Numerical investigation of circulation control applied to flapless aircraft

Abstract

<jats:sec> <jats:title content-type="abstract-subheading">Purpose</jats:title> <jats:p>The purpose of this paper is to investigate the equivalent control authority of the conventional and circulation control (CC) wing of the aircraft and assess the energy expenditure and aerodynamic efficiency of the CC wing.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title> <jats:p>Four target cases with different flap deflection angles θ are set in advance for the conventional wing, and then a series of cases with different jet momentum coefficients <jats:italic>Cμ</jats:italic> are set for the CC wing. The lift, drag and momentum coefficient curves of the CC wing are compared to those of the four conventional wing cases. The curves with the best agreement are selected to establish the corresponding relation between <jats:italic>θ</jats:italic> and Cμ. The energy expenditure of the CC system is analyzed. The concept of equivalent lift-to-drag ratio for the CC wing is introduced to compare the aerodynamic efficiency with the conventional wing</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Findings</jats:title> <jats:p>The control authority of the conventional wing at <jats:italic>θ</jats:italic> = 0º, 10º, 20º, 30º are equivalent to the control authority of the CC wing with <jats:italic>Cµ</jats:italic> = 0.0, 0.005, 0.009 and 0.012. The CC system is more efficient at small <jats:italic>Cµ</jats:italic> than large <jats:italic>Cµ</jats:italic>.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Practical implications</jats:title> <jats:p>This study could contribute to the application of the CC system on flapless aircrafts.</jats:p> </jats:sec> <jats:sec> <jats:title content-type="abstract-subheading">Originality/value</jats:title> <jats:p>The corresponding relation between <jats:italic>θ</jats:italic> and <jats:italic>Cµ</jats:italic> is established by matching the equivalent control authority between the conventional wing and CC wing.</jats:p> </jats:sec>

Numerical study of the yaw control of flapless aircraft

“…The pressure ratio (PR) is defined as the ratio of the total pressure at the jet inlet over the static pressure of the freestream. Numerical method validation and grid independency study have been done by Fu et al (2020).…”

“…The trailing edge cutting method is used to change the wing’s trailing edge of the model with mechanical control surfaces into the Coanda surface to obtain the flapless aircraft model, as shown in Figure 2. The main design parameters of CC airfoil are given by Fu et al (2020).…”

“…All numerical cases in this paper are solved by ANSYS CFX , and the turbulence is solved by the SST k-ω turbulence model in the RANS method and all cases are calculated with the high-resolution scheme. The main parameter used in CC is dimensionless coefficient – jet momentum coefficient C μ – which is defined by Fu et al (2020). The pressure ratio (PR) is defined as the ratio of the total pressure at the jet inlet over the static pressure of the freestream.…”

“…Although many researchers have done a lot of research on the flapless aircraft, CC has not been applied to the aircraft’s attitude control. It has been proved that CC can replace the flaps and ailerons to realize the lift increase, roll (Hoholis et al , 2016; Forster and Steijl, 2016) and pitch control (Fu et al , 2020), but the research on yaw control is not mature. On the aircraft with mechanical control surfaces, the yaw control is mainly realized by the deflection of the rudders on the vertical tails.…”

Power performance enhancement of vertical axis wind turbines by a novel gurney flap design

“…Figure 12 shows the compression of the streamlines around the standard and angled gurney flap. The standard gurney flap has a higher pressure intensity than the angled gurney flap although, higher pressure intensity enhances the flow force on the front surface of the gurney flap and increases the fatigue in Fu et al, 2020). Furthermore, strong vorticity just behind the standard gurney flap makes the pressure gradient on the upper surface more negative (Ghandi et al, 2020).…”