What is Engine: Definition and 999 Discussions

An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines convert heat into work via various thermodynamic processes. The internal combustion engine is perhaps the most common example of a heat engine, in which heat from the combustion of a fuel causes rapid pressurisation of the gaseous combustion products in the combustion chamber, causing them to expand and drive a piston, which turns a crankshaft. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and ultimately motion.

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  1. Phrak

    Could a Valveless Pulse Jet Engine Eliminate the Need for Moving Parts?

    A pulse jet has only one moving part. Nice. But what if it didn't need any moving parts? Stupid idea, right? Check out this stupid idea. They're all over the internet. http://www.youtube.com/watch?v=5U-grFuXZ9U&feature=related"
  2. R

    Why does the J-58 engine inlet spike retract at high speeds on the SR-71?

    I've been reading about the SR-71 and the J58 engine and I'm confused about what I've read about the inlet spike. The spike would start out extended 3 feet but as speed (Mach) went up it would retract, up to 26 inches when at Mach3.2. This confuses me as I thought you'd always want the...
  3. W

    Methode of measuring engine blow-by

    dear all, some literature which I'm read, measuring blow by of engine can be execute use the pipe. not use with pressure gauge. how to measuring and calculating this if we must be use by pipe (not by pressure gauge)...? here is the ilustration...(attach) rgrds =wahyudi.jr=
  4. F

    New 4 stroke engine efficiency

    The new issue of the mechanical efficiency of the new 4 stroke engine.What will have the efficiency of the engine, which increases its volume swept by two times slower rotating crankshaft- piston systems ?? Two times slower or inertia four times smaller. Regards Andrew
  5. J

    Troubleshooting a 2 Stroke Engine: Tips for Starting and Fixing Common Problems

    So I'm back home from uni for afew days during summer. My dad has a little bike 2 stroke engine that won't start, so he has given me the job of attempting to get the little thing to start. The spark plug works. I've taken off the top of the engine block and fitted a fresh seal ontop of the...
  6. G

    Ramjet Engine: How Does It Work at Subsonic Speeds?

    I think i know how the ramjet works at supersonic speeds, because of the shock wave the air particles traveling through the inside of the tube converge and bump into each other and because the air cannot expand it slows down, increasing the pressure, so when the air escapes it expands very...
  7. I

    Calculating rev-gain based on engine specs?

    Is there any way of calculating rev-gain based on engine specs, like bore and stroke? What other variables are involved? Maybe I am thinking of rev-gain in a wrong sense. If the former isn't capable, is it capable to find out the rotating mass of an engine, like the force the engine has to...
  8. F

    Is this powerful rotary engine the future of small-scale power machinery?

    Powerful rotary engine? This is a powerful rotary internal combustion engine. When rotor round one time, engine work six times.My mechanical design aim was to create a power for UAV,MAV, robotics, mini-generators; engine size is very small, can be forged or EDM etching method of mass...
  9. K

    How can fuel injector location and material selection reduce engine problems?

    let use injector as an example Many of the fuel injector problems are centered around the dirty fuel injector. If a fuel injector is dirty i.e. the injector is clogged, the fuel spraying into the engine is going to be restricted. Hence if the fuel injector is dirty you are going to face...
  10. M

    Torque and power produced in an engine

    Homework Statement Why does an IC engine generate about the same maximum torque over a range of engine speeds but the maximum power at only one speed? Homework Equations None. The Attempt at a Solution For max power, the best I can come up with is that since torque does not drop as...
  11. B

    Calculating Work Done by Engine on Railway Wagon

    Homework Statement A railway wagon runs on frictionless rails and is pulled by an engine traveling at 10 ms−1 . The wagon is loaded at constant rate with 1000 kg of coal, dropped vertically from rest for a time of 2 s. What is the work done by the engine to keep the wagon moving at...
  12. P

    SWL to secure engine onto a flatbed trailer

    Hi I'm need to check if the securing arrangements for a load are adequate... Weight of engine and steel transport stand - 7826 kgs secured to a wooden flat bed trailer by 4, 3.2 tonne SWL chain blocks (1 at each corner) maunfacturer states that the securing arrangement must withstand a...
  13. G

    Can I Calculate Engine Speed from Sound Frequency Inside an Airplane?

    I am in the airport right now and I was wondering if there is someway to determine the speed of the aircraft engine from the sound the engine makes inside the plane. I have a audio analysis program and I can determine the frequency of the sound inside the airplane. Is there any way to...
  14. J

    The temperature of the compressed air in a diesel engine

    Hi, Could someone tell me the rough temperature the air gets to under compression, just prior to the diesel being injected and auto igniting? thanks in advance
  15. M

    Note: This is not a real webpage, just a hypothetical title for the content.

    if i were to connect a central axis to the turbine in a small jet engine and down gear it using planetary gearing is there potential for jet a type engine to put out some "real" tourque is there a way i could figure this in foot lbs using the thrust? absolute pressure? thermal efficiency?
  16. F

    A Carnot engine. Got right answers, but I have questions on solution.

    Homework Statement A Carnot engine runs between a high temperature of 500 C and a low temperature of 50 C. The isothermal expansion (upper branch) occurs between a volume of 0.5L and 1.0L. The isothermal contraction (lower branch) occurs between 2.0L and 1.0L. There are 2 moles of gas...
  17. B

    Calculating Work Done by an Engine to Keep Wagon Moving

    Homework Statement A railway wagon runs on frictionless rails and is pulled by an engine traveling at 10 ms−1 . The wagon is loaded at constant rate with 1000 kg of coal, dropped vertically from rest for a time of 2 s. What is the work done by the engine to keep the wagon moving at...
  18. C

    How Does a Heat Engine Lift a Mass Efficiently?

    Homework Statement A heat engine operating between temperatures of 500 K and 300 K is used to lift a 10-kilogram mass vertically at a constant speed of 4 meters per second. (a) Determine the power that the engine must supply to lift the mass. (b) Determine the maximum possible efficiency...
  19. S

    Why do electric motors have full torque at start while IC engines don't?

    how electric motor can have full torque at start? is it because magnetic forces are in phase with turning moment curve of rotor of electric motor. i mean the peak of magnetic forces and peak of turning moment occurs at same time. if we implement this in IC engine does it to can have full torque...
  20. J

    Simpliest way to simulate an IC engine

    Hi Guys, I would like to write some software to teach people to tune internal combustion engines. More specifically, as some of you may know, an engine is controlled by two 2D grids or 'maps' which have engine load on one axis and engine RMP on the other. One map tells the engine how early to...
  21. N

    Carnot engine air conditioner

    A Carnot air conditioner takes energy from the thermal energy of a room at 76°F and transfers it as heat to the outdoors, which is at 96°F. For each joule of electric energy required to operate the air conditioner, how many joules are removed from the room? Attempt at problem 76 + 273 = 349 96...
  22. D

    Coefficient of static friction in a 3D Games Engine

    For a personal project, I am analysing the physics in the Source video game engine and comparing it with real life. I have set up in the engine a platform which increases in inclination from 0 to around 70 degrees. On this platform there are four, equally weighted cubes each with a...
  23. R

    What are dark streaks on the wings of the aircraft near the engine?

    My question is referring to the first picture of the SR-71 on wikipedia. http://en.wikipedia.org/wiki/Sr-71 What are those dark streaks on the wings of the aircraft near the engine?
  24. S

    Does Revving Closer to Peak Power Improve Fuel Efficiency in Motorcycles?

    When I got my motorbike it had a non-standard rear sprocket with two extra teeth. I decided to swap it for a standard one. I expected to get a better overall mpg, but it didn't change noticeably. So... An engine has a red line at 14000 rpm. Peak power is delivered at 12000 rpm. Driving...
  25. W

    Diesel Engine Prob: Formula for Temp at Stages 3 & 4

    how would you find the correct formula for the temp at state 3 and 4. i found it for 1 and 2
  26. V

    What are the Pros and Cons of High Bypass Ratio Jet Engines?

    low bypass ratio engine has low mas flow and high speed, high bypass ratio engine has high mass flow and low average speed. if the high bypass ratio engine has high mass flow and high average speed, what are the advantages and disadvantages of this jet engine?
  27. C

    Using gas engine's residual heat to power a Stirling engine.

    It does not sound bad, does not It??. Using the residual heat it would be possible to power a Stirling engine, producing energy to be stored in the battery. Getting less power from the gas engine, (less time alternator running), less gas used, higher efficiency. How does it sound??
  28. wolram

    Jet Engine Life Span: What to Know

    Does a jet engine have a life span?
  29. J

    Neural network controller for internal combustion engine

    I'm currently doing a project on neural network controller for an internal combustion engine to reduce emissions level. Can anyone assist me in training such models (neural networks)
  30. S

    Why does a car continue to run when the engine is turned off?

    Hello guys, I really don't know much about cars at all. So here is my question 1. If I keep driving and turn off the key the car continues to run? Is this because momentum. Would the car eventually stop due to friction? I mean if spark plug stops working how can the car continue to run...
  31. C

    Spark voltage in a car engine.

    HI, my friends Lets imagine a car engine combustion chamber which is fed with an estequiometric fuel mixture (gasoline+air) with a 1mm plug gap. Is there an aproximate algorithm to solve out what voltage is needed to create a spark, based on gas pressure and temperature?. I don't want...
  32. V

    AT: Calculating Temperature T for Two Carnot Engines in Series

    Homework Statement Two heat engines operating on Carnot cycles are arranged in series. The first engine A receives heat at 927 deg C and rejects heat to a reservoir at a temperature T. The second engine B receives the heat rejected by the first engine, and in turn rejects heat to a reservoir...
  33. R

    Help with Calculating Work Done by a Model Stirling Engine

    Homework Statement I need some help with this problem: A model Stirling engine uses n = 7.44 × 10–3 mol of gas (assumed to be ideal) as a working substance. It operates between a high temperature reservoir at TH= 95.0°C and a low temperature reservoir at Tc = 24.0°C. The volume of its...
  34. P

    Converting engine torque to applied linear force

    Hello, For a given vehicle, I want to use a given chart for engine torque vs. engine speed (or hp vs. engine speed) and convert it to an approximate 'applied linear force' on the car (assuming no wheel slippage). I need a very rough approximation, so I've averaged the engine torque and...
  35. V

    Preventing Engine Overrun: Is Overdrive Transmission Relevant?

    How to prevent engine overrun? Is there any relation between overdrive transmission and engine overrunn? Pl. clarify?
  36. C

    Considerations for acceleration allowance in calculating engine power?

    hello! i have calculated an engine power of a prototype car by calculating the power losses against road gradients, air drag and rolling resistance. i have calculated these losses for max. car speed,lets say 50 kmph. what i need to know is do i need to consider acceleration allowance even when...
  37. D

    How is the force transfered from engine to wheels?

    Hos is the force from a Otto engine (petrol engine) transferred from the engine to the wheels so that the car can move? I would like a short sceintific description, thanks :-)
  38. W

    News Google uncensors its search engine in China

    You can now search for Tienanmen Square Massacre in China. Wonder how long it will last. http://news.bbc.co.uk/2/hi/business/8581393.stm Nice comeback. I love google.
  39. D

    PLease help me - The Petrol engine and the first cars

    I'm working on a really important physics assignment and i am in deperate need of help! I need to find some scientific problems with reference to the first petrol engine and the some of the first cars ever made (1887-1912). I have to present some problems which i am to solve later on. The...
  40. C

    Solving Carnot Heat Engine: Tf = SQRT(TcTh)

    Homework Statement A heat pump takes heat from a hot resevoir and dissipates heat to a cold one. Both resevoirs are equal mass and specific heat capacity. Show that as the heat engine does maximal work the final temp of the resevoirs = Tf = SQRT(TcTh) Homework Equations Qin = Wout +...
  41. C

    Calculation of an engine power

    Hello! Actually i want to find the required power of an a single cylinder air cooled 4 stroke OHV engine. i have calculated three power losses, power loss against road gradient (Pg), rolling resistance (Pr) and drag (Pd) using the following formulae: Pg=M*g*v*grad=1.095 hp M(mass of the...
  42. B

    Diesel internal combustion engine converted to hydrogen?

    Okay, so I've found this site (http://www.spiritofmaat.com/archive/feb2/carplans_doc.htm) and it claims to have a reliable method to convert a diesel engine to run off of hydrogen. Now, my question is is this actually feasible in the method they've described? I've asked two other sources and so...
  43. S

    Intake Temperature for a 40.2% Efficient Carnot Engine

    Homework Statement The exhaust temperature of a Carnot heat engine is 401◦ C. What is the intake temperature if the efficiency of the engine is 40.2 %? Answer in units of ◦ C. Homework Equations e = 1 - Tc/Th (all in Kelvin) The Attempt at a Solution 0.402 = 1 - Tc/ (401+273) = 1...
  44. H

    What is the average mechanical power output of the engine?

    Homework Statement A car with mass 1000 kg accelerates from 0 m/s to 40 m/s in 10.0 s. Ignoring air resistance. The engine has a 22% efficiency, which means that 22% of the thermal energy released by the burning gasoline is converted into mechanical energy. a) What is the average...
  45. G

    What Is the Maximum Work a Heat Engine Can Perform in a Cycle?

    Homework Statement 21. A heat engine operates in a cycle between temperatures 700 K and 400 K. The heat input to the engine during each cycle is 2800 J. What is the maximum possible work done by the engine in each cycle? (A) 1200 J (B) 1600 J (C) 2100 J (D) 2800 J (E) 4400 J I...
  46. F

    Who can heip me manufacture my engine

    I have designed a powerful rotary internal combustion engine. When rotor round one time,engine work six times. It can be used UAV power or portable generator or soldier power.for it is a high speed machine ,we can pay few attention about the seal problem.you know,when the speed of the engine is...
  47. F

    Is a High Horsepower, Lightweight Diesel Engine Possible for a Race Truck?

    Hey, I am working on a project and yahoo answers hasn't been much help. I am building a light weight race truck and I was hoping someone in here had heard of a high horse power diesel engine that wasn't heavier then the rest of the truck :)
  48. C

    What is the Efficiency of a Carnot Engine?

    Homework Statement http://img291.imageshack.us/img291/7786/effx.jpg Homework Equations e=1-1/(V1/V2)^(gamma-1) The Attempt at a Solution This is a practice test where he gives the solutions, as you can see the first thing he asks for is the efficiency, and lists the answer as...
  49. B

    Carnot Engine Work Output w/Monatomic Gas: 288K to 497K

    Homework Statement A Carnot engine working with a monatomic gas operating between two temps, 288K and 497K. The engine performs 800 J of net work. Homework Equations Q = nRT ln (V final/V initial) The Attempt at a Solution I don't have enough info for the above equation. I...
  50. J

    Jet Engine Sound Intensity Calculation with Absorption Effects

    Homework Statement I=\frac{p_{ave}}{4\pi r^{2}} is derived on the assumption that the transmitting medium does not absorb energy. It is known that the absorption of sound in dry results in a decrease in energy of about 8 dB/km. The intensity of sound at a distance of 120 m from a jet engine is...
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