε άλλο αερόχημα σταθερής πτέρυγας, από ΜΕΑ μεγαλύτερης κλίμακας, μέχρι υπερ-ελαφρά ή ελαφρά αεροχήματα και μεταγωγικά αεροσκάφη. Επιπρόσθετα, η έρευνα που αφορά είτε σε στοιχειώδη ρευστοδυναμικά φαινόμενα, όπως είναι οι δίνες ακροπτερυγίου, είτε στις βελτιωτικές διατάξεις (winglets, BWB) έχει προεκτάσεις και σε άλλες εφαρμογές μεγαλύτερης κλίμακας, που αφορούν την κοινωνία και την βιομηχανία, όπως είναι για παράδειγμα τα επιβατηγά αεροσκάφη και οι εναέριες μεταφορές.

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