In this study, a single feedback loop oscillator with two outlet channels is numerically studied. In order to solve the governing equations, the commercial software of Ansys-Fluent 16.0 is used. A set of CFD simulations is performed for a 2D and turbulent flow using hybrid DES model. The results of a simple parametric study investigating the effects of five geometrical parameters such as splitter distance, angle between outlet channels, feedback loop width and different shape of splitter and feedback loop on the flow-switching frequencies produced in single feedback loop oscillators are reported. It can be observed that the 2D simulation results, which are obtained using DES method, showed more appropriate outcomes compared to various RANS models. Moreover, by changing the oscillator's geometric parameters, there will be an increase in switching jet frequency up to 25% which occurs in certain conditions. The change in the splitter distance from feedback loop showed the most variations after examining the geometric parameters in which the frequency is reduced from 83 to 38 Hz by decreasing the so-called parameter. Results also showed that the increase in outlet channel angle up to 18 degrees initially cause an increase in the frequency and then it is followed by a reduction. After investigating the change in the feedback loop width, it is concluded that by increasing the feedback loop width to 4 mm, the outlet frequency of the device increased primarily and followed by the considerable reduction. Also, the obtained frequency by the oscillator with horizontal elliptic loop is 25% higher than the circle feedback loop oscillator. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.