Plasma Synthetic Jet Actuators for the Control of Transonic Shock Wave Boundary Layer Interaction

Lead Research Organisation: City University London
Department Name: Sch of Engineering and Mathematical Sci


The plasma synthetic jet actuator (PSJA) is a type of active flow control device. It is able to generate powerful jet at high repetition rate. The PSJA has promising control capability in high-speed flow applications, especially in alleviating the adverse effects of shock wave boundary layer interaction. Despite the significant improvements made so far, the PSJA still suffers problem such as the requirement of multiple high-voltage power units if a PSJA array is under use. Very recently, the novel voltage relay circuit (VRC) is proposed through the principal investigator (PI)'s collaborative project under the joint funding from the Royal Society and Natural Science Foundation of China. The new VRC concept allows multiple PSJAs to be driven through one single high-voltage power unit, which is a technological breakthrough leading to the practical application of PSJA.

The VRC-driven PSJA array is thus proposed as the flow control method to manipulate the transonic shock boundary layer interaction (TSWBLI), which underpins further improvement of the performances of aircraft and its propulsion system. In the UK, the Aerospace Technology Institute (ATI) explicitly includes 'pushing the shock buffeting boundary' as a strategically important target in the development plan for UK aerospace industries for the coming decade. The research outcome will thus contribute to the ATI target and help consolidate the leading position of UK aerospace industry.

The preliminary experiment carried by the PI and his collaborator reveals that the VRC-driven PSJA array is effective in shock modulation. Moreover, the transonic wind tunnel at City, University of London is being strengthened to experiment aerodynamic problems in the transonic regime through the support of National Wind Tunnel Facility. Therefore, funding is applied to implement the VRC-driven PSJA array into the control of TSWBLI. The research outcome is going to exert direct impact to the UK aerospace sector. Although the VRC-driven PSJA is used in the transonic flow in the present project, it is also readily useful in supersonic applications where shock wave boundary layer interaction dominates.

Planned Impact

The aerospace industry is the powerhouse to UK economy. The present project focuses on mitigation of the adverse effects caused by transonic shock wave boundary layer interaction (TSWBLI) by means of plasma synthetic jet actuators (PSJAs). The control outcome will lead to aircraft wave drag reduction and eventually fuel saving. This project will further contribute to "delaying buffeting onset boundary", one of the targets proposed by the Aerospace Technology Institute, aiming at strengthening UK's leading position in the global aerospace industry. Apart from its importance to the aircraft, TSWBLI is also critical to the gas turbine, especially when high blade loading is adopted in the state-of-art compressor and turbine design. Therefore, the project will also impact the propulsion industry. Alleviation of TSWBLI on the aircraft and its propulsion system will improve their performances, such as a higher cruise speed and a better fuel efficiency. All these improvements will not only make the UK aerospace sector stronger and more competitive but also benefit the public, as people will arrive their destination quicker and live in an environment with less pollution.

The present project also has significant academic impacts. The PSJA array under use will be driven by the novel voltage relay circuit (VRC). The VRC breaks through the long-lasting driving unit issue in PSJA technology and allows driving PSJA array by one single power supply. The VRC technique matured through this project will impact the on-going research on PSJA technology. The VRC-driven PSJA array is experimented to control the TSWBLI in this project, it will also be used by researchers for other high-speed flow control applications, such as supersonic shock wave boundary layer interaction.

The proposed research is in the initial phase of the research roadmap (refer to Pathways to Impact), and it will establish a solid foundation for the later stage research. A consortium of several universities and industries will be formed throughout the roadmap. This consortium will be able to make a significant impact in the areas of PSJA and transonic aerodynamics with an emphasis of TSWBLI.

This project will use the transonic wind tunnel at City, part of the National Wind Tunnel Facility (NWTF). In return, the project outcome will showcase UK's excellence in aerodynamic research, which is the objective of NWTF project.

This project will impact the link between BAE Systems and City, University of London. BAE has established the BAE Systems Chair Professorship in the principal investigator (PI)'s department in 2015, and it is very supportive of this research. This project will strengthen the partnership between City and BAE on research, and accelerate the project impact.

The research will also impact UK-China collaboration in scientific research. This project takes full advantage of the PI's Royal Society-Natural Science Foundation of China project and receives support from the PI's project partner in Xi'an Jiaotong University. The success of this project will allow further in-depth collaboration between the PI and his partner in China. More importantly, it will support the governmental initiative in encouraging international research collaboration.

Finally, but not least, the present project under the support of EPSRC will build a world-leading research group in high-speed flow control with strong industrial support and international link.


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Description Some preliminary observations on the simulation data of the shock wave control in shock wave boundary layer interaction reveals the new mechanism: shock-shock interaction, which was previously thought the thermal displacement effect.
Exploitation Route The paper on this new mechanism is being prepared.
Sectors Aerospace, Defence and Marine,Energy,Transport

Description The plasma actuator under investigation is still in the lab phase. But BAE Systems, the project partner, is very interested in this technology. Moreover, it can be potentially used in controlling the flow in Organic Rankine Cycle, which is an efficient energy generation cycle.
Sector Aerospace, Defence and Marine,Energy,Transport
Title Converged Schlieren 
Description Novel use of the very large data ensemble delivered by high-speed schlieren has been developed. The new so-called converged schlieren makes full use of the large schlieren image dataset, which ensures the convergence of the schlieren intensity field and its root-mean-square value. The converged RMS value has been demonstrated being able to reveal flow structures which are not immediately available in the raw schlieren images. A paper on this method has been submitted to AIAA Journal, a recommendation for publication with minor correction was suggested. Revision on this paper is ongoing and is to be submitted for the second review. 
Type Of Material Improvements to research infrastructure 
Year Produced 2018 
Provided To Others? Yes  
Impact This new method has been reported in the Lisbon conference, which is the leading conference for optical flow measurement. Great attention has been received there and afterwards. 
Title Experimental Data 
Description The database include the schlieren visualization and velocity field measured by particle image velocimetry. They are available in PI's researchgate profile. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact According to the data of Research Gate, the number of views of the data increase, suggesting attention has been received. 
Description Collaboration with Prof Yun Wu from Xi'an Jiaotong University in China 
Organisation Xi'an Jiaotong University
Country China 
Sector Academic/University 
PI Contribution My team and Prof Wu's team from XJTU has worked closely on the plasma actuator and shock wave boundary layer interactions. I, myself, visited Prof Wu's lab in Xi'an Jiaotong University in January 2019. I also co-supervised two PhD students in Prof Wu's team. I am committed to providing training on advanced optical measurement techniques for Prof Wu's team. So far, we have published 6 journal articles since 2016.
Collaborator Contribution As agreed in the support letter, Prof Wu's team made a High-Voltage power supply for this project. I also received training on the use of this power supply. Thanks to Prof Wu's commitment, plasma actuator is in full operation in my lab in London.
Impact A total of 6 research articles have been published in established international journals with high impact: 1. Gan T, Wu Y, Sun Z, Jin D,Dai H, Li Y, Shock wave-boundary layer interaction controlled by surface arc plasma actuators, Physics of Fluids, 30:055107, 2018. 2. Tang M, Wu Y, Wang H, Guo S, Sun Z, Shen J, Characterization of transverse plasma jet and its effects on ramp induced separation, Experimental Thermal and Fluid Science, 66: 584-594, 2018 3. Zhang Z, Wu Y, Sun Z, Song H, Jia M, Zong H, Li Y, Experimental research on multichannel discharge circuit and multi-electrode plasma synthetic jet actuator, J Physics D, 50(16): 165205, 2017 4. Zhang Z, Wu Y, Jia M, Song H, Sun Z, Zong H, Li Y, The multichannel discharge plasma synthetic jet actuator, Sensors & Actuators A, 253(1): 112-117, 2017. 5. Zhang Z, Wu Y, Jia M, Song H, Sun Z, Li Y, MHD-RLC discharge model and the efficiency characteristics of plasma synthetic jet actuator, Sensors & Actuators A, 261:75-84, 2017 6. Zhang Z, Wu Y, Jia M, Song H, Sun Z, Li Y, Modeling and optimization of the multichannel spark discharge, Chinese Physics B, 26(6):065204, 2017.
Start Year 2016
Description School visit (London) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact About 50 students from Sixth-Form colleges (including Woodhouse College, University College School) each time. Most of them made the decision to study aeronautical engineering in university. My talks on my research project inspired a lot of young students.
Year(s) Of Engagement Activity 2018,2019