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. S

    [Thermodynamics] Two bodies exchanging heat through a Carnot engine

    Homework Statement It's basically the classic problem I've seen here a lot. There are two bodies, both with equal heat capacity (C_P), one at temperature T_1 and the other at T_2. They exchange heat using an infinitesimal-reversible Carnot Engine, which will work until thermal equilibrium is...
  2. H

    How is this heat engine formula derived?

    Homework Statement there is a question solution i am looking at, and it goes from TH(Vb)^(y-1) = TH(Vc)^(y-1) and it appears to be rewritten as Vc=Va(TH/TC)^(1/(y-1)) Can anyone please explain this? thanks
  3. W

    Relating speed and engine horsepower of a ship to water resistance

    Homework Statement The aircraft carrier John F. Kennedy has mass 7.4*10^7kg. When its engines are developing their full power of 280000 hp, the John F. Kennedy travels at its top speed of 35 knots. If 70% of the power output of the engines is applied to pushing the ship through the water, what...
  4. S

    Automotive Heat/energy balance for a high power petrol engine

    Hi, first post newbie here, so go easy please:smile: I'm trying to get a grip on the understanding of a car cooling system for a friends race car. It seems the more I look into it the more questions I'm left with. For this post I would like to clarify the coolant side, leaving the air side...
  5. K

    Automotive Engine oil flow/pressure restriction

    Hello everyone, My first post was deleted by admin. Anyways, the question is back for those who have not read it. I am installing a turbo system onto a motorcycle with an oil pressure range far too low for the turbo. I have develloped a restricter that has boosted the pressures to where they...
  6. dbmorpher

    Solar Driven low Resource Consuption Steam Engine Materials

    Hi I'm dbmorpher For my local History fair I am basing my report on the Indutrial Evolution and it's Inventions namely the Steam Engine. I wanted to know if there was an easy way to make a steam engine that was or had... Low cost parts No fuel such as coal or wood No need for complicated...
  7. U

    Front engine dragsters: where science met art.

    Here's a neat sight I found on Faceplant. Look for the photos of the "Original RAMCHARGERS". These guys were engineers at Chrysler that formed a car club called "The RAMCHARGERS" and changed drag racing history. They were a combination of enthusiastic young hands on engineers and car club...
  8. C

    Calculate the work done in an external combustion engine

    Hi Not a homework question, just a fool tinkering... I have been messing around with the concepts of a stirling engine, and have been looking at other engines which do not use an explosive mixture (petrol etc) as their heat source. I have to say I am having trouble getting my head...
  9. K

    Automotive Why does CI engine performance change with load and speed?

    why the mechanical efficiency and brake thermal efficiency curve increases as load increases and reaches a maximum value and then again decreases( in contand speed test)
  10. Low-Q

    Gerotor style turbine , or gasoline engine

    Gerotor style "turbine", or gasoline engine Hi, I have read a bit about gerotor style pumps. It seems to me that there is only two rotating, balanced parts. If water pressure can enter on one side, the water have no where else to go than through the gerotor before it can continue. The...
  11. R

    Using a motorbike engine to rotate a generator

    Hi, I am thinking to use a 100c 8hp motorbike engine to rotate a 2KW generator which must be turned at 1500rpm. I thought of setting the bike engine to 2200rpm on no load so that when I put the generator on full load, the rpm hopefully will not go under 1500rpm. So what I want to know is, if...
  12. D

    Readily-available radioisotope heat source for a Stirling engine?

    Hi folks...I'm new here, please go easy on me, it's been quite a long time since college physics! :-) I need a feasible and readily available heat source for a Stirling cycle engine. (It's a type of engine that runs off of hot air...google it and you'll see plenty of examples.) Is there a...
  13. S

    Basic thermo question: heat engine efficiency

    Is it strictly true that an engine will be more efficient if operating in a hotter environment... e.g. your car is more efficient in the summer than the winter? Just going through thermo 1, not a HW question, but it just seems to be true to me because the simple Newton's law of cooling says...
  14. A

    Design a Stirling Engine: Gamma vs. Beta

    I am thinking of building a Stirling engine and am debating between a gamma type and beta type. Any advice on which type I should go for, and what the advantages/disadvantages to each is? Thanks
  15. D

    Aircraft engine horsepower display

    I am trying to design an on-board horsepower display for an experimental aircraft. The parameters that determine engine power are RPM, manifold pressure, altitude, temperature and mixture. Each of these parameters is currently monitored and displayed individually in the airplane and the...
  16. A

    Why Engine Choke Helps an Engine Start on Cold Days

    Why does the choke help an engine start when it is cold? I know that the choke restricts the air flow and thus makes the mixture of air/gas entering the engine more concentrated with fuel, but why would that make it easier for the engine to start on a cold day? Shouldn't the engine be easiest to...
  17. C

    How to find power of an engine in UCM?

    Homework Statement A plane of mass 1930kg, driven by a pilot of mass 70kg moves at a constant speed of 200 metres/sec describing a vertical circular trajectory, so that in the top of the circle the pilot is 'upside down'. Find the minimun power of the engine so that they can move from the...
  18. N

    Does Increasing ICE Engine Efficiency Lower Exhaust Temperatures Proportionally?

    So the current estimate is that an ICE engine is about 20%. If we were able to increase the efficiency of a given engine, would that result in a proportional decrease in exhaust temperatures? (Given that driveline loss to friction is constant)
  19. C

    Wing Mounted Engine Position

    I've noticed on a/c with only two wing mounted engines that they tend to be closer to the fuselage than the wing tip. There must be some reason for this, and so I guess my question is why? Does having them farther out on the wing create too much stress? I would assume if a/c manufacturers could...
  20. V

    Work of a car's engine as it moves up a slope

    Homework Statement A car of mass 900 kg accelerates up a slope. The velocity of the car at the bottom of the slope is 5 m/s. By the time the car reaches the top of the slope, its velocity is 15 m/s. The slope is 8m high from the ground and has a length (radius - angled length - not base) of...
  21. T

    Heat engine- calculating minimum energy per cycle from hot reservoir

    Homework Statement A heat engine operating between freezing and boling points of water takes 20 cycles to raise a mass of 1000kg through a height of 3m. Calculate the minimum energy per cycle that must be extracted from the hot reservoir in order to achieve this. Homework Equations...
  22. S

    Needed: Material for Engine Compartment bolt on.

    Dear Physics Forums members, I humbly ask your guidance on a project I've just started :blushing:. I need to find a material that can be fabricated for a device that is to be placed in a car engine compartment. Forged, cast or cut, it must withstand the heat of the engine (although it will...
  23. C

    Dozer Engine Torque and Horsepower Calculations

    I have been given a project at work to find the number of dozers needed to push a certain volume of material in a certain amount of time. My issue comes with the actual horsepower of the dozers. We run D10T, D11R, D11R CD, and D11T Cat "track-type tractors". So from what I am thinking, I want to...
  24. S

    What is the efficiency of a Carnot engine and the effectiveness of a heat pump?

    Homework Statement A Carnot engine uses hot and cold reservoirs that have temperatures of 1684 and 842 K, respectively. The input heat for this engine is |QH|. The work delivered by the engine is used to operate a Carnot heat pump. The pump removes heat from the 842-K reservoir and puts it...
  25. J

    Automotive Can a diesel engine run on gasoline?

    I haven't read or heard about anywhere, but is it possible to run a diesel engine on gasoline/petrol?
  26. J

    Can a high-compression engine run on low octane fuel without knocking?

    Can a direct injection petrol engine of compression ratio 13:1, or around that much, be designed to run on fuel of low octane number, say about 87, without knocking? I think it is possible if the fuel is injected just at the end of the compression stroke like in a diesel engine. Is there such an...
  27. C

    Rotary atkinson cycle engine

    http://white-smoke.wetpaint.com/page/Rotary+Engine does anyone know of this engine being used in production?
  28. T

    Question about the Carnot engine

    I was reading about the Carnot engine, and I stumbled upon this forumla: Carnot efficiency = 1 - (QH-QL)/QH = 1 - (TH-TL)/TH Where QH is the heat input, QL is the heat output, TH is the input temperature, TL is the output temperature. The book says that TH is proportional to QH, and TL...
  29. P

    Turbine Engine Questions: Squealer Tips & Classified Weights?

    I recently saw the terms "Squealer Tips" and "Classified Weights" in a text about turbine blades in an article on the Pratt & Whitney PT6A turbo-prop engine. Can anyone explain what is meant by these two terms? What are they and what do they "do"?
  30. M

    Compressing He for Weather Balloon Engine

    Hi, I have a weather balloon and I would filled it with He and attach some weight and I would release He as balloon climbs and it will eventually stops at some altitude. So now I wanted compressor to acts like an engine because air is thin at 20-30km and I would put solar panels to provide...
  31. C

    Formula for working out power produced by petrol being burnt in an engine

    Iam not looking for the answer, I would just like to pointed in the right direction with the formula which would help me work this out. Its been a number of years since I have had to do this. (AN EXTREMELY MATURE STUDENT) Thank you If the fuel consumption of a car, traveling at a steady 60...
  32. J

    I.C. Engine Question. Solve for: Mean Effective Pressure & Volumetric Efficiency

    Hello all. I am new to the forums. I am having trouble solving a couple of questions. Maybe some of you can help me out. Thanks in advance! Homework Statement Number of cylinders 4 Stroke cycle 4 running at 4400 rpm Volume...
  33. J

    What kind of engine would you use for this project

    Hi I'm currently working on a logistic robot for my final project in Mechanical Engineering. My vision is to design something similar in features to this robot: http://www.its-eng.com/logistic-robot I would really like to join military vehicle manufacturers industry so its really important as...
  34. F

    Calculating the power of a car engine

    Homework Statement The driving power of an engine is, say 30 kN. the car drives for 5 seconds with an acceleration of 10 m/s2. The initial velocity is 0 m/s. 1) What does the minimum engine power need to be for this? 2) What is the power of the engine at the end of the acceleration...
  35. D

    What is the optimal torque angle for hardened head studs in a vehicle?

    Hi, can't believe I haven't discovered this forum until now - I would post in an introductions section, however I couldn't find one! This question is loosely based around mechanical engineering, however may be applied to automotive, so apologies for posting in the wrong section. I have had a...
  36. W

    RPG physics engine or building everything together

    I am doing attemp to build rpg with realistic world and AI. So what i need to simulate the persons are moving from input so them not there will be anatomy simulation. My list: 1.full range of collision types absolutely elastic and inelastic and things between them 2.dynamics in air and...
  37. H

    Heat Engine Cycle: Answers to (i), (ii) & (iii)

    Does anyone can help me in this question? Two reversible heat engines operate in series between a source at 600C and a sink at 30C. If the engines have equal efficiencies and the first rejects 400 kJ to the second, calculate: (i) the temperature at which heat is supplied to the second...
  38. M

    Calculating the force on a Crankshaft in a Steam Engine

    Given that I have a steam engine, and now its size, the size of the piston, the length of its stroke and the force acting on the piston at certain points, I need to calculate the force on the crankshaft. Now, I now that Fx should be the same where the piston meets the crank, and we can ignore...
  39. Z

    Thermal dynamics - Metals on Engine Components

    I have some car engine related questions, but basically just physics. -Do different specific heat capacities have anything to do with how certain materials resist heat? I know that on some engine compartments there is gold wrapping because it resists heat best, but it has a low specific...
  40. G

    What will be the pressure inside a small hydrogen peroxide rocket engine?

    Hello, I am designing a small hydrogen peroxide rocket engine. Hydrogen peroxide will be pumped into a combustion chamber where there will be a catalyst (manganese dioxide in this case) that will convert the peroxide into steam and oxygen. These byproducts will then exit through a nozzle. I am...
  41. E

    Automotive Is This Engine Design the Most Efficient Yet?

    Hi i would like to post for discussion my design of a new type internal combustion engine Please post your comments.The following information is to explain the description and operation. In drawing #1 The engine has three heavy pistons all attached together; two small and one large one in...
  42. Filip Larsen

    Live! Witness TM65 Liquid Propellant Rocket Engine Testing

    A livestream video feed from the event has started and can be accessed via the CS homepage [1] or the corresponding blog on Wired [2]. Some background information about CS can be found on [3] together with a (very) short description on the TM65 [4]. [1] http://www.copenhagensuborbitals.com/ [2]...
  43. E

    Problems finding Volumetric Efficiency

    1. The problem DIESEL IC ENGINE We were given a excel sheet, with RPM, Torque, Power, Bmep, Fuel mass flow rate, Airmass SFC, Engine Air inlet and Exhaust temp. The engine capacity is 2.2litre 4 stroke. Fuel specifications: 50 Cetane (0.05% Sulphur) Coolant = Fresh water with 45% glycol mix...
  44. D

    Heat Engine Carnot Efficiency question

    Homework Statement A heat engine has a carnot efficiency of 0.11. How much internal energy does this engine use in order to do 5.1 x 10^4 joules of work? How much heat does this engine give off/exhaust?Homework Equations (change in)U=Q-W W=(change in)E
  45. K

    Automotive What parameters are kept constant during an IC engine performance test?

    Hi, I came across an engine performance graph as attached. I have basically two questions looking at that: 1.To do any engine testing we keep some parameter constant - May be throttle position or applied load (torque) or speed or power. What is kept constant for this test? 2.In the...
  46. G

    Maximum efficiency of an engine taking heat from two hot reservoirs

    Homework Statement A heat engine is taking identical amounts of heat from two hot reservoirs at temperatures ##T_{H1}, T_{H2} ## doing work and then heat to a cold reservoir ##T_C ## What is the maximum efficiency of this heat engine? Homework Equations For a Carnot cyle it is ## \eta = 1 -...
  47. E

    What kind of engine do I need to build a flying board ?

    What kind of engine do I need to build a "flying board"? Hi there, I'm pretty much new here and I've been making lots of research about engines, ion engines, turbines etc. But I still don't understand. I want to build a steel board, since I have the facility to work with any kind of metal...
  48. G

    Build a Simple Steam Engine for Under Rs. 10

    Hello everyone this is my first steam engine made using very simple parts like cardboard, disposable syringe, straw, pen end caps and bicycle spokes. How much economical can you make your engine? Here it is costs only about Rs.10. Blowed air through mouth that's why produces lower rpm use...
  49. Ryan_m_b

    What is the progress of the Sabre engine development for the Skylon spaceplane?

    Today sees a key test in the development of the SABRE engine for the Skylon Spaceplane project: http://www.bbc.co.uk/news/science-environment-17864782 What do members think of the prospect of this project? Seems to me that like all promising space ideas it would be great if it could get the...
  50. C

    Ideal Heat Engine: Input Temp Change, Exhaust Temp Change?

    An ideal heat engine operates with an input temperature of 327C and an exhaust temperature of 27C. If the input temperature is lowered to 227C, by how much must be the exhaust temperature be lowered to maintain the same eciency?Im using η= 1-(tc/th) that works out to 1-(300k/600k) = 0.5 then...
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