Investigation of High-Speed Flow Control from CD Nozzle Using Design of Experiments and CFD Methods
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RESEARCH ARTICLE-MECHANICAL ENGINEERING
Investigation of High-Speed Flow Control from CD Nozzle Using Design of Experiments and CFD Methods Abdul Aabid1
· Sher Afghan Khan1
Received: 18 June 2020 / Accepted: 15 October 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract In high-speed fluid dynamics, the control of base pressure finds many engineering applications such as automobile industry and defense applications. Several studies have been reported on passive control using devices like cavities, ribs, aerospikes, etc. in the last three decades. Therefore, the present research focuses on active control uses the microjets in the form of an orifice of a 1 mm diameter to inject the air in the base flows and located at base area of 90° intervals as a control mechanism. Since the air is drawn from the main settling chamber, the NPR will be the same as the respective NPRs used for tests. Experiments were conducted in the presence and absence of the microjets for area ratio 3.24 and L/D ratios from 10 to 1 at Mach numbers 1.87, 2.2, and 2.58. The parameters were optimized using the design of experiments (DOE) approach. Three parameters have been selected for the flow and the DOE. An L9 orthogonal array, multiple linear regression, and confirmation tests were performed to analyze the experimental results. The developed models are statistically suitable and accomplished in producing reasonable predictions for both cases. Besides, a computational fluid dynamics method has been utilized and validated by the experimental results. The k–1 turbulent model is used to analyze the simulation results. According to the present results, it is evident that for a given parameter, an L/D ratio is the most significant impacting to a maximum increment or decrement of a base pressure. Keywords Base pressure · Supersonic flow · CFD · Mach number · Microjet control · DOE
List of Symbols Pb Base pressure Pw Wall pressure Pa Atmospheric pressure M Mach number ρ Density k Turbulent kinetic energy μ Dynamic viscosity
CFD CD DF DOE FVM L/D MIS NPR PDE PRV RANS
Computational fluid dynamics Convergent–divergent Degree of freedom Design of experiments Finite volume method Length-to-diameter ratio Mesh independence study Nozzle pressure ratio Partial differential equation Pressure regulating valve Reynolds average Navier–Stokes
Subscripts 2D BFS
B 1
Two-dimensional Backward-facing steps
Abdul Aabid [email protected]; [email protected] Department of Mechanical Engineering, Faculty of Engineering, International Islamic University Malaysia, PO Box 10, 50728 Kuala Lumpur, Malaysia
1 Introduction Sudden expansion is a common problem for numerous fields in the automobile and aerospace industries. The sudden increase in the area leads to separation of the flow into two regions: One is the central flow region, and the second is the separated or wake region. After termination of the shear layer from the nozzle, the flow is reattached with the duct
123
Arabian Journal for Science and Engineering
Fig. 1 Flow expa
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