Flow control in the S-duct based on the DBD plasma actuator
Creators: name:  F. JIANG 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: FLOW CONTROL
AEROSPACE

description: Flow control in the S-duct based on the DBD plasma actuator Jiang Fan1, Kostantinos Kontis2 and Craig White3 School of Engineering, James Watt South Building, Glasgow, G12 8QQ 1PhD student: 2288394j@student.gla.ac.uk 2Professor: Kostas.Kontis@glasgow.ac.uk 3Lecturer: Craig.White.2@glasgow.ac.uk Abstract: Compared with the straight intake, the most apparent feature of the S-duct is its massive curved geometry. The boundary layer in the S-duct cannot entirely fit the inner tube wall, resulting in flow separation regions. Flow separation increases the airflow instability (distortion and swirl) and reduces the total pressure recovery coefficient. The purpose of this research is to study the performance of AC-DBD plasma flow control in the S-duct under the conditions of large Reynolds number (200k-300k) and low speed (Inlet velocity: 17-19 m/s). The main control parameters are plasma actuator configuration, frequency, voltage, duty cycle, modulation frequency. Introduction: As a kind of intake, s-duct has many advantages that conventional straight ducts cannot achieve. Because of the curvature of the S-duct itself, the air flows the same distance, the overall length of the S-duct can be designed to be shorter [1][2]. Space is used more efficiently, and considerable weight can be saved. According to the calculation of Chen et al. (2012), they find if the fuselage can be shortened a diameter of the inlet, the net weight is only 85% of the original. In addition, the s-shaped inlet can effectively reduce external noise and radar characteristics [2][3]. These advantages make S-duct very suitable for aircraft with high stealth requirements. However, although S-duct has benefits for the big angle of attack and stealth design, it also brings new problems with engine compatibility, which will directly influence flight performance [3][4]. Flow separation is unavoidable in the S-duct because of the vast curvature, and the accompanying flow separation loss can significantly reduce the total pressure recovery coefficient. This causes the net thrust to drop. In addition, distortion and swirl will also reduce the net thrust of the engine and may even induce engine surge. Flow separation is unavoidable in S-pipes, and the accompanying flow separation losses can significantly reduce the total pressure recovery coefficient. This time results in a drop in the engine\'s net thrust. In addition, distortion and distortion will also reduce the net thrust of the engine and may even induce engine surge. The current work will use the AC-DBD plasma actuator, an active flow control method, to improve flow separation in the S-duct; and study how plasma actuator configuration, frequency, voltage, duty cycle, modulation frequency and so on influence flow control. In this research, the S-duct geometry is from Wellborn [5]. Figure 1 shows its schematic. The duct centerline consists of two planar arcs. Radius R1 = R2 = 102.1cm and subtended angle is 30. The length of the duct is five times D1. Figure 2 shows the full experimental S-duct model and relevant geometry parameters. Figure 3 shows two groups of comparative experiments. There are five plasma actuators installed following flow direction. The location is Axial: 0.4 L/Dthroat 1.2, Circumferential: 160 ? 200. Plasma actuators are off in the baseline group. Figure 1: S-shaped duct geometry [6] Figure 2: Full experimental S-duct model Baseline 1 17kv_4khz_1 Baseline 2 17kv_4khz_2 Figure 3: Stagnation pressure at AIP Reference: [1] Yang, H., Li, F., Song, Y., Sun, B. (2012). Numerical investigation of electrohydrodynamic (EHD) flow control in an s-shaped duct. Plasma Science and Technology, 14(10), 897. [2] Vaccaro, J. C., Elimelech, Y., Chen, Y., Sahni, O., Jansen, K. E., Amitay, M. (2015). Experimental and numerical investigation on steady blowing flow control within a compact inlet duct. International Journal of Heat and Fluid Flow, 54, 143-152. [3] Chen, Z., Wang, J. (2012). Numerical investigation on synthetic jet flow control inside an S-inlet duct. Science China Technological Sciences, 55(9), 2578-2584. [4] Reichert, B. R. U. C. E. A., Wendt, B. R. U. C. E. J. (1994, February). Improving diffusing S-duct performance by secondary flow control. In 32nd Aerospace Sciences Meeting and Exhibit (p. 365). [5] WELLBORN, S., REICHERT, B., OKIISHI, T. (1992, July). An experimental investigation of the flow in a diffusing S-duct. In 28th joint propulsion conference and exhibit (p. 3622). [6] Wojewodka, M. M., White, C., Shahpar, S., Kontis, K. (2018). A review of flow control techniques and optimisation in s-shaped ducts. International Journal of Heat and Fluid Flow, 74, 223-235.