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A Study on the Channel and Gap Flow Simulation For Electrical Discharge Micro-Drilling of Inconel 718 Superalloy

Machno Magdalena, Trajer Marcin, Czeszkiewicz Adrian, Żurawka Paulina

Advances in Science and Technology. Research Journal

2024

Vol. 18, no 2

159--176

The process of electrical discharge micro-drilling (micro-EDD) of micro holes is used in the aviation, automotive and biomedical industries. In this process, an important issue affecting the stability and efficiency of the process is the flow of the working fluid through the tool electrode channel and the front and side gap areas. Because tool electrodes have diameters below 1 mm. Many factors present in the EDM-drillig process occurring on a micro scale mean that a full explanation of the phenomena affecting the process is limited. The solution is to analyze the phenomena in the process based on the results of numerical simulations, which are based on real measurements. The aim of this work is to analyze the flow of de-ionized water through a brass single-channel electrode with a channel diameter of 0.11 mm and a front and side gap. The liquid flow was analyzed for various variants (with and without cavitation, with added rotation of the tool electrode, with and without surface roughnes with material particles). In simulation, it is important to gradually increase the complexity of the model, starting with the simplest model and gradually adding further phenomena. Analysis of the simulation results showed a significant impact on the liquid flow of cavitation, as well as the presence of vortex gaps in some areas, which have a significant impact on the process of drilling micro holes.

CFD Study of Base Drag of the Grot Rocket

Sahbon Nezar, Michałów Maciej, Murpani Siddharth, Żurawka Paulina, Kaczmarek Kacper

Transactions on Aerospace Research

2023

Nr 2 (271)

1--16

Propulsion system operation is known to affect the aerodynamic characteristics of rockets. Specifically, the net axial force acting on a rocket in flight cannot be precisely obtained by combining the static thrust with drag values computed for a rocket with an inactive motor. One of the main reasons for this is the influence of motor operation on pressure at the base of the rocket. The aim of this paper is to investigate the effect of motor operation on the aerodynamic parameters of the Grot sounding rocket developed by the Students’ Space Association, Warsaw University of Technology. The study consists of two series of axisymmetrical computational fluid dynamic simulations of flow around the rocket - one with the motor being non-operational and the other with active thrust. In the post-processing phase, the axial force acting on various components of the rocket is computed, with an emphasis on the base and nozzle exit sections. Quantitative and qualitative differences between the cases with and without active thrust are highlighted and discussed. The obtained results are compared to a semi-empirical model found in the literature. Finally, a semi-empirical base drag model is proposed for use in Grot flight simulation.