Engines Definition and 291 Threads

I saw a video recently describing the lift in terms of pressure. It stated that the Coanda's effect is important. That is the tendency of a fluid jet to flow a curved path. It stated that there is high pressure above the top of an air foil and low pressure below so the air drops or gets...

I was interested in whether it might be possible to incorporate a steam expansion power stroke into a two stroke or a rotary engine. The difference would be that unlike the convention Crower six stroke cycle there would be compressed air in the combustion chamber, without some sort of valve...

I have heard that Stirling engines are not in wide use because they have a low power-weight ratio. Why is this? It would seem to me that the Beta type stirling engine (with 1 cylinder) would be very efficient because it only has like 3 major moving parts...flywheel crankshaft and piston and...

Hi, i am a 2nd year B.E student in India,and a new user to this site(sorry for any mistakes :) ) .My question is i want to do research that primarily concerns these 2 areas viz.Wireless energy transfer, and future space engines(starwhisps,solar sails,etc),is there any way to achieve my dream,i...

Dear engineering community: For many years now I have wondered why our internal combustion engines have not been adapted for methane in place of the various forms of petroleum products we currently use. Why? (1) Because we have a gargantuan ever-renewing source of methane in human garbage...

A HUGE topic of conversation on many car forums, I thought I would bring it here. Many cars have chrome tin in the engine compartments to make them look flashy. However, for decades now, people say the chrome reflects the heat back onto the engine block and to paint the engine compartment black...

Homework Statement A block of radioactive material is ti be used as a power source for a deep space probe which may be treated ideally as a single Carnot engine. Radioactive decay generates heat in the block at a rate Pin = dQin/dt and heat is extracted from the block to operate the probe at a...

Why do we use water for steam engines? Why not something else? So, I have a question, or maybe it is an idea that i would like to share. So, sure, there are many finer points to the engineering of a steam turbine to make them work efficiently, and no doubt the designs have improved much since...

My question is: according to Carnot cycle, the maximum efficiency of a heat engine is given by 1 - T2/T1, where T2 is the temperature of the cold source and T1 the temperature of the hot source. So, accordingly, as higher T2 is for a same T1, lowest is the efficiency of the engine. But, the...

Homework Statement Two identical tanks of water are at absolute temperatures ##T_A## and ##T_B## respectively, where ##T_{A} > T_{B}##. The tanks each have a heat capacity ##C##, and they are thermally isolated from their environment. Suppose that a heat engine is installed in contact with the...

Homework Statement I have a question regarding heat engines that cropped up whilst I was doing a practice question. I will summarise the results I obtained for the previous parts of the question so as to save your time. The highlighted parts of the image are where I am having some issues. I...

I have read ( excuse me but i don't remember the reference) that a diesel engine, contrary to an engine that works on the otto cycle, is a " steady torque" engine meaning that torque doesn't change with revolutions. Could someone explain me the reason? ( in case that this statement is true )...

In a perfect, ideal world with constant specific heats the thermal efficiency of an otto cycle is dependent on its pressure ratio and a diesel cycle is dependent on its pressure ratio and cut off ratio. But since in the real world the equations with these terms do not hold since specific heats...

I have a some problem about marine propulsion. Assume the 4 engine-fast gunboat is moved by forward two engines. The boat get 10 knots. Then if other Aft two engines operate gradually. You know the boat doesn't get 20 knots speed. What are the reason for that? Explain theoretically? Thanks for...

Noting that ice expands by about 9%, why isn't it possible ot build a heat engine from this natural process?

I tried to calculate the efficiency of a engine using the formula : Efficiency = (Net Work Done) / (Heat absorbed) And then I tried to calculate the efficiency of respective Carnot engine by two ways : 1) Efficiency = (Net Work Done) / (Heat absorbed) 2) Efficiency = 1 - (Temperature Lowest /...

are engines in our cars follow the carnot cycle or they work differently

The main result of thermodynamics is that if you have a place that is hot and another place that is colder, you can operate a heat engine by absorbing heat from the hot place and dumping it in the cold place, extracting some useful work in the process. It gives you a way to calculate the...

This is quite a serious question, I was asked to write few words about a similar game (not officially published yet) and I started to wonder what were the earlier programs of this type. This is partly engineering and partly physics problem. Many computer games use some kind of physics engines...

I'm stuck on a question, part d below: My attempt: I reckon that T4 = T3 and T2 = T1, otherwise I don't know how else you can get T4 and T2...? Once I got first part of d, I reckon I could do efficiency using part c that I derived. I don't see where I'm supposed to use compression ratios...

Hi I was wondering why are model rocket engines disposable after one use? Is it because it is more economically feasible to buy a new model rocket engine than to repair a used one because the process of using a model rocket engine always ruins it? Also, if it is the case that model rocket...

Hi everyone! I am trying to make a presentation concerning up to date internal combustion engines for different applications (light duty/passenger cars, heavy duty, marine/low rpm, aviation etc). I don't need any charts just sheer numbers of power, capacity, weight, engine dimensions...

A rocket fires two engines simultaneously. One produces a thrust of 655N directly forward while the other gives a thrust of 508N at an angle 34.0∘ above the forward direction 1.Find the magnitude of the resultant force which these engines exert on the rocket. 2.Find the deviation of the...

I am studying to be a pilot and something I've read in the book confuses me. It is that Vertical Takeoff and Landing (VTOL) engines need to be heaver than their corresponding traditional takeoff/landing counterparts. Wikipedia says the same thing here. I am going to interpret "larger" and...

(I'm not sure I put this thread in the right sub-forum) If we need to operate a nuclear-powered heat engine in space to run a generator, meaning it can only be cooled by radiation, what kind of system should we go for, if we want the power per unit mass ratio to be as high as possible? I've...

Homework Statement At a steam power plant, steam engines work in pairs, the heat output of the first one being the approximate heat input of the second. The operating temperatures of the first are 718∘C and 427∘C, and of the second 419∘C and 270∘C. A) If the heat of combustion of coal is...

Hello all, Most engines today in passenger cars are made out of aluminum instead of iron. I am confused about the fact that aluminum is lighter than cast iron and warps easier under extreme temperatures. How do they stop this warping from occurring?

When dealing with power losses from engine to drive wheel(s) i ignored losses other than straight friction, can cooling and alternator losses be taken as roughly a percentage of the cars engine power ? Thanks Dean

Greetings, Here is my thought process on the carnot cycle, regarding heat pumps and engines. I'd much appreciate it if you can clear up any misconceptions and answer my question at the very end. So my book states that there is no change in internal energy in a heat engine, but neither confirm...

Hi all, I have a random query that I suspect you guys will able to help me with on reciprocating engines (ala like steam engines rather than petrol motors). In the classic steam engines, obviously boiling water in a Pressure vessel and fed through a reciprocating engine is able to produce...

Can you explain me why search engines sometimes can not find existing entries. I can find them in the site, I can see them but Google and Bing can not find them. Best Regards.

im looking for engines that are known for being extremely high effiency. im not just talking about high efficency consumer engines, but highest records, etc also, consumer level is nice as well, but please tell me that they are consumer level if you do list them. please list electric...

Is is possible to have 2 different engines with all the following criterion? 1) Are reversible 2) Work differently (different cycles) 3) At the same working temepratures have different efficiencies. E.g. Working temperatures 100K and 50K. Engine 1: Carnot's Efficiency - 50%...

I'm looking into buying an E34 530i with a smaller 3 liter V8 compared the the 540 4.4 liter V8. A lot of people online say buying a 530 is pointless when you can get the same car with more displacement and more power. I think that's ridiculous since displacement is only 1 of many ways to make...

I've noticed that engines have gotten very complicated, thus more complicated in the past few years into squeeze more power and efficiency out of them, Ford's ecoboost in particular. I was wondering if it would be just as efficient to equip FWD cars with a small, very undersquare inline sixes...

Hi all, I've got a past paper question that goes something like this: An aeroplane has four engines. During a certain journey, each engine fails with a probability of 0.1, independantly of the others. The aeroplane can fly when at least two engines are working. Calculate: A) The...

this is thing I'm thinking about for few years. why standard passenger car diesel engines are so limited in engine capacities range? if we take petrol engines, there are anything from 1.0 liter to 3.0l Inline 4 cylinders, 2.0-4.0l 6 cylinders (or even bigger in USA), 4-7l V8 etc. but take...

Not sure if this should be posted in the general physics forums or in the hw/coursework section. I'm in my second semester of general physics and have to do a class project. For my project I built an alpha type Stirling engine. In the paper I need to write I need to explain how it works using...

Hi guys, I'm an incoming engineering student at Ohio State and am really fascinated with what goes on under the hood of my car. I've done about 20 minutes of fruitless light searching on how engines work and wanted to know if there are any classic textbooks or resources on this topic. Also, I'd...

Dear Physics People, I am a religion teacher with a background in philosophy and theology. I haven't taken a physics or calculus in some years, so there is a lot of information that I'm missing in my head. So here's the deal. Airlines spend millions of dollars on fuel a day (around $32...

a friend and i have been discussing taking what we know (mostly what i know) in the field of mechanical engineering and designing and building a car.. it will be my car, but he's willing to help with it the body style of this car might look something like a cross between a corvette/viper and...

Hey Guys needed some advice related to Turbocharging of natural gas engines. I'm working on turbocharging of gas engine for the first time and was trying to do some research on the same before jumping into the nitty gritty stuff. I Do not have much experience working with turbochargers. Turbo...

what will be the temperature and pressure at the exhaust of IC engine?

Homework Statement a heat engine draws 200J of heat from the hot reservoir at 400K produces 110J of useful work and dumps 90J into the cold reservoir at 200K could this engine be built why or why not? Homework Equations PV=NkbT The Attempt at a Solution Not Sure on how I would set...

Hello, Homework Statement Engine A receives four times more input heat, produces six times more work, and rejects three times more heat than engine B. Find the efficiency of (a) engine A and (b) engine B. Homework Equations e = |W|/|QH| e = 1 - |Qc|/|QH| The Attempt at a...

barring a few exceptions i read that it is because they aren't effecient at small scale. can someone elaborate on that? also, would even smaller turbines need some time to start up?

Thank you for reading. Turbine engines have been used earlier by Chrysler. If throttle response is a reason they aren't prevalent there are many ways to reduce it. If I am not wrong, the compressor can have variable geometry vanes(similar to VGTs) and thereby reduce lag. I learned that it...

Lithium Hydride contains more hydrogen per unit volume than liquid hydrogen does, so what is stopping us from developing a Lithium Hydride storage solution to supply hydrogen to a vehicle's engine? The reactivity of the substance would throw up some substantial challenges, but compared to...

Anyone have any good resources/how-tos on building miniature (or not so mini) stirling engines? They seem pretty simple to make, and the coke can ones are pretty cool.

Why are the engines of sports cars so loud? I thought a good engine should be very quiet because all the work done must go to moving the car forward. If they produce so many noises, isn't that just wasting fuel/power? Is the production of big sounds a must for the working of the engines, or...