Engine Definition and 999 Threads

We know efficiency (η) = Woutput/Winput Now in any cycle, for instance, the Otto cycle, let the total work output be WO, total heat added be WH & the total work done on the gas to compress it be WC. Then, will efficiency be equal to (η) = (WO-WC)/WH ? Or will it be equal to (η) = WO/(WH+WC) ?

If this is a valid enough definition of a heat engine: All heat engines transfer heat energy from higher to lower temperatures, and do work in the process. ... then is the human body a heat engine?

I am tutoring a student, and this question was given to her. I believe it is not clearly stated and wanted your opinion. I hope this is the best forum for this. 1. Homework Statement What is the minimum wattage required to accelerate a car of mass m (don't remember the value) from 0 to 28 m/s...

Help me please:) (1) An idealized engine with constant torque curve means constant acceleration. So for example if there is no air resistance and no frictions and car is on fixed gear and at 3000Rpm it produces 50Hp so at 6000Rpm will produce 100Hp. So he doubles the speed , doubles power and...

A 4-cyilinder engine with a staggering 432,000 miles on it is actually in surprising good condition.

Homework Statement There is a 1 kg (52x52x52mm) square block attached to a 200 mm long (d = 8 mm, weight = 0.03 kg) rod what is connected to an electric motor. The setup is vertical and needs to achieve about 90 rpm. So, the 1 kg square block will circle on the outer rim, connected to the...

Homework Statement Homework Equations a = v/t p=mv(?) The Attempt at a Solution If an engine is turned on, that means that the ships are accelerating since the engine pushes back on air with a force and air pushes back to propel the ships forward, so I thought (A) would be the answer, even...

In deriving the Carnot Efficiency, the assumption is made that theoretically most efficient engine will generate no net entropy, meaning that the entropy that enters the system during heat absorption must equal the entropy that leaves the engine during heat rejection. Why is the case? Why would...

Homework Statement The problem is "A multicylinder gasoline engine in an airplane, operating at 2.40 10^3 rev/min, takes in energy 7.98 10^3 J and exhausts 4.50 10^3 J for each revolution of the crankshaft." and it wants me to find the liters of fuel consumed in 1 hr of operation if the heat...

If the right wing right engine suddenly fails.which of the two rudders and how must be moved so that airplane maintains its attitude and flies straight (assuming the plane is on air not landing)

What would the theoretical maximum possible speed be for a platform on a horizontal air-bearing (friction-less), if the only propulsion was a spring powered machine gun with unlimited steel balls? The balls go one way, the platform moves proportionally in the opposite direction. Ignore inertia...

I recently saw the video of the frog being levitated with a big magnet. Would it be possible to flip the magnet over and use it to levitate a vehicle? How much energy would it take to levitate, say, a 1000kg vehicle above a dry lakebed?

Hi All, The ECU on my motor bike allows you to select different amounts of engine braking in it's various riding modes. I imagine that the ECU just opens up the throttle bodies a little so that at closed throttle the engine still delivers a bit of torque. Doing this will increase the idle speed...

Homework Statement The emission of radiation from the Sun’s disc is observed to peak at 0.5 μm wave- length and that from the Moon’s disc at 10.0μm. A heat engine to power a Moon base is to be constructed using radiation collected from the Sun. What is the maximum theoretical efficiency of such...

Hi folks! A while ago, we discussed a real-time simulation of an oil cycle within a combustion engine. Back then I was focusing on volume flow and pressure and you were incredibly helpful in coming up with the required formulas, so thank you again for your help! I'm now moving to the next...

Hello, In mechanics, power is defined as the rate at which energy is either produced or consumer: ##\frac {E}{t}##. A different but equivalent definition is ##P= F v##. In the rotational world, we talk about rotational power and the expression becomes $$P= \tau {\omega}$$ where ##\tau## is...

The engine was used to propel a small home made air craft. It worked very well while it taxied away and went airborne, then at a certain altitude it stopped abruptly then came crashing down. Why? And what simple engine design can sustain the air craft?

If you took a 400 horsepower gasoline pickup engine and a 400 horse power semi engine and hook them up to a transmission so that they had the same output rpm while each engine is at their peak horsepower rpm would they be able to pull the same load fairly similar?

A high-performance diesel engine explodes into pieces while being run on a dyno test.

"A Carnot engine operates using a heat source at 500 °C, and a heat sink at room temperature (20 °C). Suppose that as a heat source, you use the combustion of 100 cubic feet of natural gas at room temperature and pressure (e.g. in a fuel cell of some kind). Under ideal conditions, what is the...

Hello! I'm trying to write a 2D program that uses simple physics. I was wondering what would be the best 2D physics engine to use in my case, and if it even matter what engine I choose. I also want my simulation to run in real time, so at least 30 fps on a decent home computer. I prefer a fast...

Hi All, I had to reinstall my SQL Server and I a having trouble finding the database engine which is the local host. Please see screenshots. Any ideas? Thanks.

Can I use a Clutch Plate assembly along with drive shaft to connect Engine & dynamometer? I am facing an issue where in CRDi engine, at a position of accelerator pedal RPM is increasing from 1300 to 2000 without any change in accelerator pedal position. And a lot of vibrations takes place at...

Hello Physics Forums! After almost a year of haggling and research, I think I have successfully made a engine simulation spreadsheet! :oldbiggrin: I have simulated the Nissan KA24DE Engine with two different cam profiles: As far as I'm concerned, there is still a lot of work to be done...

Hello Physics Forum Users! I have an annoying situation with the Finite Heat Release Equation used to simulate combustion and expansion processes in an internal combustion engine. The equation is as follows: Nomenclature: P = Cylinder Pressure (kPa) θ = Crank Angle (Deg) k = Specific Heat...

Does anyone know of a source, on the Internet preferably, for component inertial data for a real IC engine? In particular, what I'd like to obtain (for some real engine, any engine) are these items: 1. Piston weight (including wrist pin) 2. Cylinder bore dimension 3. Connecting rod length...

Trying to remember some basics. I know the thrust of a jet engine. I'm thinking about equivalent HP. I can establish HP at a given speed, but what about while accelerating? I will display my ignorance here :( Power for static, non accelerating flight: Power = [Thrust x Airspeed] Thrust...

Hi, i’m learning about the thermal efficiency of a diesel cycle at university and I'm trying to understand the equation. The first law of thermodynamics states Wnet + Qnet = 0, but one of the attachments below says Qnet - Wnet = 0 and I don't understand how this is the case. Also, for process...

Homework Statement I am having difficulty understanding the conversion between power and rotation at the engine and at the wheel. Can you please state which parts are right and wrong, and why please as I think I've spent that long on researching I've confused myself with too much information...

Homework Statement Homework EquationsThe Attempt at a SolutionTaking the engine to be a Carnot engine, ## \eta = \frac { T_h – T_c } {T_h} = \frac { W} {Q_h} ## ...(1) ## Q_h = C(T_h – T_f) ...(2) \\ Q_c = C(T_f – T_c) ...(3) \\ W = Q_h – Q_c = C(T_h + T_c – 2 T_f) ## ...(4)Solving...

Just trying to understand how efficient RDE's are thermodynamically based on a 2016 paper from Bulat and Volkov titled "Detonation Jet Engine. Part 1 – Thermodynamic Cycle" and a 2013 paper by Nordeen et. al. titled "Thermodynamic Model of a Rotating Detonation Engine": Based on these papers...

Homework Statement Homework EquationsThe Attempt at a Solution P = 1500 * [area occupied by the cycle = ## 4 p_0 V_0 ## ] /60 = 15 kW Is this correct?

Most engine specifications I have found only provide the engine mass flow rate for take-off setting. For example, the V2500 has a mass flow rate of 354.25 kg/s. How does the flow rate vary through different power settings? For example, if the engine is on idle, will the mass flow rate be 0...

Greetings! I did the famous "Mass Lifter Heat Engine" experiment in which a mass is put at the top of a piston enclosed within a cylinder. The cylinder is connected to an aluminium canister of air and the air inside this canister expands and contracts the piston with thermal contact. We had 2...

I have been working on a rocket engine and I have cad models and everything and I am getting ready to build it. Then, I was running over the numbers one more time and I realized that the thrust I was getting was completely different from what I should have been getting. The big problem is the...

I am looking to calculate the area around the engine where, if an object enters this area, it would be "ingested" by the engine (subsonic flight). In other words, I am looking to draw the shape around the engine, where the air within that shape is disturbed air (being ingested by the engine)...

Hello , I am thinking to work on a RC aircraft ( Airplane ) that can load a small supply of Medical Firstaid in small range. So I need to make it fast and stable. So I'm thinking to use a small Turbo-jet engine in it which will be home-made. Please suggest me -- (1) Is that makes any sense ...

I have some questions regarding my observations of a misfiring bi-fuel vehicle (CNG and Gasoline). 1. For same misfire rates, in Gasoline mode, the exhaust catalyst temperature is higher than the in CNG mode. 2. For lower misfire rates, in CNG, the temperature is higher than with higher...

I am trying to figure out the power required to lift a hover bike that would have four propellers and would weigh around 400-500 kg. how can i select an engine and find the required shaft power, rpm, engine cc and thrust required.

What is phyisical reason for 75%-90% wear engine occurs on cold start up? I can't find exact reason.. Is that beacuse ? 1) rich fuel mixture on choke, splash oil film from cylinder wall? 2)corrosive wear on cylinder and piston rings? 3)cold oil don't lubricated well?? (but oil when is cold...

Homework Statement [/B] Im trying to find the efficiency of a gasoline engine regarded as a control volume. Am I right to use the HV as total energy input into the system? Assuming the enthalpy of formation of the fuel can't be found. I am really wondering if enthalpy of formation equals the...

So I was browsing wikipedia when I encountered: What does this exactly mean? How does one calculate for this? << Adding link to the table >> https://en.wikipedia.org/wiki/Spacecraft_propulsion#Table_of_methods

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Why can't u make two way port opens when it sucks in air and fuel but closes when combustion happens eliminating 2 stroke and even 4 stroke design

Hello all, I have been tasked with writing a very short article regarding the use of computers and software in early jet engine design up to modern times. I've been having a relatively hard time finding reading material through Google. I understand that modern jet engine designers use CAD...

Are large two stroke engines with cross-head bearings reversible?

Hello. I wanted to see how much more efficient a car would be if hydrogen and oxygen (created through electrolysis of water) were injected into the engine alongside gasoline. I got lost when I found out that I would need 241.8 kJ/mol of water to electrolyze it...

Hi. I'm a student of electrical engineering, and I've always been interested in the idea of electrical cars, so I came up with a question: let's suppose we want to have a normal trip with car, and then we're not interested in going so fast with it. When we are driving in this condition, it isn't...

A possible ideal-gas cycle operates as follows: 1. From an initial state (##p_1##, ##V_1##) the gas is cooled at constant pressure to (##p_1##, ##V_2##); Let's call the start and end temperature ##T_1## and ##T_2## 2.The gas is heated at constant volume to (##p_2##, ##V_2##);Lets call the...

Homework Statement 2 bodies with contant heat capacity C and 2C, are initially at temp T and 2T. if a heat engine executing a reversible carnot cycle operates between the two bodies until their temperatures are equal, what is the final temp of the bodies and how much work is preformed by the...