Mitigation of oscillatory instability in turbulent reactive flows: A novel approach using complex networks

Abstract

We present a novel and an efficient way to mitigate oscillatory instability in turbulent reactive flows. First, we construct weighted spatial correlation networks from the velocity field obtained from high-speed particle image velocimetry. Using network measures, we identify the optimal location for implementing passive control strategies. By injecting micro-jets at this optimal location, we are able to reduce the amplitude of the pressure oscillations to a value comparable to what is observed during the state of stable operation. This approach opens up new avenues to control oscillatory instabilities in turbulent flows.

Suppression of thermoacoustic instability by targeting the hubs of the turbulent networks in a bluff body stabilized combustor

“…Further, we note that we are able to identify two optimal locations based on the vorticity network analysis as compared with the single optimal location, which we had identified using the velocity correlation network analysis (Krishnan et al. 2019 a ; Unni et al 2021). Hence, we can say that the vorticity network analysis used in the current study is better compared with the correlation network analysis performed by us in our earlier study (Krishnan et al.…”

“…Recently, we have used network theory to identify the optimal location to implement a passive control strategy (Krishnan et al. 2019 a ). We constructed weighted spatial correlation networks from the velocity field and used network measures to identify the optimal location for secondary air-jet injection.…”

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Figure 13.( a ) The spatial distribution of the node strength during thermoacoustic instability from the weighted correlation network analysis performed in Krishnan et al. (2019 a ). ( b ) The spatial distribution of the node strength of the phase averaged turbulent network during thermoacoustic instability and ( c ) the probability distribution of the node strength of the phase averaged turbulent network.

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“…Krishnan et al. (2019 a ) used a weighted correlation network analysis to identify an optimal location in the flow field to implement a passive control strategy to mitigate thermoacoustic instability. Recently, we investigated the spatiotemporal dynamics of acoustic power sources by constructing time-varying spatial networks during the different dynamical states of combustor operation (Krishnan et al.…”

Identifying vortical network connectors for turbulent flow modification

“…There have also been recent advances in using complex network analysis for turbulent flow control. Krishnan et al (2019a) have used spatial correlation networks to mitigate oscillatory instabilities in turbulent reactive flows by identifying appropriate locations for passive control strategies through various network measures. Also, Yeh et al (2020) have utilized time-evolving vortical networks to identify dynamically relevant pathways to modify turbulent flows by combining formulations of Katz centrality and resolvent analysis.…”