Geometric parameters effect of ejector with curvilinear section of mixing chamber on its characteristic

DOI: 10.34759/vst-2019-4-166-173

Аuthors

Kartas S. S.^*, Panchenko V. I.^**, Aleksandrov Y. B.^***

Kazan National Research Technical University named after A.N. Tupolev, 10, Karl Marks str., Kazan, 420111, Russia

*e-mail: salar.saber29@mail.ru
**e-mail: panchenkovi@rambler.ru
***e-mail: Alexwischen@rambler.ru

Abstract

Ejector is the simplest device without moving parts for liquids, gas, and other media moving. Power transfer from one stream to the other proceeds by their turbulent mixing. Very often, injector is employed to maintain continuous airflow in a duct, or a premise, thus performing a fan role. It is used also for jet engines testing. The exhaust stream flowing from the jet nozzle draws in the air from the shaft into the ejector, ensuring thereby the premise ventilation and engine cooling.

Over the past 60 years, plenty of studies has been performed on ejectors as a part of jet engines, which purpose consisted in increasing engine thrust, and reducing fuel consumption, jet noise and output temperature.

In modern conditions, these devices are used in various fields, such as aircraft and machine building, firefighting equipment, and as pumps, compressors, and mixers at oil tank farms.

In general, the described ejector structures include straight-line mixing chambers. Employing a curvilinear section of mixing chamber, which allows improve the ejector parameters, may be suggested as an option of such ejectors. An option of the ejector of this kind consists of a high-pressure flow nozzle, a low-pressure flow nozzle, mixing chamber, and diffusor. With this, the initial section of the mixing chamber is curvilinear.

The disadvantage of this ejector is certain difficulties in manufacturing curvilinear surfaces of nozzles and initial section of the mixing chamber. The advantage of this ejector consists in average velocity reduction of the active jet at the mixing chamber inlet, and, as a consequence, mixing losses reduction.

The article presents the results of numerical calculation of the  characteristics of curvilinear ejectors with F₁/F₂ = 1 geometric parameter (elbows and bends) at relative sizes of R/a = 1; 2. These results revealed that with the same ejection coefficients, the relative pressure drop is greater for a curvilinear ejector with a relative radius of R/a = 2. The numerical calculation was performed in a stationary setting using the Fluent program and the k-e RNG turbulent viscosity model. Based on preliminary calculations and the grid independence analysis of the obtained results, the grid models were selected.

Keywords:

ejector, curvilinear section of mixing chamber, geometric parameters, ejection coefficient

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