Questions tagged [turbines]

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Is there a type of rotary positive displacement pump that can pump hot exhaust gases?

Is there a type of rotary positive displacement pump that can pump hot exhaust gases (~900°C), that is, not requiring lubrication that would otherwise be burnt off?
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2 votes
1 answer
53 views

Fluid dynamics - Velocity required to turn wheel

I want to calculate the velocity of a fluid required to turn a water wheel at a specific angular velocity. The fluid enters the housing of the water wheel through a inlet channel. It turns the wheel ...
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3 votes
3 answers
117 views

Why not build a wind turbine like a vertical Kaplan turbine?

Vertical Kaplan turbines are often used for hydropower plants. They can have an efficiency of more than 90%. Why don't we see similar designs for wind power? I mean one could imagine to redirect wind ...
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Expected power increase when replacing old (>20 years) wind turbines [closed]

Plenty of onshore windfarms around the world are reaching the 20-25 year old mark and thus may be on the process of repowering. Let's say an old wind farm has 10 rotors of 0.5 MW each (total power <...
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Doubt on a shaft-turbine-generator system

Consider a shaft which connects a turbine to a generator. Initially, none of the parts are moving. Now the turbine starts to rotate and the torques act on the shaft from both the turbine and generator ...
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3 answers
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Confused about how combustor pressure is lower than compressor exit pressure in turbomachinery?

I understand the compressor exit pressure is the highest pressure in all of the turbomachinery, and the combustor is a constant pressure process, and since the combustor P is lower than compressor ...
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Theoretical calculation of blade pitch angle

I would like to start by apologizing for my ignorance, I am sure I am missing something very obvious here. I am using data for the NREL 5MW reference turbine, and specifically power curve and power ...
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-1 votes
2 answers
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Could the St. Louis Gateway Arch be used as a support structure for a giant vertical axis wind turbine?

I am curious to know if the St. Louis Gateway Arch would be strong enough to act as a support structure for a giant vertical axis wind turbine. I way I am envisioning this being constructed is that a ...
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Is transmitting windmills' mechanical power to ground level that complex?

Thinking about the complications of building and maintaining turbine rooms installed at high altitudes in horizontal axis wind turbines (plus the difficulties related to it when, for example, a fire ...
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1 vote
1 answer
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Angular Velocity And Flow Rate Relationship Of Turbine

I was designing a turbine to be utilized in order to measure the flow rate of a river system. I can measure the angular velocity of the shaft by utilizing a magnet and hall sensor, however, in order ...
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1 answer
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I want to determine the flow rate and required turbine size for an offshore hydroelectric scheme and need help

I'm creating a report on the possible implementation of a sub hydro system and need some help. I've attached the image of what I'm proposing, where I've essentially created a head via a riser B with a ...
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1 vote
1 answer
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Weibull distribution Units - ENGIEQSOL

I am using Engineering Equation Solver, and it has been telling me the units of my distribution are inconsistent. According to a the book I am reading, I think it should be unitless (as it is a ...
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What does the author mean? Turbomachinery - Reaction

I am reading a book of Fundamental Energy Systems. The author describes the rate of change in head for a turbomachine as: $$ \frac{1}{2}[(V_1^2-V_2^2)+(U_1^2-U_2^2)+(V_{R2}^2-V_{R1}^2)] = H =U_1V_{u1} ...
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-1 votes
2 answers
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Correct wind Weibull distribution for wind+solar system

I'm trying to forecast the peak power output for a wind + solar system. The solar output as a function of time of day and month can be forecasted easily. I also have the historical wind speed for a ...
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1 vote
2 answers
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Hydraulic energy recovery for high-pressure, low flow (non-steady state) conditions

What would be the best way to implement hydraulic energy recovery while de-pressurizing a pressurized volume of silicone oil initially at 1500 bar. Can a piston pump be concievably repurposed as a ...
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1 answer
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How to do Blade Element Momentum Theory Analysis for NACA airfoils?

I wanna perform BEMT analysis on blades of different geometry and not just symmetric thin airfoil. How to do this?
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Blade efficiency of a franscis turbine

The blade efficiency of a turbine is defined as the ratio of the power extracted from the fluid by the rotor to the power available at the inlet of the rotor. The power available at the inlet of the ...
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1 vote
3 answers
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Practicality of energy recovery from HVAC systems?

I've been thinking about ways to maximize efficiency in large buildings, and one thing I thought of was to place some sort of turbine in the exhuast vents or smokestacks of factories, power plants, ...
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Can a steam turbine can be used with compressed air?

Suppose that a generator is connected to the turbine. I have a large amount of compressed air which will be acting as the driving force for the turbine. For the above case will I be only left with the ...
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3 votes
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Why funnelling air in order to increase the velocity is a bad idea when generating power

Disclaimer: I’m not trying to violate the conservation of energy here; I know that’s impossible for us mortals. I think I’m either wrong or not considering something, I just want someone to point it ...
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2 votes
1 answer
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How should one clean the blades of a turbomolecular pump

I have a turbomolecular pump from Osaka vacuum that is quite dirty, and I'd like to clean the blades off to improve balance. I'm not quite sure how to approach this, I've tried carbon cleaner for ...
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what is the difference between jblade, qblade, and xflr5 softwares?

I am working on a propeller design, and I've came through Jblade which helped me in the airfoil design, yet as I can remember, xflr5 can also do this... doing some internet search, i found that Jblade ...
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-1 votes
1 answer
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Accounting for pressure energy in Euler turbine/pump equation

For all the analysis to find work done by a compressor or work done on a turbine, the book I'm reading (Fundamentals of Turbomachinery by Venkanna B.K) uses the Euler turbine and pump equation, $$W=\...
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1 vote
2 answers
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What is the purpose of combustor in a gas turbine

I have read online that a gas turbine converts the chemical energy in the fuel gas to mechanical energy of the turbine blades. The way I see it, because of this hot air one would have to go for heat ...
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1 vote
0 answers
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How many kWh this turbine would generate?

My grandfather and I are running some experiments down the river, however we don't have expertise in engineering so I bring up this question to the community and hope someone could help. How many kWh ...
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3 answers
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Some questions about the specific speed (Ns) of hydro turbines

So we all know the basics behind specific speed Ns of hydro-turbines. $$N_s = RPM \cdot \frac{ \sqrt{(P)} }{ H^{1.25}}$$ where P is the power output and H is the head. The theory is that once you ...
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-1 votes
2 answers
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What is and how do you calculate the wind velocity design for wind turbines?

I am finding it difficult to get consensus on the definition of design wind speed for aeolic turbines. I thought it was the velocity that corresponds to the maximum power output, but I have already ...
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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 ...
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2 votes
2 answers
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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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0 votes
1 answer
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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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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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0 answers
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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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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=...
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4 votes
2 answers
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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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2 votes
1 answer
124 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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0 votes
1 answer
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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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0 votes
2 answers
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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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2 votes
2 answers
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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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2 votes
3 answers
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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....
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4 votes
2 answers
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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 ...
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3 votes
1 answer
136 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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0 votes
2 answers
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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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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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1 vote
0 answers
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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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1 vote
2 answers
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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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2 votes
2 answers
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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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3 answers
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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 ...
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1 vote
1 answer
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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 ...
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2 votes
1 answer
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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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2 answers
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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?
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