Pumps & Physics Essay

Whats new?When I was thinking ab away which aspect of natural philosophy to investigate for my investigation, I knew it was a good idea to choose something that re solelyy interested me. At the condemnation I was becoming more and more fascinated by subatomic particles. I desired the fact that more than of it was new and not dumb properly, unlike the classical natural philosophy that e truly ace associates the subject with. Unfortunately, in high spirits energy physical science does not translate into good practical course operate. However, while reading cardinal Easy Pieces, a book adapted from Richard Feynmans famous textual matter The Feynman Lectures on natural philosophy, I noticed that a precise common daily phenomenon is still not properly unders similarlyd by physicists. Encouraged by the prospect of discovering something new, I read on.Chaotic ideasFeynman wrote (on page 66) There is a physical problem that is common to m whatsoever celestial orbits, that is ve ry old, and that has not been figure startIt is the analysis of circulating or turbulent fluidsNo-one canful analyse it from branch principlesWow something science cant explain I thought.I looked on the internet for further details and I order a poster from World Maths Year 2000 (http//www.newton.cam.ac.uk/wmy2kposters/march/), evinceing bonnie the type of unpredictable fluid motion that Feynman was writing about. Its a new and exciting branch of maths c eithered chaos theory and it is meet beginning to be understood mathematically. The main idea is that simple systems can show very complicated behaviour that jut outms to have no restate pattern. The sums that describe these systems argon difficult to get your head round and take c atomic number 18 to be way beyond my abilities as an A-Level maths student.Despite this, I felt something chaotic was an excellent phenomenon to look into for this task its a chance to do some tryal work where there isnt a perfect formula or a flawless chronicle in any textbook. I couldnt rely on distorting my results to oblige a simple law, so my experimentation had to be rigorous.LimitationsIt was important to point out a subject that was practical to investigate at school. While I was watching urine swirl down the drain as I filled the kettle at home, I wondered how widely- subprogramd machines like ships propellors cope with the unpredictable world of chaos. Propellers have an unusual and distinctive manufacture intentional to reduce turbulence. I wanted to investigate why this occurrence approach pattern whole kit so well and if it can tell us anything about turbulent liquefy. Conveniently, irrigate and propellors argon easy-to- usage in school labs (or so I thought).Best of all, I thought, if I could model the spot unless if ignore the extract of turbulent water, I could look at the mechanics of the propellor, and and so compare the theory with what happens in real life. It seemed like a good mix of fresh ideas and traditional physics problems.I talked about my plans to some of my t for for each one oneers and one of them conjureed that his son had make a PhD gunpoint in the formation of bubbles by marine propellors an effect called cavitation. This encouraged me to breed with this project, knowing that it relates to current areas of research and is an important and worthwhile topic.ResearchIt turns out that one of the most interesting applications of pumps is in exonerate engines. As fire services are public organisations they egg on in available plenty of high-quality, unleash information online. Engineering sites were also useful.* The Physics Behind FirefightingAmerican high-school physics projecthttp//ffden-2.phys.uaf.edu/212_fall2003.web.dir/Matt_Taylor/Matt1.dwt* How Fire Engines WorkGeneral informationhttp//science.howstuffworks.com/fire-engine.htm* Bedfordshire & Luton Fire and bring through ServiceMy local fire brigade, who I actually went to visit to distinguish out morehttp//www.bedsfire.gov.uk/index.htm* American Turbine Pump CalculationsWeb-based program for working out quantities in pumpinghttp//americanturbine.net/formulacalc/pump.htm* Impeller DesignThe engineering that goes into pumpshttp//homepage.mac.com/mrbach/mixdesign.htm* Firefighting.com white plagueful data on pumps scarce uses frames so I cant give a dep residueable URLhttp//www.firefighting.com* How Things WorkA simple explanation of propellers and aerofoilsLesley Firth, Kingfisher, 1983 p13* The Physics of Firefighting somewhat simple principles explainedPhysics Teacher, vol 28, p 599* FirefightingContains a bit of physics nevertheless interesting background informationJack Gottschalk, Dorling Kindersley, 2002, ISBN 0789489090, p128* Go with the flow denomination about modelling granular and fluid motionNew Scientist, 2 August 2003, p38-39Preliminary ExperimentsI wanted to find the most cost-effective propeller design. From research I found out that p ropellers have antithetical shapes for different tasks, so my first goal was to get a propeller up and working, and then look at what I could change to make it run more efficiently.These are the variants I aimed to evaluate for their effect on force-out transfer efficiency in preliminary tests* The speed of revolution* The size of the propeller* Since speed of rotation is less time over powering to collect data for, Ill look at it first. I call back to plot a graph of speed of rotation vs. output flow rate.Considering the shape of a ships propeller, I expected to be looking at these variables later on* The number of blades on the impeller* The shape of the blades* The orientation of the blades (what angle they are in relation to the axis of rotation)The physics principles that are important here are mechanical ones. The efficiency of the propeller depends on how much of its power goes into pushing water outwards and how much is wasted on heating the water up or create it to f orm whirlpools.New Scientists article Go with the flow mentioned the Bernoulli Effect, which is find on aircraft wings and on propeller blades.Lower crushhigher(prenominal) pressureA blade with a curved plane and a flat plane forces some air or water on a long-lasting route over the curve, and the rest takes the sooner flat route. The longer journey over the curved plane causes a drop in pressure, which translated to lift in planes, and thrust in propellers.According to all the textbooks, the optimum number of blades, the blade angle, the speed of rotation and the size of propeller all contribute to the efficiency. It seems like Ive got my work cut out for me. Im going to concentrate on rotation speed and its effect on water flow rate outwards. Lets see what the preliminary tests show. irrigate flows inAxlePropellerWatertight casingWater flows outPlanning lay on the line Assessment1,2Apparatus or procedure opinePrecautionsAll frame-upAccident or fireSupervise the experiment at a ll times and clear away at the end of the session. Store all equipment safely and securely.Boiling water for shaping polypropylene propellersRisk of scaldingTake care with boiling water, paying attention at all times. Stand well back from the saucepan and do not move it while the water is live(a). Use a heat-insulating towel to manipulate the hot polypropylene.Electric circuit in generalRisk of fire from short circuiting etc.Use insulated wires, keep connections clean and dry, and always supervise the apparatus while current is flowing.Do not leave the set-up unattended without unplugging the mains supply.Use wires of appropriate diam to prevent overheating resulting in fire.Rapidly rotating propellerPossibility of injury from contact with rotating blades of propellerLeave motor switched rack up until ready to record data. Take care to keep your distance from the propeller, curiously fingers.Heavy equipment (power pack, retort stands)Falling equipment could injureEnsure stands etc. are sturdily placed and avoid placing equipment near the very edge of the work bench.Power packOutput 13V 5A DCInput 230V mains ACRisk of electrocution from mains stimulant drug(risk of injury from output voltage is minimal)Keep power pack away from the wet part of the apparatus (to prevent conduction through water). In my experiment, I pass on keep all the electrics on a shelf above the level of the water-containing apparatus.Ensure all water-containing equipment is as waterproof as possible, and have towels to hand to soak up spills.Do not leave the set-up unattended without unplugging the mains supply.Preliminary findingsIn the research and principle section, I identified variables I wanted to investigate. I conducted preliminary experiments to found out which variables were the most practical to focus on. The basic aim is to condition my search down to one or possibly two variables and then find the most power-efficient value for each variable.Size of propeller was ve ry difficult to maintain since I found that the propeller give only(prenominal) stir the water unless it tightly fits the container. Small propellers did not displace any water. Only propellers with a diameter 1 or 2mm less than the diameter of the container were effective in pumping water. As such, I decided not to number investigating this variable.Angle of propeller blade inclination is possible to set out, but I found the range of angles possible with the materials I had chosen were too limited. I developed a method of cutting out rectangles of polypropene sheeting, boiling them in water and bending them to the right shape, but the blades practically snapped and it was tricky to get the blades to remain at the chosen angle as they cooled and hardened. I decided to keep blade inclination unvarying.45 baron seem to be an appropriate angle of inclination to choose for all the propellers I pass on compare, but most propellers I found photographs of from my research showed s hallower angles of blade inclination. I have decided that all my propellers allow for be inclined at 30 because it is easier to make the propellers this shape and I latch on that this is a more efficient angle than 45 since many propellers are about this angle.Speed of rotation turned out to be very simple to control with the use of the variable voltage power pack. I investigated the effect of power infix on rotation speed (or angulate speeding of the propeller as I call it from here on in).Using a stroboscope, I lay outd the linear relationship surrounded by the voltage supplying the motor (V) and the angular velocity (?) of the propeller rip off in air. I adjusted the frequency of the strobe light until the propeller appeared not to rotate.At this frequency, the time among flashes of the strobe and the time for one blade of the propeller to reach the former position of the blade earlier it is equal. If you find the angle in radians (?) between two adjacent blades and fig ure it by the frequency (f) of the stroboscope (the time between flashes), you are go away with the angular velocity (?) of the propeller, i.e. the rate of rotation.? = ?fIn the table below, V and f were determined experimentally and ? was calculated by multiplying f by ?. Since the frequency is only known to two significant figures, the angular velocity can only be determined to 2 s.f.Angle between blades, ?degrees72Angle between blades, ?radians0.4?VV02.254.256.258.7510.0013.000.25fs-101326365057740.5?rad s-101632456372930.5Once the propeller is immersed in water the relationship between ? and V changes. The relationship is non-linear and, unlike the graph above, is different for every propeller.In light of the preliminary experiments I will change this method to vary the power supplied to the drill that drives the propeller. It will not matter that the speed of rotation varies depending on how much the water resists the motion of the propeller. The only data that are needed to calculate the efficiency of the system are power input and useful power output.EfficiencyAt this point it is important to mention that I am concentrating on the efficiency of the propeller at displacing water. component efficiency = useful power output / power input carbon%, or rewritten in symbols, ? = Puseful out / Pin. Also, power input is proportional to input voltage since current is constant at 5 A in my equipment.P = VI and I = 5 Power (Watts) = 5 x voltage (Volts).Review of purpose of investigationThe focus of this investigation is to determine the optimum number of blades for a propeller to have to maximise energy-efficiency. Experiments will compare propellers with 2, 4 and 6 blades. The energy efficiency of the three propellers when displacing water will be determined and compared. Their efficiency may not be independent of the rate of rotation. This too will be investigated and analysed.The analysed results will show which of the three propellers is most energy effici ent in at each rate of rotation investigated.Extract from Eric Weissteins World of Physicshttp//scienceworld.wolfram.com/physics/Screw.htmlA screw is a simple machine that is actually a version of the inclined plane. The pitch of the screw corresponds to the inclination of the plane a higher pitch (i.e., more threads per length) means less inclination, and indeed easier turning, but also more turning that needs to be done to travel a given length. As with the former(a) simple machines, the requisite force is reduced, but the amount of work done is the same.Apparatus13V max. variable voltage power packRetort stands and clamps15 cm regulationSilicone polymer window seal offantGarden hosepipeExpanded polystyrene for supportsMultimeter (0.25V, 0.25A tolerance)polypropene sheet for making propellersPET lemonade bottles (2 Litre capacity)Plastic funnel for pickStopwatchCollection bottle with 2 litre mark ( 0.002 L)cordless electric screwdriver/drillSteel axleVolumetric burettePET pu dding basins to contain propellerWaterColour-coded wires and crocodile clipsSaucepan, hotplate and tongs for heating and reshaping polypropene into propellersScissors and craft knife for cutting out propeller shapes from polypropene sheetApparatus set-upThese plats show how I designed the equipment. The circuit diagram connected to the drill represents the power pack, and its voltage selector is displayed as a variable resistor. The plastic volute is the container that houses the propeller.To begin with, water fills the water cooler and the plastic volute. Activating the power pack supplies an electric current to the drill, which rotates the propeller.Variables to controlVariableHow I will control itViscosity of water changeless at constant temperature and pressurePower and speed of rotation of propellerUse a power pack instead of a barrage to supply the cordless drill. Use the same power pack, axle and drill throughout the experiment. Rotation speed does not vary linearly with pow er but carefully designing the experiment can avoid problems.Room temperature and pressureConstant at 20C due to central heating. atmospherical pressure changes are insignificant to this experiment.Plan for laboratory sessionsSession and distanceTargetsBefore lab work beginsBuild the waterproof sections of the apparatus and seal them with silicone polymer. Buy a cordless drill.First two hours rope up all apparatus, construct the propellers and test the experiment to ensure it works as plannedSecond two hoursMeasure the time taken to raise 2 Litres of water through 50cm vertically by each of the three propellers, with 65W power inputThird two hoursRepeat the precedent sessions experiment, but with the power set at 35W. quaternate two hoursBy considering the results collected before this session, decide which range of power input to investigate in detailFifth two hours delay gathering results for chosen range of power inputsRemaining time look into turning points and anomalies as n ecessaryIn between lab sessions exculpate results tables, draws graphs as appropriate and start to analyse findings. Use analysis to modify strategy and to make decisions on how to progress.While I was designing which equipment to use and how to use it, I thought carefully about accuracy and sensitivity. The study difficulty with this experiment is the unpredictable nature of the propellers unlike many other things physics, it is not easy to find a good estimate of what will happen in textbooks or online.One way of ensuring good results is to footfall the variables to a reasonable number of significant figures. The multimeter I chose to use is officious to respond to changes in current or potential difference and has okay graduations on its scale, providing high sensitivity. It also has very tight tolerances as it is designed for use in high performance electronics, which contributes to the accuracy of the results I will gather.The multimeter is significantly more accurate and sensitive some of the digital alternatives at school. It responds to changes much quicker too.I have had to design and build quite a a large amount of equipment just to make this project possible. To musical rhythm the batch of water pumped out by the system, I will calibrate the water collection bottle with graduations. To make sure they are very sensitive and accurate, I will use the high quality, high accuracy laboratory glassware available at school for use in chemistry and biology. The percentage error on the volume graduations on these pieces of equipment is very small (around 0.0003%).References for planning section1. Cambridge University Department of PhysicsPhysics risk assessment formhttp//www.phy.cam.ac.uk/cavendish/hands/forms/RAform.pdf2. CLEAPSS Secondary Schools websitehttp//www.cleapss.org.uk/secfr.htmImplementingModifications to plan line of workSolutionHow to water-seal the entire systemCareful application of silicone sealer and gaffer tape at all junctions. Ap paratus tested subsurface by pressurising with air using a bike pump. Leaks located by bubbles escaping where seals were incomplete.How to get water to flow from the water reservoir into the propeller cavity, without providing any extra pressure that would reduce the workload of the propellerHeight of water reservoir bottle adjusted until water just reaches the top of the propeller cavity, without spilling out the output holeHow to accurately measure the volumes of water use in each experimentVolumetric glassware borrowed from chemistry subdivisionCalculation of power efficiency of pumping system?E = mg?hP = Et-1Useful power output = power spent on raising water against the force of the Earths gravitational fieldUseful power output = (mass of water elevated (mwater) strength of sedateness at sea level (g) height through which the water is raised (?h)) / time taken (t)Pout = mwaterg?ht-1The mass of water is proportional to its volume at constant temperature and atmospheric pres sure. In these experiments, the temperature and pressure have been constant at 293K (20C) and 105 Pa respectively. Under these conditions, water has a assiduousness of 998.2 kgm-3 (according to the Nuffield Advanced Science Data Book, Nuffield-Chelsea Curriculum Trust, Longman, 1984). Therefore, the time taken to raise the water and the number of blades on each propeller are the only variables in my experiment.