Pulsed jet heat transfer enhancement.

[redhead78]

I'm starting to investigate the properties of a rectangular pulsed air jet impinging on an heated cylinder.
Current bibliography lacks of articles about it: If you have any document about it, please let me know.
The goal of the research should be the demonstration that pulsation enhances convection heat transfer in some range of Reynold's number (to be found).
If somebody else ever investigated the same problem, please let me know how you realized the pulsation (motor driven ball valve, three ways solenoid valve, etc.).
Moreover I wish to know the most widely used averaging techniques for the comparison of data of the pulsed jet with the data of the heat transfer with continuous jet.
A colleague of mine found here very important tips for his work, so I hope it would be the same for me! Thank you.

 

[poetix99]

Pulsed combustion for enhanced heat transfer and/or fuel efficiency has been researched for various applications, including residential/commercial water heaters and commercial appliances such as cookers, dryers, etc.

I am sure that some of the work is proprietary, but also expect that some things have been published. I know that the Gas Research Institute (GRI) had funded some work of this sort in the 1980s.

I do not have any references for you, but I am surprised that you are unable to find some citations. If you find nothing on the web, try some technical journals or a search service like NERAC.

 

[redhead78]

Sorry poetix99, maybe I didn't explain my problem so well as I should do.
My experimental apparatus doesn't deal with combustion, but it is a cooling assembly: it is composed by a small wind gallery supplied by a centrifugal compressor. The air passes through a rectangular duct and impinges on a cylinder heated with electrical current.
I want to investigate if there are enhancements in heat trasfer when the air supply pulses, by comparing it with the heat transfer (Nusselt number) in the case of continuous air flux.
If you have any information about such an experience, please let me know.

 

[poetix99]

The "sorry" is mine; you did say "air jet", not flame or combustion gases.

Sorry, no leads, but I share your apparent suspicion that pulsing should enhance h.t. for some range of flow parameters (Re, Pr, ...). Pulsing should keep the shear layer thinner and/or increase bulk mixing.

Good luck.

 

[radomir]

Interestingly enough I had the same understanding of your query at the first glance as Sir Poetix. Seeing that "pulse jet" I immediately had V1 in mind (German WW II projectil with a pulse jet engine). Therefore I strongly suggest to re-post the question with more accurately descripting title (if you want more helpful answers).

Regarding your question I am not of any help. The only thing I know is that impingement cooling is the best, the highest convection coeficient (gas turbine blade leading edges are inpingmently cooled from inside - holow blades). But in such case it is a continuous compressed air flow from a gas turbine compressor.

Do change the title or you are doomed to get useless answers like mine