Kriging-assisted design optimization of S-shape supersonic compressor cascades

A kriging based multi objective gray wolf optimization for hydrazine catalyst bed

“…Design of meta-models is based on approximations of the exact analysis that are more efficient in calculation and yield insight into the functional relationship between design parameter (x) and the objective functions (y). The use of Kriging is utilized in this paper which has become popular for metamodeling of time consuming simulations in recent years (Jia & Taflanidis, 2013;Raza & Kim, 2008;Venturelli & Benini, 2016). Kriging meta-model converts the deterministic problem into a statistical framework by combing the global model with a local deviation (Kwon & Choi, 2015).…”

Supersonic Compressor Cascade Shape Optimization under Multiple Inlet Mach Operating Conditions

“…This choice was due to the limited influence of the trailing fraction of the profile on performance, because in typical operating conditions, pressure rise is strongly related to the wave pattern in the fore part of the profile, while the rear fraction is subjected to highly turbulent flow. The work in [2], for example, showed that the difference between full and half camberline parameterization was around 5% in the loss coefficient. In the present work, six control points were employed for the Bézier curve, with the first four having fixed a X-coordinate and a variable Y-coordinate and the fifth having a variable X-coordinate and the ordinate computed according to:…”

“…The imposition of an arbitrary couple (M ∞ , β ∞ ) leads the cascade to operate at different inlet conditions for both variables, on a point belonging to the unique incidence curve. To obtain the desired M 1target , an iterative procedure (inspired by [2] and described in Figure 7) was adopted, in which a low back-pressure was firstly imposed, in order to not influence the inlet flow, along with a tentative initial value for β 1 and the target inlet Mach number M 1target . The β 1sim calculated by the CFD solver was set for the next simulation: it was observed that the β 1sim was always closer to the unique incidence value than the arbitrarily-chosen β 1 .…”

“…This negative slope allowed the shock to remain attached with increased incidence and deviation, incrementing the profile loading without affecting the losses much. The passage oblique shock was more normal in profile with HPR, with higher losses, but also a reduced sensitivity on back-pressure variation [2], allowing for a greater margin before spill point insurgency. Two expansion fans radiated from both the SS and the PS near the leading edge, but with peaks below the baseline values.…”

“…Computational Fluid Dynamics (CFD) in conjunction with automatic methods has been widely used in numerical simulations and optimization of supersonic blades. In [2], a multi-objective optimization of a 2D S-shaped supersonic profile, operating at a unique incidence condition, was conducted using a Kriging-assisted evolutionary algorithm in order to minimize total pressure losses and to maximize the pressure ratio. In [3,4], one-dimensional analytical shock-loss models were developed to predict overall total pressure losses.…”