DOCSLIB.ORG

Discussion: "An Electrical Method for Determining Journal-Bearing

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Discussion: 440 JOURNAL OF APPLIED .MECHANICS SEPTEMBER, 1953 it is very important when the two-dimensional analog}' is con- to applying the relaxation technique automatically and instan- sidered. For this application a note of warning should be added taneously at every node on the bearing surface. The question for future users of the hydraulic analogy, as pointed out pre- arises as to the accuracy of the solutions obtained using this viously by the writer.3 It must be remembered that the group electrical method. The author answers this question for the velocity of water-wave propagation will not be constant unless case of a journal bearing of infinite length. However, it is desira- the water is V-i in. deep. The group velocity is the actual rate ble to know what results this method would give when applied of propagation of the energy of the wave and is the only analogy to bearings of finite length. to the speed of sound in a gas. The group velocity is less than In order to obtain such results and to determine what diffi- the so-called wave velocity which has no analogy to the speed of culties, if any, would be encountered in applying this resistance- sound unless the water is y4 in. deep so the wave velocity be- network method to the more difficult finite-bearing problems, comes independent of wave length and equal to the group the apparatus, shown in Fig. 1 of this discussion, was built. velocity. Therefore we must restrict ourselves to 1/, in. water With this device it is possible to obtain the pressure distributions depths and weak hydraulic jumps in order to obtain equations for bearings having an L/B ratio equal to 1 (L = length per- that are comparable to those corresponding to a two-dimensional pendicular to direction of motion, B = length in direction of Downloaded from http://asmedigitalcollection.asme.org/appliedmechanics/article-pdf/20/3/440/6748130/440_2.pdf by guest on 02 October 2021 perfect gas flow with a specific heat ratio of 2. motion). As precision resistors were not available, plain '/j-watt carbon-type resistors were used throughout the apparatus. The AUTHOR'S CLOSURE commercial tolerance of the network resistors (located in Fig. 1 The author agrees with Professor Laitone's comments on approximately on the center of the board between the two banks the principles of the hydraulic analogy to compressible flow. The of switches and rheostats) was given as ±5 per cent. However, main virtue of this analogy is the fact that the behavior of the measurement of the individual resistors showed that they did not two analogous systems is governed by a similar set of nonlinear deviate more than 2 per cent from each other. This deviation equations of motion, the nonlinearity resulting in the transition was not considered serious for Liebman5 has shown that because from an elliptic to a hyperbolic type. The physical implica- of the averaging properties of resistance networks it is possible tion of this property is the creation of discontinuities appearing to obtain solutions ranging in accuracy from one part in 103 to in the form of bores in the hydraulic system and of shock waves one part in IO4 (depending upon the geometry and scale of the in the compressible flow. The electrical field does not exhibit network) when precision resistors accurate to ±1 per cent were this property and consequently the electrical system cannot be used. used for this purpose. On the other hand, the details of the proc- In the tests conducted it was thought desirable to obtain values esses such as the velocity profiles, viscosities, and so on, are not of the pressure at ten different points along the bearing surface in the same, and in particular, the energy conditions are quite dif- the direction of motion and at ten different points across the ferent. Hence the analogy can only yield information on the bearing surface, perpendicular to the direction of motion. How- "behavior or nature of the solution," as Professor Laitone rightly ever, advantage was taken of the symmetry of the pressure dis- pointed out, and any attempts to utilize it as a basis for an analog tributions which necessitated the determination of the pressures computer, similarly as it is usually done with electrical analogies, at only five different points across the bearing surface and thus are deemed to be futile. reduced the size of the required network by a factor of 2. Hence the network, rectangular in shape, was made of 10 X 5 = 50 resistors and consisted of 11 X 6 = 66 nodes. An average An Electrical Method for Determin- value of Ri (i.e., the resistors which lie along the center line of ing Journal-Bearing Characteristics1 the bearing) was 1020 ohms; Ri (all other resistors in network) averaged 515 ohms. These values were made very low in com- A. A. RAIMONDI.2 By suitable transformations, the author parison to the resistances used for regulating the input currents has succeeded for the case of journal bearings in reducing Reyn- la, for the reason set forth by the author. The bank of switches olds equation to the form3 and rheostats shown at the left in Fig. 1 were used to regulate the input currents I0, while the bank of switches and rheostats 111 at the right were used to set the leak resistances rL, to their proper !Hf f values. A precision-type potentiometer and a sensitive gal- vanometer were used for accurately setting the input currents, The partial derivatives in Equation [1 ] can be approximated by leak resistors, and for measuring the node voltages. finite-difference equations with the result that it becomes Early in the tests it was discovered that when a 135-volt B- in B\2 battery was used for supplying the input currents it was not ( — — ) ("3 + «4 — 2«o) — possible to check the node-voltage readings any closer than 4 + ff(?o) = 0 [2] per cent in some cases, depending upon the amount of time the battery was delivering current. A more satisfactory stable which can now be solved for u by applying Southwell's4 "relaxa- voltage supply was obtained by using the circuit shown in Fig. tion" method. However, the author has substituted for the 2, herewith. With this arrangement it was possible to repeat manual relaxation process an electrical method which is analogous node-voltage readings to better than 0.5 per cent accuracy. 3 "A Study of Transonic Gas Dynamics by the Hydraulic Analogy," The first pressure distribution obtained with this apparatus by E. V. Laifone, Journal of the Aeronautical Sciences, vol. 19, April, was that of a 120-deg journal bearing with Type I boundary 1952, pp. 265-272. condition having an e = 0.2, dA = 67.4 deg, and L/B = 1. In 1 By D. S. Carter, published in the March, 1952, issue of the this problem it was required to simulate four negative leak JOURNAL OF APPLIED MECHANICS, Trans. ASME, vol. 74, pp. 114- 118. resistors near the entering edge of the bearing along a line of 2 Research Engineer, Mechanics Department, Westinghouse Elec- nodes perpendicular to the direction of motion. This condition tric Corporation, East Pittsburgh, Pa. Jun. ASME. was handled with little difficulty by the method given by the 3 The nomenclature used in this discussion is the same as that used in the paper. 6 "Solution of Partial Differential Equations With a Resistance 4 "Relaxation Methods in Engineering Science," by R. V. South- Network Analogue," by G. Liebman, British Journal of Applied well, Clarendon Press, Oxford, England, 1940. Physics, vol. 1, 1950, pp. 92-103. Copyright © 1953 by ASME DISCUSSION 441 Downloaded from http://asmedigitalcollection.asme.org/appliedmechanics/article-pdf/20/3/440/6748130/440_2.pdf by guest on 02 October 2021 FIG. 1 RESISTANCE-NETWORK APPARATUS TO NETWORK NODES. QC 3/VR IQ5 FIG. 2 VOLTAGE-SUPPLY CIRCUIT author. Needs6 also had obtained the pressure distribution for this same bearing by using the electrolytic-tank method de- veloped by Kingsbury.7 Thus it was possible to compare the pressure distributions obtained by two different experimental methods. Fig. 3 of this discussion shows this comparison, the circles being the test results and the full curves graphical inter- polations from the data of Needs. It is evident that the two methods give pressure values which agree quite closely. The load-carrying capacity of this bearing was obtained using 40 60 80 graphical integration methods and was found to be <jl (DEGREES) HUR*L FIG. 3 COMPARISON OP PRESSURE-DISTRIBUTION METHODS BY IF = 0.316 , (resistance network) THE AUTHOR AND BY NEEDS C2 If this is compared to the load given by Needs for the same bear- Then ing bh d/i dx h, HUR'L h' = — = — — = - - (o - 1) [4a] TF = 0.319 • -, (Needs) of Ox of n C2 it will be seen that the two values agree within 1 per cent. and since The resistance-network method is not restricted to journal bear- ings but is equally applicable to slider bearings and, indeed, H = h'/> = j^a — (a — 1)J [46] bearings having odd film shapes resulting from distortion, mis- alignment, and so on. In order to set up these problems on the then resistance network, it is necessary to introduce the proper equa- tion for the film shape into the general equations developed by -'A .... [4c] the author. For example, for a slider bearing, the film thickness 4 ?i2 L ] at any point, x, along the bearing is expressed by Substituting the foregoing into the author's Equation [5], dividing by fi/io-1/2 and setting q proportional to the new func- h r ho.
Load more

Recommended publications
  • Tesla's Fluidic Diode and the Electronic-Hydraulic Analogy Quynh M
    Tesla's fluidic diode and the electronic-hydraulic analogy Quynh M. Nguyen, Dean Huang, Evan Zauderer, Genevieve Romanelli, Charlotte L. Meyer, and Leif Ristroph Citation: American Journal of Physics 89, 393 (2021); doi: 10.1119/10.0003395 View online: https://doi.org/10.1119/10.0003395 View Table of Contents: https://aapt.scitation.org/toc/ajp/89/4 Published by the American Association of Physics Teachers ARTICLES YOU MAY BE INTERESTED IN Euler's rigid rotators, Jacobi elliptic functions, and the Dzhanibekov or tennis racket effect American Journal of Physics 89, 349 (2021); https://doi.org/10.1119/10.0003372 Acoustic levitation and the acoustic radiation force American Journal of Physics 89, 383 (2021); https://doi.org/10.1119/10.0002764 How far can planes and birds fly? American Journal of Physics 89, 339 (2021); https://doi.org/10.1119/10.0003729 A guide for incorporating e-teaching of physics in a post-COVID world American Journal of Physics 89, 403 (2021); https://doi.org/10.1119/10.0002437 Gravitational Few-Body Dynamics: A Numerical Approach American Journal of Physics 89, 443 (2021); https://doi.org/10.1119/10.0003728 Frequency-dependent capacitors using paper American Journal of Physics 89, 370 (2021); https://doi.org/10.1119/10.0002655 Tesla’s fluidic diode and the electronic-hydraulic analogy Quynh M. Nguyen,a) Dean Huang, Evan Zauderer, Genevieve Romanelli, Charlotte L. Meyer, and Leif Ristrophb) Applied Math Lab, Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (Received 9 March 2020; accepted 10 October 2020) Reasoning by analogy is powerful in physics for students and researchers alike, a case in point being electronics and hydraulics as analogous studies of electric currents and fluid flows.
    [Show full text]
  • Acknowledgement
    SRI CHAITANYA TECHNO SCHOOL MARATHAHALLI, BANGALORE CHEMISTRY INVESTIGATORY PROJECT 2015-2016 STUDENT NAME: NAREN.K CLASS: XII HTNO: ACKNOWLEDGEMENT I am greatly indebted towards the principal for giving me an opportunity in elaborating my 2 knowledge towards the subject (CHEMISTRY) by completing this project work. I express my heartiest gratitude for the given guidance and providing the required apparatus to perform my project work. I am thankful to MR._______________ and MR.____________ for their liberal guidance. I would also thank my parents for giving me their cooperation in completing this project work. CERTIFICATE DEPARTMENT OF CHEMISTRY REGNO: 3 Certified that this is a bonafide Project work done in Physics Laboratory by MR. NAREN.K of class XII for the academic year 2015-2016 HTNO: EXTERNAL EXAMINER INTERNAL EXAMINER INDEX INVESTIGATORY PROJECT REPORT (i) Aim (ii) Materials required (iii) Theory (iv) Procedure (v) Observations and Calculations (vi) Conclusion 4 5 INVESTIGATORY PROJECT TO: - STUDY THE FOAMING CAPACITY OF DIFFERENT SOAPS 6 1. AIM: - To verify that 63% charge is stored in a capacitor in a R-C circuit at its time constant and 63% charge remains when capacitor is discharged and hence plot a graph between voltage and time 2. INTRODUCTION: - An R-C circuit is a circuit containing a resistor and capacitor in series to a power source. Such circuits find very important applications in various areas of science and in basic circuits which act as building blocks of modern technological devices. It should be really helpful if we get comfortable with the terminologies charging and discharging of capacitors.
    [Show full text]
  • Matthews Engineering 17 Fall 2020 Introduction to Kirchhoff's Laws
    Matthews Engineering 17 Fall 2020 Introduction to Kirchhoff’s laws Gustav Robert Kirchhoff, a German physicist, expressed two laws that characterize the behavior of electric circuits. Kirchoff’s current law (KCL): We have so far used the assumption that the current flowing into one terminal of a two-terminal element must be equal to the current flowing out of the other terminal of that element. Consider the hydraulic analogy of water in a pipe to current in a wire. For a single piece of pipe, the flow rate of water entering the pipe must equal the flow rate of water leaving that pipe. Suppose that the flow rate entering is 2 ft3 per minute (2 cfm). Then if the pipe is rigid and the water does not compress, the flow rate leaving must be 2cfm. Water in Pipe Water out 2cfm 2cfm Now, if there is a “Tee” connector in the pipe, how do we extend the principle above? Matthews Engineering 17 Fall 2020 Water in 1 cfm Water in Water out 2 cfm 3 cfm From the figure above, we see that the algebraic sum of all the flow rates is zero. Suppose we define flow entering positive and flow leaving negative. This gives 2+ 1 + ( − 3) = 0. Or we could define flow entering as negative and flow leaving as positive. This gives (− 2) + ( − 1) + (3) = 0. Kirchoff’s current law (KCL) states that the algebraic sum of currents entering a node is equal to zero. Example: iR 1A 2A 3A 2 vR For the circuit above, what is vR ? Matthews Engineering 17 Fall 2020 First, identify the nodes in the circuit.
    [Show full text]
  • Quantum Mechanics Ohm's Law
    Quantum Mechanics_Ohm's law This article is about the law related to electricity. For other uses, see Ohm's acoustic law. V, I, and R, the parameters of Ohm's law. Ohm's law states that the current through a conductor between two points is directlyproportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance,[1] one arrives at the usual mathematical equation that describes this relationship:[2] where I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, andR is the resistance of the conductor in units of ohms. More specifically, Ohm's law states that the R in this relation is constant, independent of the current.[3] The law was named after the German physicistGeorg Ohm, who, in a treatise published in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire. He presented a slightly more complex equation than the one above (see Historysection below) to explain his experimental results. The above equation is the modern form of Ohm's law. In physics, the term Ohm's law is also used to refer to various generalizations of the law originally formulated by Ohm. The simplest example of this is: where J is the current density at a given location in a resistive material, E is the electric field at that location, and σ is a material dependent parameter called the conductivity. This reformulation of Ohm's law is due to Gustav Kirchhoff.[4] History In January 1781, before Georg Ohm's work, Henry Cavendish experimented withLeyden jars and glass tubes of varying diameter and length filled with salt solution.
    [Show full text]
  • Inductors ECEN 1400 Introduction to Analog and Digital Electronics
    •Lecture 12: Inductors ECEN 1400 Introduction to Analog and Digital Electronics Inductors • Hydraulic analogy • Duality with capacitor • Charging and discharging Robert R. McLeod, University of Colorado http://hilaroad.com/camp/projects/magnet.html 99 •Lecture 12: Inductors ECEN 1400 Introduction to Analog and Digital Electronics The Inductor Packages http://www.electronicsandyou.com/electroni cs-basics/inductors.html Physics http://www.orble.com/userimages/user2207_1162388671.JPG Symbol Air core / generic Ferrite core Laminated iron core Robert R. McLeod, University of Colorado 100 •Lecture 12: Inductors ECEN 1400 Introduction to Analog and Digital Electronics Inductor hydraulics • The hydraulic analogy to an inductor is a frictionless waterwheel with mass. • Kinetic energy is stored in the wheel. • The finite mass makes the wheel resist changes in current. Wheel is initially Pump is turned on at t=0. stationary , that is, I(0)=0. …the wheel will be At a later time… turning with a finite current. If the pump belt was removed, current would continue to flow. Robert R. McLeod, University of Colorado https://ece.uwaterloo.ca/~dwharder/Analogy/Inductors/ 101 •Lecture 12: Inductors ECEN 1400 Introduction to Analog and Digital Electronics Inductor+resistor hydraulics “charging” phase Valve (switch) is open Wheel is initially stationary Pump is turned on at t=0. , that is, IINDUCTOR(0)=0. So all current initially goes through resistor according Pump is constant current to Ohm’s law. Valve (switch) is open At a later time… The wheel is turning, offering very little resistance. Thus a large current will go through the wheel. The same amount is still going through R (by Ohm’s law) but this is now a small fraction of the total current.
    [Show full text]
  • Uncovering Recent Progress in Nanostructured Light-Emitters For
    Grillot et al. Light: Science & Applications (2021) 10:156 Official journal of the CIOMP 2047-7538 https://doi.org/10.1038/s41377-021-00598-3 www.nature.com/lsa REVIEW ARTICLE Open Access Uncovering recent progress in nanostructured light-emitters for information and communication technologies ✉ Frédéric Grillot1,2 ,JiananDuan 1,3, Bozhang Dong1 andHemingHuang1 Abstract Semiconductor nanostructures with low dimensionality like quantum dots and quantum dashes are one of the best attractive and heuristic solutions for achieving high performance photonic devices. When one or more spatial dimensions of the nanocrystal approach the de Broglie wavelength, nanoscale size effects create a spatial quantization of carriers leading to a complete discretization of energy levels along with additional quantum phenomena like entangled-photon generation or squeezed states of light among others. This article reviews our recent findings and prospects on nanostructure based light emitters where active region is made with quantum-dot and quantum-dash nanostructures. Many applications ranging from silicon-based integrated technologies to quantum information systems rely on the utilization of such laser sources. Here, we link the material and fundamental properties with the device physics. For this purpose, spectral linewidth, polarization anisotropy, optical nonlinearities as well as microwave, dynamic and nonlinear properties are closely examined. The paper focuses on photonic devices grown on native substrates (InP and GaAs) as well as those heterogeneously and epitaxially grown on silicon substrate. This research pipelines the most exciting recent innovation developed around light emitters using nanostructures as gain media and highlights the importance of nanotechnologies on industry and society especially for shaping the future 1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; information and communication society.
    [Show full text]
  • Resistors, Volt and Current Imagine the Electricity
    Resistors, Volt and Current Posted on April 4, 2008, by Ibrahim KAMAL, in General electronics, tagged In this article we will study the most basic component in electronics, the resistor and its interaction with the voltage difference across it and the electric current passing through it. You will learn how to analyse simple resistor networks using nodal analysis rules. This article also shows how special resistors can be used as light and temperature sensors. Imagine the electricity As a beginner, it is important to be able to imagine the flow of electricity. Even if you’ve been told lots and lots of times how electricity is composed of electrons traveling across a conductor, it is still very difficult to clearly imagine the flow of electricity and how it is affected by Volt and Resistors. This is why I am proposing this simple analogy with a hydraulic system (figure 1), which anybody can easily imagine and understand, without pulling out complicated fluid dynamics equations. figure 1 Notice how the flow of electricity resembles the flow of water from a point of high potential energy (high voltage) to a point of low potential energy (low voltage). In this simple analogy water is compared to electrical current, the voltage Difference is compared to the head difference between two water reservoirs, and finally the valve resisting the flow of water is compared to the resistor limiting the flow of current. From this analogy you can deduce some rules that you should keep in mind during all your electronics work: Electric current through a single branch is constant at any point (exactly as you cannot have different flow rates in the same pipe; what’s getting out of the pipe must equal what’s getting in) There wont be any flow of current between two points if there is no potential difference between them.
    [Show full text]
  • 4 Reactive Circuits: Capacitors and Inductors 4.1 the Big Picture Our Circuits Thus Far Have Been Comprised of Batteries and Resistors
    4 Reactive Circuits: Capacitors and Inductors 4.1 The Big Picture Our circuits thus far have been comprised of batteries and resistors. When we place an AC voltage across a resistor, we found that we could apply the same analysis as in our DC circuits, using the RMS value for the voltage. We did not have to give any information about the frequency of the signal. This is because in our good circuit model, the current in a pure resistance responds instantaneously to the voltage. We now move to circuit elements for which there is a finite time response to a time dependant voltage, causing a frequency dependant response to the signal. The two main devices we will study are the capacitor and the inductor. A hand wavy intuition of how these devices function stems from a simple fact about the nature of electromagnetic fields. The laws of electromagnetism are provide by fundamental laws known as Maxwell's equations. One consequence of these equations is that a changing electric field creates a magnetic field, and in turn, a changing magnetic field creates an electric field. Imagine quickly ramping on an electric field giving rise to a voltage. This time dependant voltage accelerates charges in a conductor, and as they begin to move, their motion creates (time-varying) electromagnetic fields. These fields make a new time- dependant voltage, which creates a new acceleration on the charges and so on and so forth until eventually things balance out. This process is called the time response of the field and leads to the frequency dependance of the circuit.
    [Show full text]
  • New Modes of Instructions for Electrical Engineering Course Offered to Non- Electrical Engineering Majors
    Paper ID #14666 New Modes of Instructions for Electrical Engineering Course Offered to Non- Electrical Engineering Majors Seemein Shayesteh P.E., Indiana University Purdue University, Indianapolis Lecturer in the department of Electrical and Computer Engineering at Purdue School of Engineering at Indianapolis Dr. Maher E. Rizkalla, Indiana University Purdue University, Indianapolis Dr. Maher E. Rizkalla: received his PhD from Case Western Reserve University in January 1985 in electrical engineering. From January 1985 until August 1986 was a research scientist at Argonne National Laboratory, Argonne, IL while he was a Visiting Assistant Professor at Purdue University Calumet. In August 1986 he joined the department of electrical and computer engineering at IUPUI where he is now professor and Associate Chair of the department. His research interests include solid state devices, applied superconducting, electromagnetics, VLSI design, and engineering education. He published more than 175 papers in these areas. He received plenty of grants and contracts from Government and industry. He is a senior member of IEEE and Professional Engineer registered in the State of Indiana c American Society for Engineering Education, 2016 New Modes of Instructions for Electrical Engineering Course Offered to Non-Electrical Engineering Majors I. Introduction The traditional electrical circuits course within the mechanical engineering (ME) curriculum was designed to familiarize the ME students with linear circuits, including DC and AC analyses. The course was serving a narrow scope that included hands-on practice in linear circuits and on using instrumentations and equipment. The ME students were taking the introductory electrical and computer engineering course with electrical and computer engineering (ECE) students.
    [Show full text]
  • THE APPLICATION of the HYDRAULIC ANALOGIES to PROBLEMS of WO-DIMENSIONAL CO^PHESSIBLE GAS FLOW a THESIS Presented to the Faculty
    THE APPLICATION OF THE HYDRAULIC ANALOGIES TO PROBLEMS OF WO-DIMENSIONAL CO^PHESSIBLE GAS FLOW A THESIS Presented to the Faculty of the Division of Graduate Studies Georgia School of Technology In Partial Fulfillment of the Requirements for the Degree Master of Science in Aeronautical Engineering by John Elmer Hatch, Jr. March 1949 1<B& ii THE APPLICATION OF THE HYDRAULIC ANALOGIES TO PROBLEMS OF TWO-DIMECTSIONAL COMPRESSIBLE GAS FLOW Approved: r Date Approved by .Chairman y^txi^g X ItYf T $ • iii ACKNOWLEDGMENTS I wish to express my sincerest appreciation to Professor H. W. S. LaVier for his valuable aid and guidance in all phases of the work required for the completion of this project. I should also like to thank HE*, R. S. Leonard, of the Engineering Experiment Station Machine Shop, and Mr, J. E. Garrett, of the Engineering Experiment Station Photographic Laboratory, for their full cooperation in the use of their respective facilities. Constructive criticism and suggestions of the staff of the Daniel Guggenheim School of Aeronautics greatly helped in the prosecution of the problems involved in this work. fcr T&HLE 07 CONTENTS PAGE Approval Sheet * ii Acknowledgements • ill Lift of Figures v Summary • «.••.•..••••»••••••••#•••».....•.•.•..••.*••..•••••••• 1 Introduction, • 1 Theory •••»•« ••...*•• 4- Equipment , ••••••.•....•.... 13 Procedure 18 Di scus8ion •••*•••••» ••••• 19 Conclusions ••••••••».,....* »»• •••••23 He commendations • « ....23 BIBLIOGRAPHY.. , #.,.. .. 25 APPENDIX 1, Figures .. „ 2? ' fi LIST OF ILLUSTEATIONS TITLE PASS BO. General VI ew of *Vater Channel 28 General View of Water Channel 29 Top View of Variable Speed Drive Mechani sm 30 Schematic Diagram of Water Channel and Lighting Equipment, , 3I Shock Polar Diagrams For Diamond Airfoil Test Speeds , 32 Shock Polar Diagrams For Circular Arc Airfoil Test Speeds .
    [Show full text]
  • AE-201 Uu Heat Transfer Analogies A. Bhattacharyya AKTIEBOLAGET
    AE-201 UDCÄ24 O CN uu Heat Transfer Analogies A. Bhattacharyya AKTIEBOLAGET ATOMENERGI STOCKHOLM, SWEDEN 1965 AE-201 HEAT TRANSFER ANALOGIES Ajay Bhattacharyya Abstract This report contains descriptions of various analogues uti- lised to study different steady-state and unsteady-state heat trans- fer problems. The analogues covered are as follows: 1 . Hydraulic a) water flow b) air flow 2. Membrane 3. Geometric Electrical a) Electrolytic-tank b) Conducting sheet 4. Network a) Resistance b) R- C A comparison of the different analogues is presented in the form of a table. The bibliography contains 81 references, (This report was submitted to the Royal Institute of Techno- logy, Stockholm, in partial fulfilment of the preliminary require- ments for the degree of Teknologie Licentiat,,} Printed and distributed in November 1965 LIST OF CONTENTS Page Abstract 1 Introduction 3 I. Hydraulic Analogy 4 I, 1 Application in air-conditioning 8 I. 2 Application in design of regenerators 10 1.3 Steady-state heat exchangers 11 1.4 Transient conditions in parallel and counter flow heat-exchangers 14 1.5 Air-flow analogue 16 1.6 Practical problems 16 II. Membrane analogy 17 III. Geometric electrical analogues 19 III. 1 General description of the electrolytic tank analogue 21 III. 2 Axi- symmetric problems 23 III. 3 Application in refrigeration 23 IIIo 4 Distributed heat generation 25 III. 5 Temperature control 26 III. 6 Sources of error in the electrolytic tank analogue 2? HI. 7 General description of the conducting sheet analogue 28 IV. Network analogues 29 IV. 1 Network analogues for steady-state problems 31 IV.
    [Show full text]
  • A New Analogy Between Mechanics and Electricity: Pupil's
    A NEW ANALOGY BETWEEN MECHANICS AND ELECTRICITY: PUPIL’S MISCONCEPTIONS, PHYSICAL QUANTITIES AND ELECTRICAL COMPONENTS Morge Ludovic and Mercier-Dequidt Clotilde Laboratoire ACTé EA 4281, ESPE Clermont-Auvergne, Clermont Université, Université Blaise Pascal, France. Abstract: The teaching of electrocinetics has always given rise to recurrent learning difficulties, from junior high school to university. Over the last thirty years, research has made it possible to identify families of errors and to infer from these the spontaneous reasoning which causes them to be made (for summaries see e.g. Duit & vonRhöneck, 1998, Mulhall & al., 2001). This paper proposes a new mechanical analogy. The device consists of a string in a closed loop, which has been tied tightly around four pulleys fixed to a square or rectangular base. A weight hanging from a wire that has been wound round a pulley puts the string in the closed loop into motion. Friction can be applied to the string by pinching it. The speed at which the string moves depends on both the weight hanging from the pulley and the elements that are put in the circuit. The analogy aims to enable pupils to change their conceptual approach (from local reasoning to global reasoning). In this paper, the analogies (physical quantities and electrical components) are established for series circuits. Keywords : Analogy, Electricity, Mechanics, Misconceptions. INTRODUCTION : MISCONCEPTIONS IN ELECTROCINETICS Research in science education has led to the identification of several misconceptions in electrocinetics: - The single wire: some pupils think current is carried by only one wire from the generator to the receiver. This misconception is less frequent when pupils work on the notion of a closed circuit, but may recur when they start studying the capacitor charge (Clement & Steinberg, 2008).
    [Show full text]