A Flow Control Study of a Simplified, Oscillating Truck Cabin Using PANS

Abstract

This work presents an application of the partially averaged Navier–Stokes (PANS) equations for an external vehicle flow. In particular, the flow around a generic truck cabin is simulated. The PANS method is first validated against experiments and resolved large eddy simulation (LES) on two static cases. As a consequence, PANS is used to study the effect of an active flow control (AFC) on a dynamic oscillating configuration. The oscillation of the model represents a more realistic ground vehicle flow, where gusts (of different natures) define the unsteadiness of the incoming flow. In the numerical study, the model is forced to oscillate with a yaw angle 10 deg > β > –10 deg and a nondimensional frequency St = fW/Uinf = 0.1. The effect of the periodic motion of the model is compared with the quasi-static flow condition. At a later stage, the dynamic configuration is actuated by means of a synthetic jet boundary condition. Overall, the effect of the actuation is beneficial. The actuation of the AFC decreases drag, stabilizes the flow, and reduces the size of the side recirculation bubble.

Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets

“…The results collected in the previous section are further used as an input to recreate a proof of concept case that shows the effectiveness of streamwise slots at a higher Reynolds number. The model chosen for the experiments was the one used in previous experimental [7] and numerical [8,29] works. Tufts visualizations and PIV, supported by force measurements, are used to evaluate the effectiveness of different control solutions.…”

“…the gap between tractor and trailer, the wheel housing and the under body or the rear side) and all these areas contribute to an aerodynamic drag increase and to the creation of noise and soiling on the side windows [1]. Concerning trucks, a multitude of techniques have been developed during the years, from passive [2,3] to active [4][5][6][7][8] flow control strategies. Specifically, this work focuses on an active flow control (AFC) strategy to suppress the pressure induced flow separation that appears at the vertical front rounded corners of a truck cabin, generally called A-pillars.…”

Upstream actuation for bluff-body wake control driven by a genetically inspired optimization

“…The effect of the actuation has a strong global impact on the flow but it does not strongly affect the height and length of the side recirculation bubble. Previous research (Minelli et al 2016(Minelli et al , 2018, on a similar flow control case, focused (probably too intensively) on the suppression of the side recirculation. Even though drag was effectively reduced, the present strategy shows that a global approach to drag reduction results in a more effective control.…”

“…Considering figure 3(a), there are two main areas that influence the drag value: the side recirculation and the wake. Previous numerical and experimental studies (Minelli et al 2017a,b;Minelli, Krajnović & Basara 2018) showed that the suppression of the side recirculation bubble could significantly reduce the drag on such a bluff body, but it is not clear whether this strategy is optimal to obtain the best global drag reduction and to control the wake dynamics. Only a few recent studies have shown the influence of an upstream control on the wake of a bluff body (Feng & Wang 2014a,b;Qu et al 2019).…”

“…Therefore, two control cases are compared: the side-recirculation-suppression (SRS) case and the GDR case. The former uses a specific frequency indicated by previous literature (Minelli et al 2016(Minelli et al , 2018 to suppress the side bubble, while the latter case is introduced in § 3.2 and obtained from the GA optimization procedure. Figure 18 shows the comparison of the averaged streamwise velocity and flow topology of the three considered cases, while table 4 lists the averaged drag and side force coefficients together with their respective root mean square (r.m.s.)…”