rul30
  • Member for 6 years, 9 months
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How an airfoil works
6 votes

It is true that the air on the "top" (suction side) is faster than on the "bottom" (pressure side). The interesting thing is that the air on the suction side is so fast, it overtakes the air on the ...

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efficiency and flow separation
6 votes

You are describing a very interesting engineering problem. The requirement of a turbine is to convert fluid-energy into mechanical energy over a range conditions. Since the flow around the airfoils ...

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Exploiting fluid dynamics for the optimal design for gas mixing in a furnace
5 votes

As far as I understand your question you are looking for a way to diffuse/mix two gases into each other. The process is very hard to simulate "correctly" because of the characteristics of the ...

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Converting air flow rate between kg/s and m^3/s
5 votes

HVAC-Systems usually give a Volume-Flow-Rate, hence $m^3/s$. If you need Mass-Flow-Rate ($kg/s$) you simply need to multiply with the density ($\rho$) of the fluid. The density can be calculated using ...

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Explanation of supersonic flow differences between a 2D wedge and a 3D cone
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5 votes

The answer to this question is complicated since the flow is fundamentally different. When supersonic flow hits a wedge it is abruptly turned by one oblique shock. After this all streamlines are ...

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Can redundancy be used instead of periodic calibration?
4 votes

The topic is – as easily seen from length and number of answers – not easy. This also means it does highly depend on every specific case to answer this topic. Part I: If we define that the process-...

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Increase static pressure
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4 votes

In order to get the air through the pipe, the pressure rise of the first fan has to be so high, that the pressure-loss within the tube is compensated. Since your first fan (F1) is not powerful enough ...

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Why do pumps really exists?
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4 votes

hm... I presume the term does not compress is what kicked of this question. Right? The task of a pump is to store energy in the fluid (potential energy in the form of pressure). This stored energy ...

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How to determine whether a particular velocity vector will result in a laminar flow?
4 votes

I am afraid the question you are asking might not even be a valid question. This is because of the correlation between the Reynolds-Number ($Re$) and the occurrence of turbulence. $Re$ is not a fluid ...

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What is the best method to generate heat from a compressed air canister?
3 votes

One possibility would be to use the air to drive a turbine (probably a radial turbine as they are used in turbochargers). The turbine could be connected to a generator and the generator to a resistor. ...

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How do I select an appropriate turbulence model?
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3 votes

Disclaimer: As you requested general guidelines here they are. After having a converged solution, you need to investigate it thoroughly and look for clues that the choice of the turbulence model ...

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What makes a flow periodic in Turbomachines?
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3 votes

The words unsteady and periodic have different meaning depending on the context they are used in. My answer is mainly with regards to axial or radial turbomachines. Lets say our machine is running at ...

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Why does blood pressure cuff size matter?
3 votes

I would guess that there is more than one reason to that (However, I am speculating, since I could not find any technical research on it). But in general the question is what effects can lead to a ...

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What is the physical interpretation of the second term in the viscous stress tensor in the Navier-Stokes equations?
3 votes

I agree with @sturgman one should not look at individual parts but try to understand it in ints context. Looking at the very basic version of the Navier-Stokes-Equation (using Einstein-Notation): $$\...

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How to know whether the flow is supersonic in a nozzle?
3 votes

That is a really nice thought experiment! In general I would argue that you only need to know: Total-Pressure ( $p_t$ of your supply) Static/Ambient Pressure ( $p_\infty$into which you are expanding) ...

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Would an object at the bottom of the sea still experience buoyancy?
2 votes

This question is a theoretical/academic edge-case. A body in the water will experience two forces: Pressure acting on all surfaces in contact with water Gravity acting on the mass of the body The ...

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validity of adiabatic equation
2 votes

An adiabatic and reversible process (i.e. isentropic) for ideal gases can be described as follows1: $p \cdot V^\gamma = \mathrm{const.}$ Here $\gamma$ is the heat capacity ratio. Other processes ...

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Is gravity included in "static pressure"?
2 votes

Without any further information on where you want to apply "Bernoulli" it is hard to answer the question. But in general the static pressure $p$ does not include $\rho g z$. Lets recall again ...

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Why does the standard $k-\epsilon$ model use zero equation models?
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2 votes

There are two ways of "wall treatment" both feature two layers but at different $y^+$. The general idea is that the velocity gradients in the boundary layer are so high that one would need a very high ...

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Understanding pressure drop and mass average values
2 votes

Averaging is a tricky business (see Cumsty 2006 for an introduction). Basically the problem is, that our thermodynamics usually talk about a pressure and a temperature etc. But in real life the ...

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How can flow in a centrifugal compressor at fixed conditions vary?
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2 votes

In general every compressor (axial and radial) will deliver a certain flow rate depending on the back-pressure down stream of the compressor. So by changing the pressure difference over the compressor:...

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What is the Boussinesq approach?
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2 votes

The basic assumption of the RANS approach (see the answer by @Algo) is that there is an overall steady solution to the problem. This overall steady solution features small scale oscillations around ...

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Thermal efficiency affected by hertz (Gas turbine)
1 votes

There are multiple effects how net-frequency impacts the GT-efficiency. But it also depends on the GT-architecture. The following effects also impact the efficiency even if the 50 and 60Hz version ...

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Using pressure drop to correlate mass flow
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1 votes

It is not entirely clear from the question, where the instrument readings take place. The following equations might need to be adapted in order to reflect the sensor positions. The basic equation for ...

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Incompressible flow field and Solenoidal flow field
1 votes

TD;DR: No Compressibility is a characteristic of the fluid (or maybe also the way you describe a problem). $\frac{\partial \rho}{\partial p} \neq 0 $ This means the a pressure variation will also ...

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Convection Heat Transfer
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1 votes

Assuming incompressibility you can work with volume-flow to calculate (a first guess) the velocity, $u$ with the following equations. Probably you have some volume or mass $\dot{m}$ flow entring at (...

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How do you calculate the Enthalpy of a geothermal resource?
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1 votes

Nitpicky Answer: you can't. More Detailed Answer: While enthalpy is commonly treated as an absolute quantity it is a thermodynamic potential. This is why textbooks might show the definition as \1\: $...

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Is there a generator that uses night and day this way?
1 votes

At the very basic level, this is how steam turbines or an organic rankin cycle in solar thermal power plants work. https://www.barber-nichols.com/sites/default/files/wysiwyg/images/...

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How to generate a NACA 6-Series Airfoil analytically?
1 votes

Sorry, I got this completely wrong! The equation is not the profile contour but the chamber-line. Since a symmetric airfoil does not produce any lift, this ($y_c$) should be a straight line (which is ...

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Aerodynamic Turbocharger Design
1 votes

Regarding point 1: To be honest I am not 100% sure. However, here are my thoughts: As with all profiles the turning of the flow is easier when it is accompanied with a pressure gradient (from high to ...

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