# Questions tagged [turbomachinery]

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### How many turbos is too many? logistically and physically speaking

I want to build an engine simply to create as much horsepower as possible; Not necessarily to put into a car, just to have a fun project that is powerful. so of course I'm trying to max out all the ...
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### What is the theoretical Head of a centrifugal pump when an infinite number of vanes are asssumed?

I came across this question in my Fluid Machinery Course: A centrifugal pump of 1.25 m diameter is designed to pump 1.5 m3/s through 75 m height, whilst running at a speed of 600 rpm. At outlet the ...
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### Dual-independent turbo engine possibilities

My coach wants to mod his engine, so I was throwing around the idea of possible turbo setups. One that I started to like the idea of was the idea of two turbos, working independently. Is it possible ...
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### Is front shroud more thick than the lower shroud used in impellers ? Thickness of shrouds of shrouded impellers used in turbo pumps of rocket engines

This is an impeller used in turbopumps for increasing the pressure of propellants to drive the rocket engines. I wanted to ask all the engineers currently working in manufacturing of these impellers ...
43 views

### Dixon/Hall's "Fluid Mechanics and Thermodynamics of Turbomachinery" full of errors?

Note: This is no homework, but self-study. I have a thermodynamics and fluid mechanics background and am trying to work through this book in order to get better understanding of turbomachines (...
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### Centrifugal Compressor selection

I am currently trying to select a centrifugal compressor for a wind tunnel project. The requirement is that the flow velocity in the test section is Ma 0.1. The geometry of the wind tunnel has already ...
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### Aerodynamic design and characteristic of fan vs blower

I just learnt about the difference between a fan and a blower, namely the former providing high flow rate at very low outlet pressure (<1.1*inlet) and the latter providing a slightly increased ...
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### Kindly explain this graph which is related to internal combustion engines

Hello, I am not getting this graph which is related to the Internal Combustion Engine.
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### Why does flow capacity of axial turbine decreases with increasing RMP?

when studying the compressor map and the turbine map of a gas turbine, I noticed that the flow capacity of the compressor increases with speed increase (RPM) and the flow capacity of the turbine ...
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### Euler's turbine equation derivation

I'm trying to expand my theoretical knowledge on turbomachinery, but I cannot decipher the equation derivation steps in the book I'm using. I attached the derivation steps bellow as an image. I ...
17 views

### Compression phenomenon in Axial flow compressor

It is quite difficult for me to visualize how axial flow compressors work, as in, how air gets compressed by just flowing through a series of aero-foil shaped stator and rotor blades. How and where ...
2k views

### How to find work done by compressors

Which one is correct method to find work done by a isentropic compressor? Method-1: Compressor power = mCpdT Where m = mass flow rate Cp = specific heat at constant pressure dT = Temperature ...
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A twin jet Pelton wheel has a mean runner diameter of 1.68 m & runs at 500rpm, each jet is of dia. 152 mm. The net head is 510 m. Bucket turns the jet through 1650 & relative velocity is ...
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1 vote
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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 ...
1 vote
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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 ...
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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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### 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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### 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
90 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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### 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 ...
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### 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.
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### 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 ...
1 vote
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### 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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### 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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### 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
311 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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### 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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### 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 ...
688 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 ...
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### 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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### 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 ...
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1 vote
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### 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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### 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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### 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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