Papers by Keyword: Cavity

Abstract: The compressor contains the oversized cylindrical cavity with two interference output units each in the figure of a circular waveguide H-tee. The H-tees are coupled by a waveguide section and the energy is extracted synchronously through two output ports. The synchronism is provided through using a single microwave switch mutual for both H-tees. Simulation and experimental study of the X-band microwave compressor were carried out. The simulation made it possible to optimize the configuration of the oversized storage cavity and the output element. The amplification factor was 14 dB when the energy was extracted though one output unit at the output pulsewidth of 6...7 ns. Amplification factor and the output power were increased by 2dB and the pulsewidth was decreased down to 3...3.5 ns when the energy was extracted synchronously through two output units.

Abstract: Numerical simulation on removal of contaminated cavity in channel was done for various Richardson number and at three different heated wall inside square cavity. Constrained interpolated profile method (CIP) was used to solve advection part of Navier-Stokes equation while non-advection part was solved by using finite central difference. The contaminant has same properties as the fluid and very small so that the particle can be treated without affected the fluid flow. Simulations shows that heated right wall produced the highest removal process and heated left wall will removed the fewest of contaminant from cavity.

Abstract: In this paper, Constrained Interpolated Profile Method (CIP) was used to simulate contaminants removal from square cavity in channel flow. Predictions were conducted for the range of aspect ratios from 0.25 to 4.0. The inlet parabolic flow with various Reynolds number from 50 to 1000 was used for the whole presentation with the same properties of contaminants and fluid. The obtained results indicated that the percentage of removal increased at high aspect ratio of cavity and higher Reynolds number of flow but it shows more significant changes as increasing aspect ratio rather than increasing Reynolds number. High removal rate was found at the beginning of the removal process.

Abstract: This aim of this research study was to examine the design and construction, as well as to test the performance of hot air-microwave continuous belt dryer machines for drying block rubber STR 20. This industrial type of machine is divided into three major systems: 1) the hot air system, 2) the microwave heating system, and 3) the drying room and conveyor systems. The experiments in this study have shown that the machine can produce heat in the temperature range covered to dry block rubber and the temperature is precise enough within a range of 100 to 130°C (±0.5°C). Security experiments on the microwave leakage have shown that it does not exceed the standards of the HHS (no more than 5 mill watts per square centimeter). Performance experiments have indicated the heat distribution was 83.46 percent which is over 65% of what is considered normal, and the power of the microwave was measured by testing was the value of 24.42 percent of the magnetron wattage used.

Abstract: A hybrid numerical method of combining Large Eddy Simulation (LES) and Lighthill’s acoustic analogy theory is utilized to simulate the flow-induced noise at low Mach numbers. The aerodynamic noise generated by flow through a cavity, which is similar to a valve, is simulated and the results are validated by comparing with the open literature. In the simulation, the turbulent flow is computed with LES. After this, the flow field simulation results are used to compute the flow-induced noise with Lighthill’s acoustic analogy theory based on the commercial software ACTRAN. Finally, the simulation results of the flow-induced noise, including the sound pressure level and the peak frequencies, are analyzed and compared with experimental data. It is validated that the hybrid method of combining LES and Lighthill’s acoustic analogy theory used in this paper is feasible and reliable in engineering applications.

Abstract: The heat transfer property of double skin façade’s façade was analyzed and summarized from the façade’s ventilation pattern, shading mode, cavity width, cavity height, vent openings, the glass optical property and its sequence and convection methods. It showed that the analysis of double skin facade should employ various research methods on the basis of dynamic analysis and comprehensively take multiple factors into consideration on the grounds of actual situation for which may have effects on the heat transfer property of curtains. As a result, more double skin façade with a higher performance of heat transfer can be invented.

Abstract: It was found that evaporation and thermal elastic stress wave and cavity were dominant phenomenon in laser-induced ablation propulsion with liquid propellant according to our perceptual knowledge established in relative experiment and by analysis of physical mechanism of laser-induced ablation of liquid. The research result of the above phenomenon was introduced in this paper in order to give some elicitations to the researchers who were interested in the mechanism of laser propulsion with liquid ablation.

Abstract: A control scheme named the variable-lateral-force cavitator was proposed based on the theory of traditional variable-drag cavitator, the three-dimensional cavitating flow around the cavitator was investigated as well. It is confirmed that the drag, lift, lateral forces and cavity size of underwater vehicle can be effectively adjusted through the movements of control element of variable-lateral-force cavitator in both longitudinal and circumferential directions. In addition, an amount of pitching (or yawing) force equivalent to 30% of drag in magnitude will be produced when the displacement of control element on either side is inconsistent with each other, and the cavity section appears concave inwards simultaneously.

Abstract: In the present study CFD simulation with delayed detached eddy simulation (DDES) are performed to investigate an open cavity at Mach 0.85. Two cavity configurations, clean cavity and cavity with a leading-edge saw tooth spoiler, are modeled. The results obtained from clean cavity prediction are compared with experimental sound pressure level (SPL) data from QinetiQ, UK. Furthermore, comparisons are made with the predicted SPL between the two configurations. The main focuses of this investigation are to obtain a further understanding of the cavity aeroacoustics and test the noise suppression effect by a saw tooth spoiler.

Abstract: Effective complex permittivity measurements of materials are important in microwave engineering and microwave chemistry. This paper describes a convenient laboratory method designed to obtain the permittivity for some materials. The hole for temperature measurement has been designed. The permittivity of materials at deferent temperature can be measured. The measurement results of the real part and imaginary part of the permittivity agree well with literature data at 2.45GHz.