Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
The influence of vaneless annular passage in the performance of a centrifugal compressor with vaned diffuser
Submission Author:
Rafael Eller , SP
Co-Authors:
Rafael Eller, Elóy Esteves Gasparin, Jurandir Itizo Yanagihara, Leandro Salviano
Presenter: Rafael Eller
doi://10.26678/ABCM.COBEM2023.COB2023-0642
Abstract
Centrifugal compressors are widely applied for several industrial applications where supercritical gasses such as CO2 shows a high potential for use in power generation plants, transportation and oil industry. The contribution to oil production is through the capture and storage of greenhouse gasses by EOR (Enhanced Oil Recovery) method which consists in the injection of CO2 in depleted oil reservoirs in order to avoid its liberation to the atmosphere, increase oil production and mitigate pollution problems. In this aspect, computational fluid dynamics (CFD) simulations can be used to increase the efficiency of these machinery. One-dimensional modeling is often used to design centrifugal compressor components. However, it is not able to predict important phenomena leading to the use of 3D-CFD modeling. Centrifugal compressors have important components usually targeted for optimization such as the diffuser which is responsible for converting part of the impeller kinetic energy into static pressure (pressure recovery) and also for guiding the flow to the volute or returning channel. Diffusers can be designed with vanes to increase pressure recovery and are known as vaned-diffusers. There are several types of vaned diffusers such as conventional, vane island, channel, low-solidity vaned diffusers among others, which have been investigated in open literature. They are composed of an initial vaneless space, the vanes and the exit vaneless space. This initial vaneless space is also known as vaneless annular passage, which consists in a classical vaneless diffuser with an unbounded flow path from the impeller exit radius (R3) to the diffuser inlet radius (R2). This region is influenced by the radius ratio R3/R2 and it is a source of losses in the centrifugal compressor, highlighting its importance to further investigations. Therefore, this work investigated the influence of the vaneless annular passage in the performance of a centrifugal compressor with a vaned diffuser by variating the diffuser inlet and impeller outlet radius ratio R3/R2 in order to observe flow phenomena and its effects in loss sources and performance. For this, a preliminary geometry is created using 1D code design for the impeller and the vaned diffuser. This geometry is parametrized and a mesh is generated using GCI methods to ensure grid independence. The 3D model is numerically validated to ensure its reliability and finally simulated using Ansys 19.0 software. The metrics such as pressure recovery and isentropic efficiency have been evaluated to define alternatives for optimal designs.
Keywords
Centrifugal Compressor, Vaned Diffuser, Vanelles annular passage, CFD
