APPLICATION OF AN ENHANCED 1D NETWORK MODEL TO CALCULATE THE FLOW PROPERTIES OF A PRE-SWIRL SECONDARY AIR SYSTEM

摘要

Former investigations [10] were focused on the design point of the secondary air system. This paper discusses further enhancements to the modelling to describe the flow in the pre-swirl cavity more precisely at off design flow conditions. Special focus was drawn to mixing of the pre-swirl nozzle flow with the flow in the cavity. Together with the description of the friction losses and the surging effects of the boundary layers with new modules in a 1D network model the flow in the mixing region is now appropriately reproduced. 3D CFD investigations were used for calibration of the correlation approach. The 1D network model so enhanced was then used to simulate the flow in the pre-swirl test rig at the University of Duisburg-Essen over a wide range of operating conditions. A comparison of the experimental results from the test rig to the results of the enhanced 1D network model reveals that the crucial parameters can be now determined over the complete operating range of the test rig. It is demonstrated that the accuracy of the estimated pressure ratio, the temperature and the swirl ratio of the pre-swirl system is now much better.