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Jeg ved at der sidder en maskinmester eller to derude og derfor skriver jeg her. Jeg er igang med at afslutte mit bachelorprojekt som maskinmester og vil derfor gerne have jeres mening med på falderebet.

Turbo stall. Hvad er jeres erfaringer og hvordan har i oplevet det ? Hvad var årsagen og hvad er "jeres teori/holdning" ?

Jeg har været ude og sejle og derfor fisker jeg specielt efter folks erfaringer og holdninger i forhold til 2-takts hovedmaskiner.

Venlig hilsen
Jesper.

Jeg ville evt. prøve at fange Morten "And" på http://hi-speed.dk - han er lidt af en dieselmaskine-nørd.

_________________
Mvh.
Brian Klausen


Golf GTi 16V til rally

Er du ud efter et svar på hvorfor det sker? Når du skriver stall mener du surge?

Her lidt om emnet:

There are two severities of compressor stall.

"Rotational stall" is a local disruption of airflow within the compressor which continues to provide compressed air but with reduced effectiveness. "Rotational stall" arises when a small proportion of aerofoils experience aerofoil stall disrupting the local airflow without destabilising the compressor. The stalled aerofoils create pockets of stagnant air (referred to as "stall cells") which, rather than moving in the flow direction, rotate around the circumference of the compressor. The stall cells rotate with the rotor blades but at 50%-70% of the speed, passing to the next aerofoils around the rotor. Stable local stall can also occur which cover the complete circumference (axisymmetric) but only a portion of the radius of the compressor with the remainder of the passage continuing to pass normal flow.

A rotational stall may be momentary, resulting from an external effects, or may be steady as the compressor finds a working equilibrium. Local stalls substantially reduce the efficiency of the compressor and increase the structural loads on the aerofoils in the region affected. In many cases however, the compressor aerofoils are critically loaded such that the original stall cells affect neighbouring regions and rapidly grow to a complete compressor stall.

"Axisymmetric stall" more commonly known as "Compressor Surge" is a complete breakdown in compression resulting in a reversal of flow and a violent expulsion of the previously compressed air out the intake, due to the compressor's inability to maintain pressure. An axis-symmetric stall will occur when a compressor either experiences conditions which exceed the limit of its pressure rise capabilities: or is highly loaded such that it does not have the capacity to absorb a momentary disturbance. In this case, a rotational stall will quickly propagate to include the entire compressor. The compressor will recover to normal flow once the pressure ratio reduces to one that the compressor is capable of sustaining stable airflow. If, however, the off-design conditions that induced the stall remain, the return of stable airflow will quickly reproduce the other conditions at the time of surge, and the process will repeat.[1] Such "Locked-in" stall is particularly dangerous, with very high levels of vibration causing accelerated engine wear and possible damage.

personligt vil jeg betvivle, at det overhovedet forekommer på 2takts hovedmotorer, af en vis (stor) størrelse.
MVH søren

Tak for de gode svar

Jeg fangede det på video hvis det skulle have interesse
http://www.youtube.com/watch?v=S3pHfl_Q ... e=g-crec-u[/url]

Den video siger mig ikke så meget uden lidt forklaring???

Der er ingen tvivl om at det er skadeligt for turboladeren.

Trykstød over +/- 1bar 20-30x i sekundet kan ses på bilmotorer med compressor stall.
Compressoren flower mere end motoren bruger, og arbejdspunktet bevæger sig bagud i compressormappet og ud over surge linien, herefter staller den.

På store motorer vil jeg gerne tro at compressorstall bliver en halv-voldsom begivenhed, men jeg har aldrigt set det i praksis.

_________________
Henrik
http://boost-it.dk
Citat:My experience tells me that once the cam with the lumpy idle is selected, the thinking mostly stops. Decisions then are based on lowest price, looks, ease of installation, coolness factor, the 'latest thing' syndrome, peer pressure, old wives tales, and bad advice.
Citat slut.
Hold kæft hvor er det sandt!