Air-air Ejectors Research Articles

Air Ejector Analysis in Extended Operational Perimeter for Control Oriented Simulation of Bleed-Air Aircraft Systems

The integration of large size Ultra High Bypass Ratio (UHBR) engines introduces new restrictions of space for their integration with the aircraft wing. Under this scenario, a reduction of the size of the bleed air system and particularly of the pre-coolers is requested. The current research aims to introduce air-air ejectors as a potential solution. A combined methodology based on experimental and CFD analyses is proposed to obtain physical insights and validation material for the development of a robust and accurate lumped model, capable of simulating the static and dynamic ejector behaviour in normal and abnormal conditions. In this paper, an overview on the performed initial activities on the dynamic aspects is provided.

Study of the Configuration and Performance of Air-Air Ejectors based on CFD Simulation

This paper describes a numerical study of gas-gas ejector performance for different operating conditions and geometrical configurations. The performance of ejector obtained based on a simulation procedure of linearized and axisymmetric subsonic and supersonic flow using Fluent Package. A conventional finite-volume scheme utilized to solve two-dimensional transport equations with the standard k-ω SST turbulence model. The model is solved in three regions namely, the primary flow nozzle, the secondary flow channel, and the region of interaction between the supersonic nozzle jet and the secondary flow. The effect of gas motive pressure the mixing part and tail section (pipe or diffuser) geometry on the ejector performance are studied. The computational results are validated using published experimental data with acceptable agreements. The numerical results indicate that the ejector geometry has a pronounced effect on the flow parameters (i.e., pressure and gas velocity) and the ejector performance. In addition, predicted numerical results indicate that when the motive-stream velocity exceeds the speed of sound, shock waves are unavoidable inside ejectors and that shock wave pattern in mixing part has a dominant effect on ejector performance. In addition, the results indicate that the shock location inside the nozzle and the separation point are affected by the motive pressure. The results show also that configuration with convergent-divergent mixing section is much better for mixing process than the other tested configurations.

Experimental Study of Oblong Exhaust Ejectors With Multiring Oblong Entraining Diffusers

This paper presents experimental data for the performance of two oblong, straight, air-air ejectors with four-ring oblong entraining diffusers. The effects of inlet swirl angle, nozzle diameter, and flow temperature on the ejector pumping, backpressure, wall pressure distribution, diffuser pressure recovery, and surface film cooling effectiveness were studied. The experiments were carried out on a hot gas wind tunnel that could provide primary mass flow rates up to 2.2kg∕s at ambient temperature and 1.8kg∕s at 500°C. Velocity, pressure, and temperature were measured in the annulus upstream of the primary nozzle, on the mixing tube and diffuser walls, at the diffuser gap inlets, and at the diffuser exit. A comparison between the performance of the oblong ejector and a round ejector indicated that for a short length ejector, the oblong ejector provided better overall performance in terms of pumping and velocity and temperature distributions.