Untersuchungen zur Entstehung und Stärke von Triebwerkseinlaufwirbeln

A vortex system can occur in an inlet of a jet engine operated near the ground. These vortices reach into the inlet and can show significantly different strength and shape dependent on several geometrical and flow parameters. The inlet-vortices often form especially with a foot on the ground when the inlet is close to the ground, the suction speed is high and the wind speed is slow. This situation is found on every take off and stationary engine test. The inlet-vortices can endanger the jet engine. They are able to lift particles from the ground, which can damage the engine. They can also cause compressor surge and a strong disturbance of the the inlet flow, resulting in additional noise, vibrations and dynamic loads. The study at hand combined three methods of experimental investigations in order to develop a full picture of the system of inlet-vortices and deepen the knowledge of the mechanisms of inlet-vortex formation. 1) Two split-fiber probes were rotating very rapidly inside the inlet of a model engine measuring the velocity distribution of the inlet-vortex quantitatively and without averaging. For the first time, these data sets showed the inlet-vortex structure, position and strength as a function of the flow parameters and the geometric arrangement. 2) Additional data sets came from flow measurements outside the inlet. The especially developed measurement technique allowed the coverage of a large area in a short time by gathering data with moving probes. 3) Flow visualization studies completed the results and gave additional information about the formation, stability and strength of the inlet-vortices. These findings lead to the conclusion that the system of inlet-vortices is more complex than previously thought. The inlet-vortex system always consists of two counter rotating vortices. Often two pairs occur. The configuration of the system changes with variation of the parameters especially the inlet velocity and the wind speed. It is shown that there are five different vortex pairs which have their own formation mechanism and source of rotation. Finally, the effectiveness of devices in suppressing the vortex formation or reducing the vortex strength was investigated. For this purpose, a shield was constructed reaching from the ground to the lower lip of the inlet. This shield separates the flow in front of the inlet from the flow underneath it and successfully prevents the inlet vortex formation.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2004

Author dc:creator

• Brix, Stefan Christoph Markus

Contributors dc:contributor

• Jacob, Dieter

• info:eu-repo/classification/ddc/620
• Luftstrahltriebwerk
• Einlaufströmung
• Wirbelströmung
• Messung
• Strömungssonde
• Strömungsfeld
• Visualisierung
• Ingenieurwissenschaften
• Einlaufwirbel
• Triebwerkseinlauf
• Bodenwirbel
• Wirbelsystem
• Wirbelmodell
• Splitfilmsonde
• rotierende Sonde
• Sichtbarmachung
• inlet-vortex
• jet engine intake
• ground vortex
• vortex system
• vortex model
• split-fibre probe
• rotating probe
• flow visualization

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-121676%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:59936