Abstract: This paper presents a numerical investigation of pressure recovery and flow uniformity in turning diffusers with 90o angle of turn by varying geometric and operating parameters. The geometric and operating parameters considered in this study are area ratio (AR= 1.6, 2.0 and 3.0) and inflow Reynolds number (Rein=23, 2.653E+04, 7.959E+04, 1.592E+05 and 2.123E+05). Three turbulence models, i.e. the standard k-e turbulence model (std k-e), the shear stress transport model (SST-k-W) and the Reynolds stress model (RSM) were assessed in terms of their applicability to simulate the actual cases. The standard k-e turbulence model appeared as the best validated model, with the percentage of deviation to the experimental being the least recorded. Results show that the outlet pressure recovery of a turning diffuser at specified Rein improves approximately 32% by varying the AR from 1.6 to 3.0. Whereas, by varying the Rein from 2.653E+04 to 2.123E+05, the outlet pressure recovery at specified AR turning diffuser improves of approximately 24%. The flow uniformity is considerably distorted with the increase of AR and Rein. Therefore, there should be a compromise between achieving the maximum pressure recovery and the maximum possible flow uniformity. The present work proposes the turning diffuser with AR=1.6 operated at Rein=2.653E+04 as the optimum set of parameters, producing pressure recovery of Cp=0.320 and flow uniformity of su=1.62, with minimal flow separation occurring in the system.
Abstract: This paper presents the experimental and numerical investigation on flowfield of multiple film cooling hole focuses on shallow hole angle at 20°. An in-line hole configuration consist of 20 cooling holes have been considered in the present study. Investigation have been carried out at ReD=6,200 and BR=1.0 with the experimental investigation involves 3D-LDV device to capture the experimental velocity flowfield. The numerical investigation was carried out through RANS analyses with the employment of shear stress transport turbulent model. The results highlights the benefit of shallow hole angle configuration with good agreements have been achieved between the experimental and the numerical results.
Abstract: Tolerance parameters have different effects on robot accuracy. Therefore, it is better to tighten the tolerances of the factors that have statistically significant effect on robot accuracy and widen the tolerances of insignificant ones. By doing so, one not only achieves the given robot accuracy but also reduces manufacturing costs. Objective of this paper is to present an approach used to determine statistical significance of each tolerance parameter of robot manipulator on robot accuracy which can assist robot designers in making decisions regarding tolerance design. In this paper, a comprehensive model of industrial robot manipulator capable of carrying out various applications is developed and computer simulated. Then Taguchi’s Tolerance Design Experiment is applied to determine the statistical significances of the tolerances on robot accuracy. The approach is illustrated by a case study dealing with 6-DOF PUMA 560 robot manipulator.
Abstract: Understanding the evaporation and combustion mechanisms of single droplets of gel propellant is the first stage to predict the burning characteristics in the combustion chamber. This paper, taking into account convection heat for freely falling gelled fuel droplets under normal gravity conditions, as well unsteady mass diffusion and thermal diffusion inside droplet, a theoretical model was developed to understand mass and heat transport mechanisms, and bubble growth within the gel droplet during processes of droplet combustion. The results show that at the first stage, shrinkage of the radius obeys the d2-law; steep temperature gradient and fuel mass concentration gradient appear within droplet, especially region near droplet surface. At the second stage, liquid fuel near the gellant layer within droplet starts to boiling, gellant layer formation resist the vaporizing fuel gas flow to extent; the vapor region appears between gellant layer and vaporizing surface within the droplet, and the droplet expands, swells, the layer thickness decreases until it ruptures.
Abstract: The spacecraft propulsion system is used for geosynchronous orbit transfer, three-axis stabilization and station-keeping. In order to investigate the system dynamics of spacecraft propulsion system with complex pressurization pipelines and propellant supply pipelines, a modular and extensible simulator UPSSim was developed. The pressurant pipelines were separated into several nodes, each node used lumped parameter model; while the propellant feed pipelines used distributed parameter model. Heat transfer between components and environment was also taken into account. The model accurately predicts the transient behavior of the spacecraft propulsion system during start-up and shutdown process, as well as the effect of pipe initial pressure on the priming waterhammer amplitude. The simulation result demonstrates the adequacy of the modular modeling methodology for spacecraft propulsion system dynamic simulation.
Abstract: We present a new technique to the design of high spectral purity numerically controlled oscillator (NCO). In this work, a single look up table (LUT) with sine amplitudes at equally spaced samples was used to approximate the complete sine wave cycle. A simple computation process has been conducted to evaluate the slope coefficients, thus the LUT for mapping those values is eliminated. As a result the NCO structure has been efficiently simplified and the memory reduction has resulted in noticeable logic element (LE) saving. The proposed NCO has been simulated using Xilinx toolbox within the MATLAB Simulink environment. It is shown that the spurious free dynamic range (SFDR) of 96 dBc has been achieved and a compression ratio of 256:1 was attained.
Abstract: In manufacturing and industrial fields used heat exchanger to control of temperature weather as a boiler or cooling system. This system is not stable as the temperature output can easily disturb by noise and other disturbance such as surrounding temperature. To improve the heat exchanger system performance, the mathematical model‘s needed. The heat exchanger mathematical model in this case is constructed using dynamic modelling based on real parameters of the heat exchanger. The simulation result shows almost similar trend of responses with the experiment result, it means they are can used as a model of the heat exchanger.
Abstract: This paper describes how to build routines in Matlab environment for improved ETL process. New architecture real time ETL process stills automated without human – database administrator interference, in cost of reduced accuracy rendered by level of trust. This method is constructed in Matlab environment, due to simple transformation and convert routines and functions. Important is the selection of proper environment for implementation of real time ETL process. Using enhanced architecture of real time ETL process implemented in Matlab make this process stills automated without human – database administrator interference, in cost of reduced accuracy. This method provides a simple transformation and converting routines and functions. First we are describing advantages of Matlab environment followed by real time ETL process description and problem how to achieve real – time in real world. In next part we present our enhanced near real time ETL model with new architecture. And finally we show how to use Matlab routines and toolkit to achieve simplicity in ETL phases of data warehouse needed for simulation and modeling.
Abstract: This paper presents an efficient way for the sterilization of a liquid food (liquid soup) can lying vertically and rotated axially by using a commercial computational fluid dynamics package (ANSYS FLUENT). Aside from the forced convection applied by rotating the can, the simulation involved effect of the natural convection with steam heating to 121°C around all of the can sides. The liquid food in the can was assumed to have constant properties, except for the density (Boussinesq assumption) and viscosity (temperature dependent). By solving the governing equations of mass, momentum and energy, we compared the temperature profile in the thermal sterilization which emphasizes the slowest heating zone (SHZ) of viscous rotation speeds compared to that of a stationary can. The simulation results of temperature profiles with different rotation speeds (5, 10, 15, 20, and 25 rpm) for different periods (1, 19, and 43 minutes) indicated that the combined effect of natural and forced convection causes the higher temperature to reach all of the locations of the SHZ with increased rotational speed. With the higher rotational speed, the heating process time is further reduced when reaching the same lowest temperature at the SHZ of the liquid food can.
Abstract: As new features for driver assistance and active safety system are going rapidly in vehicle, the interface between hardware and simulation model within a virtual and real environment has become necessity. In this paper, a Hardware-in-the-loop Simulations (HILS) test rig has been develop using actual rack and pinion steering mechanism with controller in Matlab xPC Target environment, LVDT and rotary encoder sensors installed for data measurement at various steering angle. It can manipulate the steering mechanism with various control structure, decrease time with real experiment and trial risk as well as improve development efficiency. Results from HILS experimental model demonstrate a linear pattern occurred from maximum lock-to-lock steering wheel angle with acceptable error.