A CFD Study of the Ejector Pump Effect within Jet Engine Test Facilities
Collection editors:
ISJPPE
Title of conference publication:
ISJPPE 2012
Subtitle of conference publication:
proceedings of 4th International Symposium on Jet Propulsion and Power Engineering
Conference title:
International Symposium on Jet Propulsion and Power Engineering (4., 2012, Xi'an)
Venue:
Xi'an, China
Year of conference:
2012
Date of conference beginning:
10.09.2012
Date of conference ending:
12.09.2012
Year:
2012
Pages from - to:
10
Language:
Englisch
Abstract:
If a high momentum core mass flow is released into a
detuner, the developing shear layer between the core and its
surrounding is causing momentum and energy transfer leading
to entrainment of secondary air. This mechanism is called
ejector effect and is utilized in many applications. But also in
enclosed jet engine test facilities the hot and fast exhaust gas
causes entrainment of secondary air. This can lead to
substantial test cell depression which in turn can cause
enormous mechanical loads on the facility structure.
Particularly with regard to modern high-performance jet
engines a fundamental understanding of the ejector effect is
necessary to maintain safe testing and research operation.
Because of the fact that investigations on the ejector effect with
real jet engines are very extensive in costs and time, thus the
Institute of Jet Propulsion of the University of the German
Federal Armed Forces Munich has built a scaled model of the
institute’s sea-level engine test bed to get further insight into
the physics of the ejector effect. Subject of the presented paper
is the numerical simulation of the flow through this simplified
low-cost test-bed with special attention to the interaction of the
primary and the secondary mass flow. Parallel conducted
experimental investigations are published by Bindl et al. [1] in
the accompanying paper.
The numerical simulation includes intensive sensitivity
analyses on input data required at boundary conditions which
were not determined experimentally. Also simulations of
different engine power settings ranging from idle to maximum
power with three different detuner to nozzle area ratios
(DNAR) have been conducted. This was made to investigate
the influence of the geometrical configuration on the macro test
cell aerodynamics as well as on the ejector effect quantification
parameters like the entrainment ratio and the test cell
depression (TCD).
Since the corresponding setups have also been
experimentally investigated a comprehensive validation of the capability of the numerical simulation in calculating the ejector
effect in terms of qualitative and quantitative compliance is
enabled. «
If a high momentum core mass flow is released into a
detuner, the developing shear layer between the core and its
surrounding is causing momentum and energy transfer leading
to entrainment of secondary air. This mechanism is called
ejector effect and is utilized in many applications. But also in
enclosed jet engine test facilities the hot and fast exhaust gas
causes entrainment of secondary air. This can lead to
substantial test cell depression which in turn can cause
enormous me... »