Questions tagged [turbines]
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72
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Force exerted by a jet of water on a series of Radial Curved Vanes
Normally, when we calculate the force exerted by jet on vanes, we usually calculate the rate of change of momentum.
The momentum change is calculated using the relative velocity of jet with respect to ...
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35 views
Most efficient turbine for harnessing energy from bidirectional air flow?
I am currently working on designing an oscillating water column as part of a project. In summary:
OWC are devices with a semi-submerged chamber or hollow open to the
sea below, keeping a trapped ...
2
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2answers
59 views
Why don't we use hot water instead of steam to drive the turbines?
I guess if we do this then, the size of the turbines could become smaller.
The condensor's size also might be reduced.
But the catch over here is the energy density of hot water is less then that of ...
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1answer
32 views
How to calculate airflow in m3/min on a gas turbine outlet?
I'm currently trying to figure out the airflow of a gas turbine in m3/min.
I thought that i would be able to measure the windspeed over a known cross section on the intakte of the turbine and then ...
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17 views
Are there impulse turbines operating on hot exhaust gas?
Are there impulse turbines that operate efficiently on hot exhaust gases rather than water as the working fluid?
Im thinking about something analogous to a water wheel, since it seems that bucket/...
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20 views
What exactly makes reaction turbines work?
I was reading about reaction turbines on Wikipedia, it says: "Reaction turbines develop torque by reacting to the gas or fluid's pressure or mass. The pressure of the gas or fluid changes as it passes ...
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39 views
Can someone please give me a hint on how to draw velocity triangles for this specific inward flow reaction turbine problem?
I'm trying to calculate the hydraulic efficiency for this turbine by using the formula:
E(hyd) = (VwU)/gH
where Vw= Velocity of whirl at inlet, U=velocity of runner at inlet, H=Given Head, and g=...
4
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2answers
106 views
Do 3 blade wind turbines generate more power than a 9 blade, all else being equal?
After doing some research, I have come to the realization that 3 blade design horizontal turbines have the greatest maximum coefficient of performance. Most sources seem to agree a Cp of ~0.45 at TSR=...
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1answer
45 views
In horizontal axis wind turbines, why does axial component of absolute velocity stay constant (wake rotation theory)
I am having hard time understanding how does the axial component stay constant through the rotor. Every resource i look just says it is due to mass conservation but never gives the actual conservation ...
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1answer
44 views
Can turbine engines really run on “just about anything”?
I often read that turbine engines can run on almost any fuel source. I understand that turbine engines are less "picky" in terms of the fuel source that they can use, but surely there would still be ...
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2answers
39 views
How do turboshaft engines maintain a constant rpm regardless of load?
I understand that most turboshaft engines tend to run at (or close to) their most efficient rpm all of the time, and it is the load that is changed e.g. the pitch of the blade pitch on helicopters.
...
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42 views
How much power could a turbocharger generate?
I can find many figures online for the extra power generated when a turbo is fitted to an engine. However, I can't find any figures on how much energy the turbocharger turbine actually takes out of ...
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2answers
23 views
Gasturbine energy balance
I have a question regarding gasturbine energy balance,
the total energy that flows into the gasturbine is given 12 MW and the power needed for the compressor is 4.4 MW and the turbine power is 9.3 MW....
1
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1answer
69 views
Tesla's Turbine in Real Life
Internet search results don't give much results of real life examples of bladeless turbine. Has anyone ever seen a working real example of Tesla's bladeless turbine, in some industrial or other ...
3
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1answer
50 views
What is the difference between a diffuser and a duct in turbines?
I have been reading this paper, which addresses the advantages of diffusers in cross flow turbines.
The abstract says (emphasis is mine):
A CP’s extraordinary improving resulted when yaw increased ...
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2answers
66 views
If the turbine drives the compressor, then what limits the engine speed?
My understanding of a typical jet engine is that when running, the turbine extracts energy from the hot exhaust gases. This drives the turbine, which is coupled to the compressor at the front of the ...
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0answers
38 views
Would an afterburner on a turbine drastically improve acceleration lag?
A little bit of context. My friends and I were watching the "Dark Knight Rises" and a discussion about the Batmobiles ensued. I, being a former ME student, said it was stupid that batman has a turbine ...
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45 views
How is a Steam Power Plant designed?
I asked this question at physics but i think this suits it more. I'd like to know few things about how does one design a Thermal Power Plant? There is something fundamentally lacking in my knowledge ...
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2answers
64 views
Why aren't turbos/turbines controllable pitch?
I am wondering why turbines are not implemented with controllable pitch blades (on the rotor system)? I assume the reason is that the coupling between the stator and rotor systems posed by typical ...
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2answers
83 views
Is it possible to extract mechanical energy using Turbines behind PulseJet engine?
Pulsejet expels pulse of hot gas (unlike turbojet engine) which create some thrust(Not good enough for ). These gases are hot, fast and pulsed. Is it possible to convert kinetic energy of these gases ...
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3answers
52 views
What determines the cost of the wind turbines?
If there is an 11kW wind turbine, and a 15kW wind turbine. Why is the 15 kw wind turbine more expensive?
I know it seems like a basic question, but what exactly makes it more expensive? Is it only ...
1
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1answer
43 views
Is it possible to determine tip-speed ratio from rotor geometry?
Let's say I have the geometry of the rotor: the number of blades, the airfoils that make up each blade, their position, chord length and their twist angle. Would it be possible to use this information ...
2
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1answer
50 views
Generating practical power without an iron core, but with high RPM
Here's what I'm proposing - a small turbine directly coupled to a permanent magnet that's spinning at, say, 150k RPM. The magnet is enclosed one or several wire loops parallel to the axis of rotation.
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47 views
Thermal efficiency affected by hertz (Gas turbine)
Take the LMS100 gas turbine for example. Why does the efficiency change when generating power in 50 or 60hz waveform?
3
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2answers
80 views
Compressed air energy storage?
I'm wondering, if you put an air compressor pipe into a micro turbine, lets say something like that attached to a motor, does air that get out of the turbine have the same energy as when it gets in ?
...
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70 views
What is the exact meaning of “static and dynamic torque”?
I have the following parameters in my project.
enter link description here
I submitted a paper. Now, one of the Reviewer's comments is as follows:
Validation is not enough and convincing. The CFD ...
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1answer
24 views
When were airfoil cross-sections first used in turbine blades?
When were airfoil cross-sections first used in turbine blades? When did this become standard practice? Did people understand the connection to aircraft, or did heavier-than-air aircraft exist at all ...
2
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1answer
56 views
Estimating wind velocity behind a wind turbine
According to the Wikipedia page on the Betz Limit, the outgoing wind velocity behind a wind turbine can be as low as 33% of the incoming wind velocity. However, this figure assumes that the turbine is ...
3
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3answers
320 views
Why not design a Wind Turbine like an Anemometer?
Anemometer measures wind speed. It's shaped with little cups---hollow half-spheres. That looks very logical as the cups grab the wind and the other side is rather streamligned to cut through the air ...
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1answer
65 views
Does the turbine outlet affect the power generated by the turbine ?
In my text book , it is written
"Power generated by the turbine can be increased by using a gradual expansion at the turbine outlet"
The picture below explains the meaning of gradual expansion at ...
3
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1answer
147 views
Can combined cycle turbines be small enough for trains?
Combined Cycle Turbines are a gas turbine whose exhaust heat powers a second turbine running on steam. These can get thermal efficiencies greater than 50%, whereas a plain turbine would get 30 to 35%. ...
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1answer
67 views
turbojet axial compressor: blades of HP compressor
I noticed that blades of HP compressor are shorter in axial dimension next to its LP counterpart.
Why?
I understand why it is smaller in radial dimension (this is because compressed air has smaller ...
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1answer
119 views
In what order turbojet engine parameters are calculated?
As I see it, if you're going to calculate a twin-spool turbojet engine, you
Determine expected max aircraft speed, and engine thrust at that speed and when stationary.
Calculate peak mass of air flow
...
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4answers
903 views
Is it possible to use Ammonia vapor in steam turbine
I am currently designing a prototype. I have asked to use low boiling point liquid to run a steam turbine. So i am thinking of using liquid ammonia.
What are the complications involved when using ...
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329 views
Why is there negative static pressure in contour?
I studied a paper about turbine and i seen that there is negative static pressure in contour. Why does this happen?
Wave Energy Harvesting Turbine: Performance Enhancement
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2answers
287 views
What is reason of low axial velocity at tip and hub of an axial turbine?
I am analyzing results of my turbine simulation. I have created one line from hub to casing at downstream of the flow...please see the following figures. I want to investigate along this line how the ...
2
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1answer
134 views
Does this exist - Water flow control with energy recovery
Classically, if you have free flow (high level to low, no pump) between two vessels you want to control you use some restricting orifice, or flow over a variable height weir. Both dissipate energy.
...
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121 views
Why is more steam required to turn a steam turbine when electric power consumption is higher
I'm recently under industrial training at a plywood mill. My supervisor is from foreign country so there are some difficulties for me to understand what he is trying to say.
In the power plant, the ...
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4answers
1k views
What is the theoretical maximum energy efficiency of hydro turbines?
From what I've read it seems that hydro turbines can theoretically achieve 100% energy conversion from kinetic to electrical energy. However, I just wanted to double check if this was true.
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1answer
273 views
What prevents the use of electric engines to assist with spacecraft launches? (Space Shuttle Booster Supplement)
Much power is used to get rocket off the platform on the initial launch? Could electric engines used like booster rockets work similar in the way they launch planes of an aircraft carrier? The ...
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0answers
55 views
Is it possible that entropy generation decreases with decreasing turbine efficiency(First Low efficiency )?
I simulated an axial turbine(Wells turbine). Now I have faced with strange problem.
Performance of any turbine can be improved if the losses are identified and minimized. Several losses can be ...
3
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2answers
91 views
Question about bounday layer thickness?
According to the following figure, boundary layer becomes progressively thicker with downstream distance x . Why?
I have an other question as follows:
When turbine blade thickness increases, what ...
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1answer
153 views
Why do thicker turbine blades delay flow separation? [closed]
I studied about the effect of turbine blade thickness on flow separation in following. The blade section is Naca 00 XX in this turbine.
The paper states that if blade thickness increases, separation ...
4
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1answer
231 views
Why does my model of a wind turbine show high RPM with low power output?
I am designing a wind turbine to generate 1300 W.
I modeled the output voltage of an AC generator using the following specifics:
Number coil turns = 300.
Copper wire gauge = 1.02 mm.
Knowing the ...
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0answers
52 views
How to design a fan that can be used to convert concentrated air to power [closed]
I am trying to design mechanism that is sort of like a wind turbine (uses wind as "fuel") but has a fan size that is in a pelton turbine. I was wondering if there is any math/equation that I can use ...
6
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1answer
134 views
Streamlines at the boundary of rotating and stationary domains are malformed
I am simulating a turbine and have divided the mesh into domains: the piping before and after the blade and the turbine blades. The domain containing the blades rotates at 2000 rpm while the other ...
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0answers
35 views
How to set up the boundary between volumes in a simulated turbine
I am simulating a turbine and I have some doubts about the correctness of my approach.
In this turbine, there are three volumes:
The two volumes are the piping before and after the blade and the ...
2
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0answers
64 views
problem in the calculation of pressure drop for an axial turbine
I am simulating an axial turbine. In this turbine, there are two domains.
The first domain is the piping before and after the blade and the second domain contains the turbine blades. The domain ...
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2answers
559 views
Calculating water turbine mass based on head and flow [closed]
Is there a formula, which would allow to estimate water turbine rotor mass based on head and water flow, or based on the final energy output provided by the turbine? I am interested in rough estimate, ...
4
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1answer
632 views
How many blades for a steam turbine?
I am building a very simple turbine that runs on steam. I want to make it as simple as possible, thus avoiding impulse and reaction turbines.
I want to design the turbine to fit in an exhaust pipe (...
