Performance Measurements of a 1/6-Scale Model of the 1907 Cornu Rotor

2012 ◽  
Vol 57 (3) ◽  
pp. 1-5
Author(s):  
Benjamin Hance ◽  
J. Gordon Leishman ◽  
Joseph Milluzzo
Keyword(s):  
Aspect Ratio ◽  
Figure Of Merit ◽  
Ground Effect ◽  
Operating Conditions ◽  
Scale Model ◽  
Performance Measurements ◽  
Aerodynamic Efficiency ◽  
Rotor Design ◽  
Average Profile ◽  
And Performance

Measurements of the performance of an approximate 1/6-scale Cornu 1907 rotor system are discussed. The rotor was tested in hover, both in and out of ground effect, over a range of rotational speeds and collective blade pitch angles. The measurements showed that the rotor had low aerodynamic efficiency, with a maximum attainable figure of merit of only about 0.35 for out of ground effect operating conditions. An analysis of the measurements showed that the performance of this rotor is dominated by relatively high induced losses, with an average induced power factor of over two, mainly because of the use of low-aspect-ratio blades. Extrapolation of the performance polar back to zero thrust with the aid of modified momentum theory suggests that the average profile drag coefficient for the blade sections was of the order of 0.1. However, even with the benefits of a proper airfoil section of lower drag, it is shown that without also using a blade design of higher aspect ratio, the figure of merit of the Cornu rotor design could not be improved much above 0.4. The measured results confirm previous modeling assumptions used for the aerodynamic and performance analysis of the Cornu rotor design and conclusions drawn regarding the unfeasibility of successful free flights of the Cornu helicopter.

Experimental Investigation of Rotors Hovering above Inclined Surfaces

2020 ◽  
Author(s):  
Joseph I. Milluzzo ◽  
Aaron Martinez ◽  
Scott Drayton ◽  
Scott Davids
Keyword(s):  
Axial Velocity ◽  
Figure Of Merit ◽  
Ground Plane ◽  
Ground Effect ◽  
Plane Angle ◽  
Performance Measurements ◽  
Velocity Measurements ◽  
Wake Structure ◽  
Inclined Surfaces ◽  
Bladed Rotor

Particle image velocity measurements were taken to document the wake generated by a rotor operating in ground effect above inclined surfaces. In particular, the current work focused on the average wake structure and axial velocity distribution through the rotor. A two-bladed rotor was operated at a height of one rotor radius above a ground plane that was inclined at angles from 0° to 30°. Rotor performance measurements were also taken, using a six-axis load cell, to examine the effect ground plane angle had on the thrust produced and power required. The wake structure was found to be very sensitive to ground plane angle causing the radial distribution of axial velocity through the rotor to increase inboard and decrease outboard with increasing ground plane angle. As compared to the level ground case, the peak figure of merit of the rotor decreased by approximately 10% for a ground plane inclination angle of 30°.

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.

Bio-inspired design of flapping-wing micro air vehicles

2005 ◽  
Vol 109 (1098) ◽  
pp. 385-393 ◽  
Author(s):  
K. D. Jones ◽  
C. J. Bradshaw ◽  
J. Papadopoulos ◽  
M. F. Platzer
Keyword(s):  
Aspect Ratio ◽  
Figure Of Merit ◽  
Ground Effect ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Rechargeable Battery ◽  
Flight Testing ◽  
Low Aspect Ratio ◽  
Air Vehicles

AbstractIn this paper the development and flight testing of flapping-wing propelled, radio-controlled micro air vehicles are described. The unconventional vehicles consist of a low aspect ratio fixed-wing with a trailing pair of higher aspect ratio flapping wings which flap in counterphase. The symmetric flapping-wing pair provides a mechanically and aerodynamically balanced platform, increases efficiency by emulating flight in ground effect, and suppresses stall over the main wing by entraining flow. The models weigh as little as 11g, with a 23cm span and 18cm length and will fly for about 20 minutes on a rechargeable battery. Stable flight at speeds between 2 and 5ms–1has been demonstrated, and the models are essentially stall-proof while under power. The static-thrust figure of merit for the device is 60% higher than propellers with a similar scale and disk loading.

scholarly journals Influence of Contact Plateaus Characteristics Formed on the Surface of Brake Friction Materials in Braking Performance through Experimental Tests

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4931
Author(s):  
Rafael Lucas Machado Pinto ◽  
Juan Carlos Horta Gutiérrez ◽  
Robson Bruno Dutra Pereira ◽  
Paulo Eustáquio de Faria ◽  
Juan Carlos Campos Rubio
Keyword(s):  
Friction Pair ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Performance Measurements ◽  
Friction Materials ◽  
Braking Performance ◽  
Emergency Braking ◽  
The Coefficient Of Friction ◽  
And Performance

This work applies a procedure for analysis and characterization of the surface of brake friction materials, correlating them with the tribological and thermal properties achieved in different vehicle braking conditions. Experiments were performed in a vehicle under two real conditions of braking operation, simulated flat track descent and emergency braking. Characteristics of the plates formed on the surfaces of the friction materials were analyzed by scanning electron microscopy (SEM) and correlated with the performance during braking, as measured by the coefficient of friction at the interface of the friction pair and temperature. As a result, the formation of the primary and secondary plateaus in these two different braking operating conditions was observed, and the relationship between the characteristics of the plateaus formed on the surface and the surface roughness parameters and performance measurements during braking.

Design and Development of the Atlas Human-Powered Helicopter

2015 ◽  
Vol 60 (1) ◽  
pp. 1-15
Author(s):  
Cameron D. Robertson ◽  
Todd M. Reichert
Keyword(s):  
Ground Effect ◽  
Element Analysis ◽  
Composite Failure ◽  
Aerodynamic Model ◽  
Rotor Design ◽  
Dynamics And Control ◽  
Estimation Scheme ◽  
And Performance ◽  
Human Powered ◽  
And Control

AeroVelo initiated the Atlas Human-Powered Helicopter Project in August 2011 to win the AHS Sikorsky Prize, which despite prior attempts had remained unclaimed for over 30 years. The Sikorsky Prize required a human-powered helicopter to sustain flight for 60 s, momentarily reach a height of 3 m, and maintain position within a 10 m × 10 m area. A configuration study was undertaken using low-fidelity aerodynamic analysis and estimated mass figures. An aerostructural optimization framework was developed for rotor design, including a novel vortex-ring aerodynamic model with included ground effect prediction, finite-element analysis including integrated composite failure analysis, and a detailed weight estimation scheme. The airframe was composed of a wire-braced truss structure, and innovative designs were developed for many of the aircraft's lightweight-focused subsystems. After initial flight testing in August 2012, experimental optimization and performance improvement led to a second testing program beginning in January 2013. Testing in 2013 led to a reduction in required power, improved understanding of structural dynamics, and control strategy. The project culminated with the successful AHS Sikorsky Prize flight on June 13, 2013.

Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

2013 ◽  
Vol 41 (2) ◽  
pp. 127-151
Author(s):  
Rudolf F. Bauer
Keyword(s):  
Finite Element ◽  
Aspect Ratio ◽  
Finite Element Methods ◽  
Mathematical Analysis ◽  
Internal Stresses ◽  
Stress Concentrations ◽  
Equilibrium Profiles ◽  
Equilibrium Profile ◽  
And Performance ◽  
Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

MODERN EQUIPMENT FOR DETERMINING TRACTOR-SPEED PROPERTIES OF THE VEHICLE: CHARACTERISTICS’ ANALYSIS IN LABORATORY CONDITIONS

2019 ◽  
Vol 16 (3) ◽  
pp. 276-289
Author(s):  
N. V. Savenkov ◽  
V. V. Ponyakin ◽  
S. A. Chekulaev ◽  
V. V. Butenko
Keyword(s):  
Environmental Performance ◽  
Operating Conditions ◽  
Special Role ◽  
Development Stages ◽  
Advantages And Disadvantages ◽  
Force Transfer ◽  
Characteristics Analysis ◽  
And Performance ◽  
Loading Devices ◽  
Structural Solutions

Introduction. At present, stands with running drums are widely used for various types of tests. Power stands play a special role. Such stands take the mechanical power from the driving wheels of the car. This simulates the process of movement of the vehicle under operating conditions. Such equipment has various designs, principles of operation and performance. It is also used in tests that are different by purpose, development stages and types: research, control, certification, etc. Therefore, it is necessary in order to determine the traction-speed, fuel-efficient and environmental performance characteristics.Materials and methods. The paper provides the overview of the power stands with running drums, which are widespread on the domestic market. The authors carried out the analysis of the main structural solutions: schemes of force transfer between the wheel and the drum; types of loading devices; transmission layout schemes and features of the control and measuring complex. The authors also considered corresponding advantages and disadvantages, recommended spheres of application, demonstrated parameters and characteristics of the units’ workflow, presented components and equipment.Discussion and conclusions. The authors critically evaluate existing models of stands with running drums. Such information is useful for choosing serial models of stands and for developing technical tasks for designing or upgrading the equipment.

Application of vacuum belt press filters for cane mud filtration and performance comparison with rotary filters

2014 ◽  
pp. 298-301 ◽  
Author(s):  
Arnaud Petit
Keyword(s):  
Electricity Consumption ◽  
Performance Comparison ◽  
Operating Conditions ◽  
Vacuum Filter ◽  
Sugar Mill ◽  
Belt Press ◽  
Vacuum Belt ◽  
And Performance ◽  
Mud Filtration ◽  
The Impact

Bois-Rouge factory, an 8000 t/d cane Reunionese sugarcane mill, has fully equipped its filtration station with vacuum belt press filters since 2010, the first one being installed in 2009. The present study deals with this 3-year experience and discusses operating conditions, electricity consumption, performance and optimisation. The comparison with the more classical rotary drum vacuum filter station of Le Gol sugar mill highlights advantages of vacuum belt press filters: high filtration efficiency, low filter cake mass and sucrose content, low total solids content in filtrate and low power consumption. However, this technology needs a mud conditioning step and requires a large amount of water to improve mud quality, mixing of flocculant and washing of filter belts. The impact on the energy balance of the sugar mill is significant. At Bois-Rouge mill, studies are underway to reduce the water consumption by recycling low d.s. filtrate and by dry cleaning the filter belts.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

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