Proper Orthogonal Decomposition as a technique for identifying two-phase flow pattern based on electrical impedance tomography

Abstract

Collecting very large amount of data from experimental measurement is a common practice in almost every scientific domain. There is a great need to have specific techniques capable of extracting synthetic information, which is essential to understand and model the specific phenomena. The Proper Orthogonal Decomposition (POD) is one of the most powerful data-analysis methods for multivariate and nonlinear phenomena. Generally, POD is a procedure that takes a given collection of input experimental or numerical data and creates an orthogonal basis constituted by functions estimated as the solutions of an integral eigenvalue problem known as a Fredholm equation. By utilising POD to identify flow structure in horizontal pipeline, specially, for slag, plug and wavy stratified air-water flow regimes, this paper proposes a novel approach, in which POD technique extends the current evaluation procedure of electrical impedance tomography applied on air-water flow measurement [32] . This extension is provided by implementation of the POD as an identifier of typical horizontal multiphase flow regimes. The POD snapshot matrices are reconstructed for electrical thomography measurement domain and specific flow conditions. Direct POD method introduced by Lumley and Snapshot POD method introduced by Sirovich are applied. It is expected that this study may provide new knowledge on two phase flow dynamics in a horizontal pipeline and supportive information for further prediction of multiphase flow regime.

Vertical annular flow pattern characterisation using proper orthogonal decomposition of Electrical Impedance Tomography

“…The vertical flow map was used for the demonstration of the flow regimes obtained from the flow loop. The Red area presents the original working flow conditions [15], which was extended to theBlue area by the device reconfiguration [16]. Therefore, in the vertical pipe section, it is possible to generate slug, churn and annular flow patterns, also produce stratified, wavy, plug, slug and annular flow patterns in the horizontal pipe section.…”

“…Therefore, in the vertical pipe section, it is possible to generate slug, churn and annular flow patterns, also produce stratified, wavy, plug, slug and annular flow patterns in the horizontal pipe section. Figure 4 shows 10 slug and churn flow measurement points (variant 1-10) as references for 10 annular flow measurement points (variant [11][12][13][14][15][16][17][18][19][20] in the vertical pipe section. The flow conditions, including corresponding Reynolds numbers, are presented in Table 2.…”

Using proper orthogonal decomposition to solve heat transfer process in a flat tube bank fin heat exchanger

“…POD was also adopted to understand the flow dynamics information about the coherent structures of different energy modes. Polansky and Wang (2017) utilized the POD to identify flow structure and revealed the air-water flow regimes in a horizontal pipeline with slag, plug and wavy stratified phenomena. Zhang and Xiang (2015) proposed an efficient method based on POD to resolve the transient heat conduction problems with enough computational accuracy.…”

Experimental tomographic methods for analysing flow dynamics of gas-oil-water flows in horizontal pipeline

“…The Proper Orthogonal Decomposition method was also utilised to identify and analyse typical flow regimes in the horizontal pipeline ( Figure 3). The intention of the method for recognition of flow regime [7] using decomposition mathematical technique comes from the fact that each regime is characterised by typical dynamic behaviour. To recognise the multiphase flow dynamic structures [8], means indeed the recognition of the prevalent regime to indicate the actual flow conditions of the measurement domain.…”

“…To recognise the multiphase flow dynamic structures [8], means indeed the recognition of the prevalent regime to indicate the actual flow conditions of the measurement domain. The direct approach of Proper Orthogonal Decomposition are used to identify a typical multiphase flow instability [9]. Mathematical method, such as Wavelet Transformation and Kalman Filtering was used as a complementary techniques for detection of multiphase fluid motion and flow structures [10].…”