Design modification of two-dimensional supersonic ejector via the adjoint method

[Display omitted] •Adjoint method is proposed for design modification of a 2D supersonic gas ejector.•Adjoint method simultaneously modified three main geometrical sections.•ER was enhanced up to 37.17% by the design modification compared to the baseline.•The modified geometry via adjoint method was simplified.•Further investigation on Hms for the simplified geometry obtained ER up to 0.455. A numerical investigation of a design modification of a two-dimensional supersonic gas ejector was undertaken via an adjoint method, with a focus on enhancing the performance of the ejector. Maximization of the secondary mass flow rate was used as an objective function. The entrance geometry and throat height of the primary nozzle were fixed, but the other geometries were allowed to vary during the design modification. The shape of the divergence of the primary nozzle, the nozzle exit position (NXP), and the entrance region of the mixing chamber were modified simultaneously using the adjoint method. The height of divergent section of primary nozzle (Hne), NXP, and the inlet height of the mixing chamber (Hmi) were enlarged by about 13.33%, 27%, and 49%, respectively, resulting in an entrainment ratio (ER) that was enhanced by about 37.17% compared to that obtained for the baseline geometry. Two simplified geometries from the adjoint modification were suggested, and have the same performance with the adjoint-modified geometry. Further investigation was performed by varying the height of the straight section of the mixing chamber of the simplified geometry. The results show that the ER increased by about 46.77% compared with that obtained using the simplified geometry.