Abstract:The flow control in twin air-intakes is necessary to improve the performance characteristics, since the flow traveling through curved and diffused paths becomes complex, especially after merging. The paper presents a comparison between two well-known techniques of flow control: active and passive. It presents an effective design of a vortex generator jet (VGJ) and a vane-type passive vortex generator (VG) and uses them in twin air-intake duct in different combinations to establish their effectiveness in improv… Show more
“…The CFD results of baseline twin air-intake was validated with the experimental results reported by Paul 33 and is described in detail in Rajnath et al 16 The validation graph comprising of coefficient of static pressure recovery ( C PR ) along the normalized length ( s / C L ) of the air-intake is shown in Figure 4. It is noticed that the experimental and CFD results maintain similar trends with highest deviation reported at 10%, making it reasonable and within the acceptable limit.Figure 4.Comparison of static pressure recovery coefficient in the baseline air-intakes (Rajnath et al 16 ).…”
Section: Geometry and Modelingmentioning
confidence: 95%
“…[19][20] However, the application of these flow control techniques for internal flow fields are found in scanty. Passive devices, namely, deflectors, 21 vane-type vortex generators, [22][23][24][25] and active devices like vortex generator jets 13,26 are used in air-intake applications. However, these devices are not found appropriate in terms of meeting the controllability and zero-netmass-flow requirement.…”
Section: Introductionmentioning
confidence: 99%
“…Some of the researchers like Singh et al, 12 Paul et al 13 have also contributed in the study on flow behavior of the air-intakes. The researchers also investigated the performance of twin air-intake at supersonic operating range.…”
Ambient air is ingested into the engine of military aircrafts using the air-intake system within a limited space. The flow non-uniformity produced in the air-intake creates flow separation and total pressure loss due to the centerline curvature and area diffusion which eventually affects its performance. The current work discusses the performance of a transitional twin air-intake without and in presence of slotted synthetic jets. The synthetic jet is employed just before the inflection at a range of velocity ratio from 1 to 10 and found that for a velocity ratio of 4.0, the pressure distortion at the aerodynamic interface plane is found minimum. Hence, the other performance parameters are computed at that optimized flow condition. The outcome of the study reveal that the static pressure is recovered by 4.61%–6.64% while the total pressure loss is decreased by 59.28%–89.95% using optimized synthetic jets for a range of Reynolds numbers.
“…The CFD results of baseline twin air-intake was validated with the experimental results reported by Paul 33 and is described in detail in Rajnath et al 16 The validation graph comprising of coefficient of static pressure recovery ( C PR ) along the normalized length ( s / C L ) of the air-intake is shown in Figure 4. It is noticed that the experimental and CFD results maintain similar trends with highest deviation reported at 10%, making it reasonable and within the acceptable limit.Figure 4.Comparison of static pressure recovery coefficient in the baseline air-intakes (Rajnath et al 16 ).…”
Section: Geometry and Modelingmentioning
confidence: 95%
“…[19][20] However, the application of these flow control techniques for internal flow fields are found in scanty. Passive devices, namely, deflectors, 21 vane-type vortex generators, [22][23][24][25] and active devices like vortex generator jets 13,26 are used in air-intake applications. However, these devices are not found appropriate in terms of meeting the controllability and zero-netmass-flow requirement.…”
Section: Introductionmentioning
confidence: 99%
“…Some of the researchers like Singh et al, 12 Paul et al 13 have also contributed in the study on flow behavior of the air-intakes. The researchers also investigated the performance of twin air-intake at supersonic operating range.…”
Ambient air is ingested into the engine of military aircrafts using the air-intake system within a limited space. The flow non-uniformity produced in the air-intake creates flow separation and total pressure loss due to the centerline curvature and area diffusion which eventually affects its performance. The current work discusses the performance of a transitional twin air-intake without and in presence of slotted synthetic jets. The synthetic jet is employed just before the inflection at a range of velocity ratio from 1 to 10 and found that for a velocity ratio of 4.0, the pressure distortion at the aerodynamic interface plane is found minimum. Hence, the other performance parameters are computed at that optimized flow condition. The outcome of the study reveal that the static pressure is recovered by 4.61%–6.64% while the total pressure loss is decreased by 59.28%–89.95% using optimized synthetic jets for a range of Reynolds numbers.
“…It has been demonstrated that active VGs provide similar benefits as passive VGs, but with a major added advantage: when they are not functional, there is no increment in the parasitic drag (Paul et al 2013). Despite the clear benefits of active VGs, different configurations of vane-type VGs are still a commonly implemented solution on wind turbine blades.…”
Wind turbines are complex energy conversion fluid-flow machines which entail coupled aero-mechanical issues. From an aero-acoustical point of view, wind turbine blades present two main problems: first, a reduced aerodynamic performance due to flow separation, and second, the level of noise emissions. Flow separation appears on the blade as a result of high angles of attack causing a decrease in the aerodynamic efficiency. In this chapter, the application of rod vortex generators (RVGs) to control and decrease the flow separation-by the creation of streamwise vorticity on the blade-is presented. The NREL Phase VI wind turbine rotor and the S809 airfoil are used as reference cases. The validation of NREL Phase VI model rotor against experimental data is found to be satisfactory. A study into the effects of RVGs' chordwise location and spanwise distance is presented for selected cases and a range of inflow conditions. It is shown that the proposed RVGs lead to an improvement of the aerodynamic performance, and can be successfully applied by the wind energy industry.
IntroductionThe wind energy sector has experienced rapid growth in the last few decades. The developments in the materials science, engineering and allied fields have ushered in turbines of increasing sizes; turbines with rotor diameters of up to 160 m (Vestas V164 8 MW) have been developed, and the current trend of increasing sizes is expected to continue in the future (Bak et al. 2012).The increasing sizes of wind turbines pose new challenges for engineers. One particular challenge is that large rotor dimensions result in non-uniform inflow conditions along the blade span-which leads to increased flow separation even after the application of traditional flow control approaches. As a consequence of
“…Nowadays, more and more techniques of chaos synchronization were proposed, such as active control [2][3][4], backstepping control method [5][6][7][8], linear error feedback control [9][10][11], adaptive control [12][13][14][15][16], and sliding mode control [17][18][19][20].…”
A novel bioinspired control strategy design is proposed for generalized synchronization of nonlinear chaotic systems, combining the bioinspired stability theory, fuzzy modeling, and a novel, simple-form Lyapunov control function design of derived high efficient, heuristic and bioinspired controllers. Three main contributions are concluded: (1) apply the bioinspired stability theory to further analyze the stability of fuzzy error systems; the high performance of controllers has been shown in previous study by Li and Ge 2009, (2) a new Lyapunov control function based on bioinspired stability theory is designed to achieve synchronization without using traditional LMI method, which is a simple linear homogeneous function of states and the process of designing controller to synchronize two fuzzy chaotic systems becomes much simpler, and (3) three different situations of synchronization are proposed; classical master and slave Lorenz systems, slave Chen's system, and Rossler's system as functional system are illustrated to further show the effectiveness and feasibility of our novel strategy. The simulation results show that our novel control strategy can be applied to different and complicated control situations with high effectiveness.
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