Questions tagged [turbomachinery]

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What is the meaning of different temperature limits printed on turbo charger's boiler plate?

On the boiler plate of a turbo charger (Type seems to be TPS57-F32, probably an ABB model, but manufacturer is not displayed) I found the following temperatures: $$ t_{M_{max}} = 650°C $$ $$ t_{B_{max}...
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What drives the mass flow rate in axial turbofan between the compressor and the turbine when compressor is fully choked?

I haven't found the answer in the forum or elsewhere, but maybe I have searched badly, in which case please forgive me in advance. For a steady nominal operation of a turbofan, I have heard that the ...
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Centrifugal pump head-flow prediction with CFD

Given a volute pump casing, the impeller, and RPM how would one obtain a simulated head-flow graph? As for what I have seen in research papers most methods already assume input flowrate / pressure and ...
1 vote
1 answer
60 views

Axial compressor: How does it work that the stator vanes diffuse the flow to build up pressure, but also the flow area reduces?

I'm reading about how the stator vanes are diffusors, which diffuse the air flow in a axial compressor to a larger flow area to build up pressure BUT at the same time the compressor shows its overall ...
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2 answers
153 views

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 ...
3 votes
2 answers
163 views

Why do EMD turbochargers have so many blades?

On most turbochargers that I've seen, the compressor wheels have 6 full-length blades and 6 splitter blades, 7+7, 8+8, or 9+9. Even on large marine engine turbochargers this generally holds, like the ...
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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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1 answer
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Does pressure in a centrifugal compressor increase along the path of the flow?

Euler turbomachinery equation doesn't include a term for changes in flow area. But, an centrifugal impeller (not the volute) has increasing flow area along the path of the flow. Is the pressure ...
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1 answer
48 views

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 answer
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Effect of flow through a static hydraulic pump on its RPM

What happens when fluid flows through a static hydraulic pump? Will there be a negative RPM to impede the flow? By static pump, I mean a pump with initial RPM = 0.0 and is not driven by external ...
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How is the ideal Euler line on a pump curve derived?

This website provides Euler’s equations for turbomachinery and solves a sample problem using velocity triangles. The problem prompt only provides the speed of the pump and the geometry of the pump and ...
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1 answer
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How to interpret the phase plot from an accelerometer on vibrating machinery

Attached is a plot of amplitude vs frequency and on the inset phase vs frequency. I have constructed this phase plot via $\arctan\left(\frac{Im}{Re}\right)$ How can I interpret the phase plot or ...
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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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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2 answers
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Advantages of hydrogen gas turbine over fuel cell

In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient ...
1 vote
1 answer
65 views

What is the diffusion process that takes place in a diffuser/stator?

I understand mass diffusion. But what is the meaning of 'diffusion' which converts the kinetic energy to rise in pressure in a stator/diffuser?
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1 answer
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Relation between Inlet and Outlet mass flow rate for a turbocharger?

For the compressor maps for automotive turbochargers, the Corrected mass flow rate (at inlet) is given as abscissa. However, I wish to know the mass flow rate at the outlet. What is the relation in ...
2 votes
1 answer
60 views

What gives gas turbine/turbojet engines such high energy density?

What is the cause of turbojets'/gas turbines' high power to weight ratio compared to piston engines? They certainly use a generally less efficient thermodynamic cycle.
1 vote
1 answer
158 views

Pressure recovery in turbomachinery

Diffusers in turbomachinery are used to transfer some of the kinetic energy of the fluid to pressure energy and to direct the fluid to the ducting/second stage/... I understand this and the mechanism ...
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0 answers
27 views

Turbocharger boost control using two valves with a vac and boost reference for wide boost control range

Can someone explain how the above boost control setup would work. The valve on the left uses a vac source applied to the top of the diaphram which would effectively help hold the spring closed at high ...
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1 answer
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Relationships among turbo jet rpm and compression ratio and thrust

A question about performance of a turbojet. Why are compression ratio and thrust are not in linear but increase exponentially with RPM?
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2 answers
381 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 ...
1 vote
1 answer
270 views

How do I calculate the force coming from the centrifugal compressor exhaust?

Let's say I have a centrifugal compressor as shown in the figure and I know the following parameters----1 Thrust Inlet and outlet pressure Power required to operate the compressor Inlet and outlet ...
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How is the number of blades on a centrifugal compressor determined?

If I know the tip and hub diameter of a centrifugal compressor ,the inlet velocity and outlet velocity, how do I determine the number of blades on a centrifugal compressor?
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2 answers
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Why doesn't axial turbomachinery blades block fluid from flowing?

I know this is a silly question, but shouldn't the high speed rotating blades (in case of an axial air compressor or an axial air fan for example) block the air from flowing? What makes air flow ...
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1 answer
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Working of a fan or propeller

I can roughly understand the working of an axial flow gas turbine i.e. the fluid moves over the blade and gets redirected, its whirl velocity component changes and the blade is pushed in the opposite ...
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8 votes
1 answer
681 views

What is the physical meaning of pulse rate and blood pressure, from a turbo machinery point of view?

Our hearts are peristaltic pumps, which has a periodic compression and expansion. The head developed can be taken as blood pressure. There are situation when the blood pressure is normal while the ...
1 vote
1 answer
356 views

Why regenerator "wheels" in a turbine engine?

Back in the early 60s, Chrysler built a turbine car powered by a turbine engine it had under development. An interesting feature of the engine was a regenerator system to recover heat from the gases ...
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1 answer
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What is the purpose of a vacuum cleaner's bypass valve?

I took apart a cheap domestic vacuum cleaner because I am making a small vacuum-forming system, and I only need the motor/fan assembly, so I repackaged it to save space. Inside the vacuum cleaner is ...
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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 ...
1 vote
1 answer
179 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 ...
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1 answer
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What is the difference between turbo wastegate and variable geometry turbo?

I don't see what the difference is between turbo wastegate and variable geometry turbo. Both seem to allow some of the gas flow, without turning the turbine, ie. bypassing the turbine, have I ...
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How do Cogs and belts work? / Cogs and belts in an ICAS exam

Does the left red wheel turn in the same direction as the leftmost orange wheel?If so P and S go up? If not, Q and S go up? My reasoning: If so Leftmost orange cc Left red cc (by assumption) ...
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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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1 vote
1 answer
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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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Power/Efficiency of expanding air-flow

Assuming, I've got a machine, that runs with pressurized air and provides the following measurements: $\dot m$ - mass-flow through the machine (same for input and output) $p_{1}$ - input pressure $...
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6 votes
3 answers
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Turbocompressor spool geometry

How come axial compressors always narrow and turbines always widen towards the rear? From what I know: The speed of sound of air increases with temperature, therefore increases (decreases) as it goes ...
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2 answers
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Mechanical Linkage Question - Velocity Diagram

Can someone confirm the velocity of B, given point C has velocity of 3 units/s down and point A has a velocity of 5 units/s upwards? My approach has been to resolve for the tangent velocity component ...
3 votes
2 answers
8k views

What's the difference between impeller and rotor in centrifugal pump?

The two terms seem interchangeable and I can't find a strict definition for both, so what's the difference between them if there is any?
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4 votes
3 answers
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How to increase the air flow rate through a dust-separating cyclone?

I'm making a dust extractor for a desktop CNC milling machine. My design process was very crude: I looked at some DIY dust-separating cyclones, and it seemed like they just work without any advanced ...
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6 answers
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What will happen if I run a submersible pump without water?

I have a submersible pump and it's clearly stated in the user manual that it should not be operated without water. But what will happen if it's not adhered to? The obvious answer is that it will ...