In this paper, the pressure drop and heat transfer features of a microchannel applying micropin fins are investigated by numerical simulations experiments. The microchannel, which is 20-mm long, 2.7-mm wide, 0.3-mm deep, fabricated with copper consisted staggered diamond fins. visualization experiments, means advanced technology micro-particle image velocimetry (PIV), conducted to discuss mechanism analysing flow regimes. Meanwhile, 3D-coupled applied for combination experiments in research....

With paramount electrical, optical, catalytic, and other physical chemical properties, van der Waals heterostructures (vdWHs) have captured increasing attention. vdWHs are two-dimension (2D) formed via (vdW) force, paving the way for fabricating, understanding, applications of 2D materials. materials large lattice constant difference can be fabricated together, forming a series unique that cannot form earlier. Additionally, provide new platform to study interlayer interactions between...

This study mainly focuses on investigating the influence of meridional contour a steam centrifugal compressor aerodynamic performance. An optimal design method is put forwards, in which hub-line plane modified and optimized. Based data from numerical simulation, characteristics are compared detail among prototype three impellers. It shown that stall margin optimized impeller can be enlarged by approximately 50%, though at point efficiency pressure ratio decreased little bit. Under working...

The unsteady characteristic in the tip region of an axial compressor has been numerically studied with help dynamic mode decomposition analysis. characteristics frequency and modes are compared discussed under different operating points parameters, such as clearance rotating speeds. For flowfield structures region, leakage flow, separation flow shock wave, their relationships unsteadiness detail. Except for caused by interaction between rotor stationary boundaries, it is found that...

The effect of cascade aerodynamic optimization on turbomachinery design is very significant. However, for most traditional methods, parameters are considered as boundary conditions and rarely directly used the variables to realize optimization. Given this problem, paper proposes an improved method in which incidence angle nine geometric parameterize one modified algorithm adopted find with optimal performance. parameterization approach based Non-Uniform Rational B-Splines (NURBS) method,...

This paper studies the influence of tip clearance on flow characteristics related to performance. Based full-passage numerical simulation with experimental validation, several models are established and performance curves obtained. It is found that there exists an optimum for stable working range. By analyzing field in region, role leakage illustrated. In zero-clearance model, separation blockage along suction side main reason rotating stall. As increased value, suppressed by flow. However,...

Abstract The rotating distortion generated by upstream wakes or low speed flow cells is a kind of phenomenon in the inlet middle and rear stages an axial compressor. Highly complex inflow can obviously affect performance stability these stages, needed to be considered during compressor design. In this paper, series unsteady computational fluid dynamics (CFD) simulations conducted based on model 1-1/2 stage investigate effects distorted inflows near casing clearance flow. Detailed analysis...

This paper is concerned with the study of a kind discrete forcing immersed boundary method (IBM) by which loosely aero-elasticity coupled developed to analyze turbine blade vibration. In order reduce spurious oscillations at steep gradients in compressible viscous flowing field, five orders weighted essentially nonoscillatory scheme (WENO) introduced into flow solver based on large eddy simulation (LES). The three-dimensional (3D) full-annulus domain last two stages an industrial steam axial...

For the predicting of compressor noise, Lighthill analogy method based on numerical simulation has usually been adopted. Therefore, accuracy flowing filed is very important to noise estimation. In this paper, nonlinear harmonic (NLH) method, which one promising methods used for prediction, compared with dual time step (DTS) calculating field and a half stage compressor. It found that consumption NLH actually decreased by about 70% DTS. All same, pressure fluctuation in results obtained from...

Abstract In this paper, with the help of partial similarity principle, aerodynamic performance a centrifugal compressor in turbocharger unit is analyzed and improved based on low-speed large-scaled model. order to achieve flow between scaled prototype, tip clearance diffuser outlet diameter have been modified further. It observed from numerical results that relative error prototype less than 0.8%. means field similar though Reynolds number neglected during scaling process. Furthermore,...

Dynamic mode decomposition (DMD) is widely used in extracting the main features of high-dimensional nonlinear systems computational fluid dynamics. However, it cannot be directly applied to real compressors due limitations data acquisition over entire flow field. In order overcome this limitation, our paper proposes a time-delay-locked DMD algorithm. It combines idea phase locking, Hankel time-delay method, and method. Based on it, patterns are successfully extracted unsteady phenomena...

In this paper, a kind of immersed boundary method, the discretized force with ghost cell is introduced to study compressible flow. Meanwhile, an adaptive mesh refinement scheme and wall treatment for turbulent flow are proposed. With help in-house code, accuracy method verified based on several classic tests.

In this paper, a method based on the partial similarity principle is presented to improve aerodynamic design with low cost and high accuracy for 1-1/2 axial compressor. By means of method, during process similar design, machine Mach number flowrate coefficient are maintained. The flow between prototype its large-scaled alternative was observed, according detailed analysis fields rotor stator. As well, relative discrepancies isentropic efficiency pressure ratio two models 1.25% 0.4% at point,...

The compressor flowfield is sensitive to the small geometry in tip region. blade edge, which was usually idealized as “sharp” edge numerical simulation, had been actually filleted during process of machining, coating, and wearing. However, fillet completely neglected performance estimation. Thus, this paper, effect evaluated by establishing several models with edges well sharp a transonic axial compressor. By comparison between it found that can eliminate separation bubble at pressure side...

Rotating stalls are one of the most dangerous phenomena to be avoided in designing and operating axial flow compressors. An understanding evolution characteristics around rotor tip region is important study process stall development. In this paper, some critical stall-related structures, which could not observed by traditional analysis methods, understood using proper orthogonal decomposition (POD) method. The detailed unsteady fields a typical transonic compressor during obtained validated...

Abstract In this paper, due to its advantages of high accuracy and moderate computational cost, detached eddy simulation (DES) is adopted observe detail flow characteristics a kind vertical axial wind turbine equipped with four helical blades. The numerical results obtained from the method have been validated by experiments as well compared those unsteady Reynolds-averaged Navier–Stokes equations (U-RANS). Several critical parameters, such torque, power coefficient, tangential force, are...

In this article, a modified immersed boundary method (IBM) with ghost-cells strategy is introduced to study kind of vertical-axis wind turbine (VAWT). order improve the accuracy numerical calculation and enhance its adaptability, some treatments on IBM for VAWT especially are carried out. The testified by simulation an Eppler387 airfoil. With help method, flowing characteristics have been thoroughly observed understood. Furthermore, effects blade shape, tip vortex secondary performance...

In this paper, the spike-type rotating stall for axial compressor have been studied by dynamic mode decomposition. The full-wheel model with unsteady Navier-Stokes simulation is established and atmospheric boundary condition applied in order to obtain detailed flowfield. Omega-criterion better visualization of vortex. process, including inception stable stall, has captured studied. It found fluctuation flow dominated blade passing stage, while it cell stage. onset triggered increasing...

The distortions, such as total pressure distortion in circumferential and radial directions, generated by low speed flow cell upstream is a common phenomenon at the inlet of an axial compressor. Nonuniform inflow can extremely affect performance stability compressor, needs to be considered during design turbojet engine. In this paper, model proposed provide option simulate flow. And then, series full annulus, unsteady, computational fluid dynamics (CFD) simulations conducted study analyze...

Low-speed model fabrication is an effective testing method for deep understanding flow characteristics with low cost and risk, so it extensively used in design optimization of high speed small scale compressors. Reynolds number, Euler number Strouhal are demanded to retain constant exact similarity method. It nearly impossible practical application. In this paper, improved principle proposed high-to-low scaling process based on the comprehensive considerations geometrical aerodynamic...

The active clearance control system (ACC) of turbine is one the core components,which can reduce fuel consumption civil aero-engine. And tip-clearance change greatly affected by aerodynmaic performance intake grille. To improve performance, in this work, an aerodynamic optimization method grille proposed. This divided into three parts, such as parameterization, fitness evaluation and algorithm. Based on commercial software NX 12.0, parameterized according to seven key geometric parameters....