One of the most commonly used techniques in aerospace engineering is RANS (Reynolds average Navier–Stokes) approach for calculating transonic compressor flow field, where accuracy computation significantly affected by turbulence model used. In this work, we use SA, SST, k-ɛ, and PAFV developed based on side-biased mean fluctuations velocity strain rate tensor to numerically simulate NASA Rotor 67 evaluate modeling numerical calculations compressors. The simulation results demonstrate that...

Aircraft propellers produce relatively large in-plane loads, called propeller 1P during maneuvers such as turning, diving, and lifting, these loads can negatively affect the flight control of aircraft. In order to study change rule aerodynamic in this paper, a mathematical model has been developed based on blade element momentum theory. This was then corrected using Pitt–Peters incoming flow correction method, Prandtl tip root method. Based model, calculation procedure for MATLAB software,...

Abstract To further develop a more effective turbulence model and to improve the calculation accuracy of flow around airfoil, new PAFV has here been constructed by using deformation rate tensor grouping an average fluctuation velocity. evaluate applicability model, numerical calculations airfoil have implemented, which was based on OpenFOAM platform. On basis grid independence research, used calculate low-speed flow-around problem for plano-convex NACA4412 symmetric NACA0012. It also...

A new type of tidal unit-vertical shaft tubular turbine is designed with high efficiency, large flow rate and low water head ,which has power under the 2~3 meters head. According to data being installed units principles turbine’s design, efficiency vertical was discharge head, which suitable for station. The design also considered requirements size details through whole passage were attained. property predicted by 3-d numerical simulation software on passage. Moreover, influences shaft’s...

In order to effectively extract nonstationary and nonlinear fault signature of hydropower units’ signals, a new method, based on Hilbert–Huang transform (HHT), is proposed. This method used carry out EMD (Empirical Mode Decomposition) analysis Hilbert signals firstly then spectrum provide basis for signal feature extraction. The vibration upper brackets in units has been put forward with experimental analysis. results suggest that the can decompose components different frequency domain,...

As a formal modeling and analysis method, colored petri nets (CPN) fits to construct model for software/hardware system with lots of communication parallel/synchronous sharing behavior. Then behavior function performance based on the CPN can be unfolded verify feasibility. The kind new CMP architecture shared multi-channel L2 Cache (AUMCC) is constructed in this article. Processing simulating instruction set deeply penetrated AUMCC model, results well verifies feasibility architecture.

Abuse conditions of torsion and vibration occurred on crankshaft should be eliminated or diminished during the engine design process. 3D model is set up by means simplified system, using concentrated quality method. FEA software was used for analyzing different amplitude orders. Two models with absorber without were compared tested. The results torsional amplitudes-speed so are benefit to new product development eliminating potential mechanical harm.

Motion axes should coordinate exactly in order to get high contouring accuracy. Gain matching is one of the coordinating problems. In this paper, gain effects on accuracy are analyzed for both full-closed and half-closed control loop structures. A simple model proposed reduce error caused by unmatched gains a multi-axis motion system. According model, can be reduced tuning proportional position each axis. Finally, experiments made verify results show that effectively linear circular...

The embedded hobbing CNC is designed,which in the WinCE 5.0 operating system,on hardware platform of ARM+DSP+FPGA ,using Embedded Visual C++(EVC) as a development tool. Hobbing achieves concurrent operation on application order to realizes parallel processing multi-task, such HumanComputer Interaction, data acquisition and issued, analysis, storage so on, based analysis CNCs working principle, using multi-threading technology thread synchronization mechanism possessed by 5.0. simplifies...

A numerical method has been developed to analyze the solid-liquid two-phase flow with coarse particles in vertical pipes. Based on study, a concept of lifting efficiency suggested describe solid by moving liquid. The can be defined as , where v s is average velocity and l speed It was found that when liquid lower than 3m/s, increased increased. On other hand if more will decrease increases. also pipe vibration frequency However remains unchanged compared stationary

New salt core technique for using in the high duty internal combustion engine piston under pressure cast was developed.With special additional ceramic, core’s compressive strength and density performance were improved. Granulation could refine grain microstructure. Orthogonal experiments adopted getting process parameters, this way, oil cooling gallery can be formed completely by new technology. The progress has been widely used pistons.

To change the current phenomenon of “Being an armchair strategist” photoelectric encoder, a virtual absolute encoder is developed using reality techniques. The fundamental theory expatiated, and then development strategy included. Some key technologies their resolutions are presented in development, including formation methods for static coded disc dynamic disc. simulation examples binary code gray showed subsequently. This paper provides worthwhile meaningful assistive tool encoder.

To change the current phenomenon of “being an armchair strategist" in study DC servo system, simulation system that was developed using virtual reality technology. The principle pulse width modulation stated. development strategy software introduced. Some key problems and their solutions were put forward, which includes formation triangular-wave modulation, calculation armature current, assurance duty ratio with average voltage. Finally, example given simulation. This paper provides...

A kind of shared multi-channel on-chip memory CMP architecture is proposed in this article to efficiently support embedded applications. For the being scarce resource, optimal space management mechanism including automatic allocation strategy based on application parallelization mapping pattern and utilization scheme. ILP-model-based analysis system performance verifies that can deeply exploit efficiency improve performance.

In the industrialized cultivation process of fungi, CO 2 concentration control system is a nonlinear, time-delay and time-varying system, which difficult to establish precise mathematical model. Considering situation, prediction model that based on neural network was built, fuzzy controller proposed further Finally, matlab/labview online forecast finished, it verified has higher accuracy with robust character. It also provides new approach key environmental factors under more favorable...