Hi.
Does anyone have any references to how a diffusor should be designed, i.e. angles vs. velocity.
My "diffusor problem" has air as fluid and an inlet/outlet velocity approx. 20m/s - 5m/s. I would like to avoid any detachment.
And, does anyone know if a diffusor flow is inherently unsteady...
Hi.
I want to make an analysis of a device to find its eigenfrequency. But I am not sure how to do it.
I seem to remember something about an FFT analysis of the frequency recorded, but that’s it. If anyone could help me with direct informations, I would be most grateful. Links are also...
When making a frequency measurement, one has to make sure that the Nyquist criterion is obeyed. But what if I have no frequency filtered data. Is it correct to make a FFT transformation and just look at the first half of the transformation? Is that the same as a low pass filtering?
Hi.
I have a duct with a 90° bend. After the bend I want to have a symmetric velocity profile.
But if I do nothing to the flow, the velocity distribution will be skew.
What can one do to even out the distribution?
And how far from the bend will the skewness remain?
Flow details: u=10m/s...
Hi.
I want to build a wind tunnel for calibration of hotwire, pitot tubes etc.
I have made the following considerations:
A large plenum where the velocity will be nearly zero (to measure the static pressure as upstream condition for outlet velocity calculation).
A baffle plate at the plenum...
Hi.
I want to build a wind tunnel for calibration of hotwire, pitot tubes etc.
I have made the following considerations:
A large plenum where the velocity will be nearly zero.
A baffle plate at the plenum inlet.
A honeycomb, screen or a similar device inserted for to ensure a flat velocity...
Hi all.
How can I determine the maximum velocity (the fluctuating turbulent part) in a flow that I estimate to have a turbulence intensity of 50% ?
I cannot see by looking at the definition of the intensity how I with the intensity and a mean velocity can calculate the fluctuating...
Hi
Can anyone help me with references to standards regarding pitot measurements and design ?
I know of two ISO standards (3966 and 7194) but they may be too old and there may be others. I have tried a search on ISO´s and EU´s standard homepages, but found no useful information.
Hi.
What is the best way to measure velocity approx 5m/s +- 0.1m/s in air approx 50C ?
A pitot tube would have to measure a difference of 0.005Pa to detect a 0.1 m/s change, and that is properbly impossible.
I think that a hotwire tool is the best solution, but I am not sure.
Any comments on...
When is there a 1. order relationship between velocity and drag, and when is it 2. order? And why is there a difference, and why 1. and 2. order and not 3. or 4. ?
I know that when the velocity is low the relationship is 1. order and when the velocity is high it becomes 2. order. But I don’t...
When calculating the pressure drop of a manifold using standard minor loss coefficients found in an everyday fluid mechanics book, it goes without saying that the calculated pressure drop will be an estimate only (due to the inconsistencies between the actual design and the “standard” loss...
How do I measure the velocity after a nozzle? The flow is not stationary.
I was hoping to use some variation of a optical measurement like LDA, but as I recall LDA is using tracer particles (right ?), and that is not an option because I can not be sure that the feed particles is uniformly...
Hi.
I need some guidance.
In an air duct with airflow of say 20°C, 1bara and u=20m/s I want to
calculate the effect of a short air pulse of say dp=1000mmWG, dt=1sek
in the opposite direction of the airflow.
How to calculate the travelled distance of the effect and the
magnitude. Where do I...
Hi.
When measuring rapid oscillating pressure, a pitot is a poor choice because of the dampening by the air in the tube and the fluid in the u-tube.
I would like to make an estimate of this dampening. How do I calculate the dampening?
Cheers Christian
