Ejector tip injection system for active aerodynamic compressor stabilization part I: design and experiment

Abstract

The subject of compressor tip air injection in full jet engine test setups has been under investigation at the Institute of Jet Propulsion for many years. Latest experiments revealed that the utilization of the ejector effect can help to raise both effectiveness and efficiency of air injection systems. Based on the gathered experiences, an advanced Ejector Injection System (EIS) was designed from scratch and built most recently. The presented design process is focused especially on the optimal application of the ejector effect in order to achieve maximum performance. As the EIS features complicated 3D flow paths and utilizes not only the ejector but also the Coanda effect, its internal aerodynamics include complex interactions of multiple phenomena. Therefore, extensive stand-alone tests are performed before the ejector injection system is attached to the jet engine. The described test setup features high precision mass flow measurement devices and has created valuable results for a more detailed understanding of the ejector effect and the flow inside the EIS. The experimental work is accompanied by extensive CFD simulations with detailed focus on the internal flow phenomena in the second part of the paper.

Ejector tip injection system for active aerodynamic compressor stabilization part II: CFD investigations

“…This chapter comprises only a brief overview of certain EIS features which are important for the CFD simulations of the inner aerodynamics. More details about concept, design, mechanics, and manufacturing can be found in the accompanying first part of the paper by Kern et al (2017). Figure 2 depicts a cut through the EIS attached to the Larzac 04 jet engine with the main components outlined.…”

“…First, several sensitivity studies concerning the mesh resolution respectively the boundary layer treatment and the necessity to apply a transition model are conducted. The CFD predictions of the final setup are validated utilizing experimental measurements of static wall pressure distributions and the air mass flow rates involved as outlined in the first part of this paper by Kern et al (2017). This data is also used for detailed analyses of the flow conditions within the main aerodynamic components of the EIS.…”

“…Stößel et al (2014) have proven experimentally that deploying the ejector effect in the previously described manner can significantly improve impact and efficiency of the entire air injection concept. Based on these findings, a further advanced Ejector Injection System (EIS) has been developed by Kern et al (2017) and is currently under investigation. Besides experiments, CFD simulations are intensively used for analysis of the inner aerodynamics within the EIS.…”

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

“…Kern et al [184] managed to increase the injection mass flow rate by decreasing the injected primary mass flow rate while also utilising the ejector effect. Primary mass flow was injected from the high-pressure compressor, and it entrained an ambient secondary mass flow rate.…”

“…High-momentum fluid is recirculated from the impeller to the impeller inlet through the recirculation slot. [180] 2017 Recirculating slots CC − + + [180] 2017 Bleed slots CC 40% ±0% +10% + [181] 2017 Axial slots MC −0.7% +26.4% [182] 2017 Recirculating slots AC 0.27-0.38% ±0% + +20% [183] 2017 Injection nozzle CC 0-80% −1% +3% +40% [184] 2017 Injection nozzle AC + [185] 2017 Grooves HPT cascade 220,000 Max 4% reduction in total pressure loss [186] 2017 Injection nozzle HPT cascade 60,000 0.4% 20% reduction in total pressure loss [187] 2016 Grooves AC ±0% ±0% [188] 2016 Grooves Channel flow 2648-30,000 40% reduction in drag [171] 2016 Recirculating slots with vanes CC, Ns = 1.00 up to 20% −0.25%pt +25% +69% [171] 2016 Recirculating slots with vanes CC, Ns = 0.85 up to 20% −0.4%pt +30% +94% [189] 2016 Recirculating slots AC 0.47% ±0% +6.12% [190] 2016 Grooves AC +5.7% [191] 2016 Bleed chamber AC ±0% ±0% +3.5 . .…”