Optimization and improvement of ac resistance calculation method for multi-phase parallel-wiring cables

Parallel-wiring cables are often used in multi-phase AC aircraft Electrical Power Systems(EPSs).However,it complicates the ac resistance estimation.To solve this issue,an analytical resistance calculation method for parallel-wiring cables in multi-phase EPS was proposed.Firstly,the existing calculation formula of proximity factor was optimized,and the calculation error was reduced from 16%to 2%when two conductors are close to each other.Afterwards,the superposition effect on current density distribution between multi-conductors was considered based on orthogonal decomposition method,and the position of the equivalent charged points were easily determined.Finally,the ac resistance calculation formula was derived according to characteristics of parallel-wiring strategy,and the general ac resistance calculation methods of multi-phase parallel-wiring cables were presented.The proposed approach considerably enhances the applicability of ac resistance analytical calculation method for multi-conductor cables.Thanks to the accuracy of the proposed method,it can be used in many cases to avoid case-by-case simulation work and facilitate efficient system design and analysis.

The Finite Element Analysis for Parallel-wire Capacitance Probe in Small Diameter Two-phase Flow Pipe

This paper presents a novel capacitance probe, i.e., paraUel-wire capacitance probe （PWCP）, for two-phase flow measurement. Using finite element method （FEM）, the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters. Then, the response of PWCP for the oil-water stratified flow is calculated, and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness, and is almost independant of the angle between the oil-water interface and the sensor electrode. Finally, the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.

Prediction of curved oil–water interface in horizontal pipes using modified model with dynamic contact angle

In this study,interface shapes of horizontal oil–water two-phase flow are predicted by using Young-Laplace equation model and minimum energy model.Meanwhile,the interface shapes of horizontal oil–water twophase flow in a 20 mm inner diameter pipe are measured by a novel conductance parallel-wire array probe(CPAP).It is found that,for flow conditions with low water holdup,there is a large deviation between the model-predicted interface shape and the experimentally measured one.Since the variation of pipe wetting characteristics in the process of fluid flow can lead to the changes of the contact angle between the fluid and the pipe wall,the models mentioned above are modified by considering dynamic contact angle.The results indicate that the interface shapes predicted by the modified models present a good consistence with the ones measured by CPAP.