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Showing papers on "Chamber pressure published in 2016"


Journal ArticleDOI
Paul Segall1
TL;DR: In this paper, an approximate solution for spherical magma chambers surrounded by Maxwell viscoelastic shells (radius R1) in elastic half-spaces following a sudden decrease in pressure is analyzed.
Abstract: I analyze an approximate solution for spherical magma chambers (radius R1) surrounded by Maxwell viscoelastic shells (radius R2) in elastic half-spaces following a sudden decrease in pressure. Mass flux into the chamber is proportional to the pressure difference between a deep source and chamber, P∞−p(t). Solutions depend on R2/R1, ≡βc/(βm+βc), where βm,βc are magma and chamber compressibilities, the relaxation time tR, and the recharge time for the elastic system, τ. Without recharge the system exhibits either post-eruptive deflation or, for incompressible magmas, partial reinflation. More generally immediate post eruptive inflation is favored by large ,tR/τ and small R2/R1. With short tR and large the time for magma chamber pressure to recover increases significantly. Post-eruptive creep increases the chamber pressure, decreasing the pressure gradient driving recharge, delaying pressure recovery. Following eruption the hoop stresses, which are initially compressive, relax toward the radial stress causing them to go through a local (relative tension) maximum. The magma pressure in excess of the dike normal compression at the chamber wall, can recover to pre-eruptive values well before the chamber pressure or erupted mass recovers. This suggests that dikes could nucleate at the chamber margin well before sufficient pressure has recovered to drive them far from the chamber. For some parameters co-eruptive deflation has not fully recovered when the magma overpressure relative to hoop stress in the elastic region is restored to pre-eruptive values, a condition assumed to be sufficient for eruption.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the contribution of near-wall chemical reactions to heat flux is investigated and quantified by suitable numerical analyses, and a parametric analysis is carried out varying chamber pressure, wall temperature, and propellant combination.
Abstract: Cooling of liquid rocket thrust chamber walls to allowable solid material temperatures induces near-wall chemical reactions, which are known to have an important role on the heat transfer from the hot gas to the wall. In this study, the contribution of near-wall chemical reactions to heat flux is investigated and quantified by suitable numerical analyses. Numerical results are first compared to literature experimental data of wall heat flux in subscale calorimetric thrust chambers for both oxygen/methane and oxygen/hydrogen propellant combination. Then, a parametric analysis is carried out varying chamber pressure, wall temperature, and propellant combination. This study highlights that oxygen/methane combustion products are more subject to near-wall recombination phenomena. They provide an increase of wall heat flux between 20 and 30% with respect to the frozen flow model evaluation, whereas in the case of oxygen/hydrogen, the wall heat flux increase due to recombination reactions is between 7 and 14%.

37 citations


Journal ArticleDOI
TL;DR: In this article, the potential of flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves was investigated, and a dynamic model was developed to analyze the pumping dynamics of the pump and validated by experimental results.
Abstract: This paper investigates the potential of flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves. A dynamic model is developed to analyze the pumping dynamics of the pump and validated by experimental results. The effects of cross-angle on the flow ripples in the outlet and inlet ports, and the piston chamber pressure are investigated. The effects of pressure relief grooves on the optimal solutions obtained by a multi-objective optimization method are identified. A sensitivity analysis is performed to investigate the sensitivity of cross-angle to different working conditions. The results reveal that the flow ripples from the optimal solutions are smaller using the cross-angle and pressure relief grooves than those using the cross-angle and ordinary precompression and decompression angles and the cross-angle can be smaller. In addition, when the optimal design is used, the outlet flow ripples sensitivity can be reduced significantly.

35 citations


Journal ArticleDOI
TL;DR: In this paper, results from experimental studies of a two-dimensional subscale chamber that can nearly replicate full-scale acoustic modes are described, which are primarily driven by injector elements at the endwalls of the rectangular chamber.
Abstract: High-frequency combustion instabilities result from a coupling between modes of heat release and chamber acoustics. Because the geometric dimensions of the chamber define the relevant acoustic modes, it is particularly difficult to study transverse instabilities in anything other than a full-scale chamber. In this paper, results from experimental studies of a two-dimensional subscale chamber that can nearly replicate full-scale acoustic modes are described. The acoustic modes are primarily driven by injector elements at the endwalls of the rectangular chamber. They were designed to be unstable, based on a vortex-shedding mechanism postulated on earlier results from longitudinal studies. The 27-cm-wide by 19-cm-long chamber produced transverse instabilities with a first width-mode frequency of about 2000 Hz, with no longitudinal mode content in the pressure signal. The chamber comprises a linear array of seven gas-centered swirl coaxial liquid injectors, designed to flow either bipropellants, only oxidizer...

26 citations


Patent
07 Jan 2016
TL;DR: In this article, a method for operating a substrate processing chamber includes after performing a process using a fluorine-based gas in the substrate chamber: a) during a first predetermined period, supplying a gas mixture to the substrate process chamber including one or more gases selected from a group consisting of molecular oxygen, molecular nitrogen, nitric oxide and nitrous oxide and supplying RF power to strike plasma.
Abstract: A method for operating a substrate processing chamber includes after performing a process using a fluorine-based gas in the substrate processing chamber: a) during a first predetermined period, supplying a gas mixture to the substrate processing chamber including one or more gases selected from a group consisting of molecular oxygen, molecular nitrogen, nitric oxide and nitrous oxide and supplying RF power to strike plasma in the substrate processing chamber; b) during a second predetermined period after the first predetermined period, supplying molecular hydrogen gas and RF power to the substrate processing chamber; c) repeating a) and b) one or more times; d) purging the substrate processing chamber with molecular nitrogen gas; e) increasing chamber pressure; f) evacuating the substrate processing chamber; and g) repeating d), e) and f) one or more times.

26 citations


Journal ArticleDOI
TL;DR: In this paper, a computational analysis of transverse acoustic instability for an experimental combustion chamber with rectangular cross section is presented, where the governing equations are solved on multiple coupled grids, which allow for a fast simulation, even in a serial run.
Abstract: A computational analysis of transverse acoustic instability is presented for an experimental combustion chamber with rectangular cross section. The analysis is shown to be efficient and accurate. The governing equations are solved on multiple, coupled grids, which are two-dimensional in the combustion chamber and nozzle and one-dimensional in the injector port. Thus, they allow for a fast simulation, even in a serial run. Because of the lengthscale difference, the jet flame behavior at the injectors (including effects of turbulence) can be decoupled from the acoustic effects and solved on a local grid for each jet flame emerging from an injector. Wave propagation through the injector feed ports is evaluated on additional, one-dimensional grids for each injector port. The overall algorithm is used to simulate the Purdue seven-injector rocket engine; good quantitative agreement between simulations and experiment is achieved. All simulations that are predicted to be unconditionally unstable are confirmed by ...

26 citations


Journal ArticleDOI
TL;DR: In this paper, a large-eddy simulation is performed to simulate high-frequency combustion instability in a single-element atmospheric combustor, and the coupling mechanism between the flame and acoustic mode is explored based on the largeeddy simulation results.
Abstract: Large-eddy simulation is performed to simulate high-frequency combustion instability in a single-element atmospheric combustor. Simulations are conducted for corresponding combustion-instability experiments, and the self-excited combustion instability is successfully captured. The first tangential mode of the combustion chamber is excited in the large-eddy simulation, and the amplitude and frequency of the pressure fluctuations are consistent with the experimental observations. The first tangential mode in the large-eddy simulation was observed at 1 kHz, and the peak-to-peak amplitude was approximately 4% of time-averaged pressure. The higher-order modes were also observed in the large-eddy simulation at frequencies ranging from 2 to 4 kHz, although those amplitudes were approximately one-fourth of the first tangential mode. The coupling mechanism between the flame and acoustic mode is explored based on the large-eddy-simulation results. The periodic ignition of the unburnt H2/O2 mixture exhibits lifted c...

24 citations


Journal ArticleDOI
TL;DR: In this paper, an experimental investigation was conducted to analyze hot-surface ignition of n-hexane-air mixtures, where a glow plug was used to initiate ignition in a flammable mixture.

22 citations


Journal ArticleDOI
Jionghui Liu1, Rong Xue1, Liang Chen1, Xiufang Liu1, Yu Hou1 
TL;DR: In this article, a closed loop R134-a spray cooling system was designed using a commercial full-cone nozzle to generate the spray for the cooling of an upward plain copper surface.

21 citations


Journal ArticleDOI
TL;DR: In this article, transparent conducting Cu-doped NiO thin films were deposited on quartz glass substrates by radio frequency magnetron spattering and a relatively high transmittance of 73% was achieved.
Abstract: Transparent conducting Cu-doped NiO thin films were deposited on quartz glass substrates by radio frequency magnetron spattering. The fabricated thin films were all in amorphous phase. A relatively high transmittance of 73% was achieved. The density ratio of Ni3+/(Ni2+ + Ni3+) ions in the films decreased with increasing O2 gas pressure in the fabrication chamber, which caused a decrease in the carrier concentration of the films. The increasing pressure also led to the increase in Hall mobility. By controlling the chamber pressure and substrate temperature, p-type transparent conducting NiO films with reasonable electrical properties were obtained.

20 citations


Journal ArticleDOI
01 Jan 2016-Vacuum
TL;DR: In this article, a computational fluid dynamics model to optimize atomic layer deposition (ALD) process is presented, in which the temperature, precursor mass fraction, mass flow and pressure have been quantitatively analyzed by combining surface chemical reactions with species transport.

Journal ArticleDOI
TL;DR: In this paper, a parametric study based on an unsteady mathematical model of a pyrotechnically actuated device was performed for design optimization, and the design optimization was conducted by employing a GA.
Abstract: A parametric study based on an unsteady mathematical model of a pyrotechnically actuated device was performed for design optimization. The model simulates time histories for the chamber pressure, temperature, mass transfer and pin motion. It is validated through a comparison with experimentally measured pressure and pin displacement. Parametric analyses were conducted to observe the detailed effects of the design parameters using a validated performance analysis code. The detailed effects of the design variables on the performance were evaluated using the one-at-a-time (OAT) method, while the scatter plot method was used to evaluate relative sensitivity. Finally, the design optimization was conducted by employing a genetic algorithm (GA). Six major design parameters for the GA were chosen based on the results of the sensitivity analysis. A fitness function was suggested, which included the following targets: minimum explosive mass for the uniform ignition (small deviation), light casing weight, short operational time, allowable pyrotechnic shock force and finally the designated pin kinetic energy. The propellant mass and cross-sectional area were the first and the second most sensitive parameters, which significantly affected the pin’s kinetic energy. Even though the peak chamber pressure decreased, the pin kinetic energy maintained its designated value because the widened pin cross-sectional area induced enough force at low pressure.

Journal ArticleDOI
TL;DR: In this article, the ruthenium thin films were grown by atomic layer deposition (ALD) using a sequential supply of dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C16H22O6Ru) and H2 as a reactant at a substrate temperature of 250 °C.
Abstract: The ruthenium (Ru) thin films were grown by atomic layer deposition (ALD) using a sequential supply of dicarbonyl-bis(5-methyl-2,4-hexanediketonato) Ru(II) (C16H22O6Ru) and H2 as a reactant at a substrate temperature of 250 °C. Deposition was possible using H2 molecules without a plasma by increasing the chamber pressure to above 10 Torr. Specifically, high-quality Ru films with a low resistivity of ∼40 μΩ cm and few amount of oxygen (∼1.2 at. %) were obtained under a chamber pressure of 300 Torr though the oxygen was contained in the precursor. Under the optimized conditions, self-limited film growth with regard to the precursor and reactant pulsing times was confirmed under elevated chamber pressures. The ALD-Ru process proposed in this study showed one of the highest growth rates of 0.12 nm/cycle on a thermally grown SiO2 substrate, as well as a very low number of incubation cycles (approximately 12 cycles). Cross-sectional view transmission electron microscopy showed that no interfacial oxide had form...

Journal ArticleDOI
TL;DR: In this paper, an experimental study has been carried out to investigate the nature of transients in vacuum ejector flows during start-up and the dynamics in flow characteristics, and the results show that the secondary stream induction progresses with non-uniform rates with the ramping primary jet pressure during startup.
Abstract: An experimental study has been carried out to investigate the nature of transients in vacuum ejector flows during start-up and the dynamics in flow characteristics. The results show that the secondary stream induction progresses with non-uniform rates with the ramping primary jet pressure during start-up. The initial evacuation period is subjected to gradual and highly perturbed secondary fluid entrainment. In this phase, the secondary stream induction by the shear layer is asymmetric leading to an un-even vacuum generation in the secondary chamber. In the second phase, the secondary pressure fluctuations are found to be ceased for a critical primary jet pressure followed by a rapid induction of the secondary fluid till the primary jet expands to the diffuser wall. The transition from the first phase to the second phase is caused by the secondary stream flow choking in the diffuser. Following the second phase, a stable stage exists in the third phase in which the vacuum pressure decreases only marginally. Any further attempt to increase the secondary chamber vacuum level beyond the third phase, by increasing the primary jet total pressure, results in flow reversal into the secondary chamber, spoiling the already achieved vacuum level. In the fourth phase of start-up, a complicated shock interaction transformation from a Mach reflection (MR) to regular reflection (RR) occurs within the diffuser. It is also observed that the primary jet pressures for the minimum secondary chamber pressure, the minimum secondary pressure, and the primary pressure for MR-RR transformation decrease initially with increase in diffuser length and then increase. It is found that the decreasing and increasing trends are caused by the pressure recovery and Fanno effects, respectively.

11 Jul 2016
TL;DR: In this article, the authors used SCORGTM to generate a conformal boundary mapping (CMBM) model of a twin screw compressor with a rotor configuration of 4/5 and a main rotor diameter of 127 mm.
Abstract: Modelling of screw compressors using Computational Fluid Dynamics (CFD) offers better insight into the working chamber of twin screw machines when compared with chamber models. As shown by authors in earlier publications, CFD models predict performance of dry gas and refrigeration compressors fairly accurately. However numerical flow models used for modelling of oil flooded twin screw compressors are still at the development stage. This is mainly due to the lack of understanding of the flow complexity and the techniques used for solving coupled equations that represent interactions between the gas and the oil in such machines. This paper presents the modelling approach used for calculation of the performance of an oil flooded screw compressor. It requires a structured numerical mesh which can represent all moving parts of the compressor in a single numerical domain. Such mesh is generated by SCORGTM using novel boundary distribution technique called casing-to-rotor conformal boundary mapping. A test oil injected twin screw compressor with rotor configuration 4/5 and 127 mm main rotor diameter was measured in the compressor rig of the Centre for Compressor Technology at City University London. Measurements of the chamber pressure history and integral parameters of the compressor such as mass flow rate of gas and oil, indicated power and temperatures are used for the comparison with CFD results. The analysis showed a close match in the prediction of the mass flow rates of gas. The indicated power obtained by CFD predictions matched well with the measured shaft power. The model provided an exceptional visualization of the interaction of gas and oil inside the compression chamber. The mixing of the phases, distribution of oil, heat transfer between gas and oil and also effects on sealing due to high oil concentration in leakage gaps were well captured.

Journal ArticleDOI
TL;DR: The results show that the proposed PI-PD method has a better performance in the set-point tracking and disturbances rejection than those comparative methods.

11 Jul 2016
TL;DR: In this article, an indicator diagram of a twin-shaft screw-type expander prototype SE 51.2 is presented and analyzed in detail, and the impact of the injected water on the expander's delivery rate and mechanical efficiency is presented.
Abstract: Twin-shaft screw-type expanders offer a high potential for energy conversion in the lower and medium power range, for instance as expansion engines in Rankine cycles for exhaust heat recovery. With regard to minimizing internal leakages and lubricating moving machine parts, an auxiliary liquid or liquid working fluid, for example in organic Rankine cycles (ORC)1, can be fed to the screw expander. In this paper, indicator diagrams of a twin-shaft screw-type expander prototype SE 51.2 designed at the Chair of Fluidics at TU Dortmund University are presented and analyzed in detail. The experimental investigations are carried out on a hot-air test rig with an expander inlet manifold water injection. The time-dependent working chamber pressure is recorded by means of high-resolution absolute pressure transmitters. Hereby, specific aspects of working chamber pressure measurements are mentioned. Based on the indicator diagrams, relevant influence mechanisms on the expander's operational behavior resulting from water injection are determined. Additionally, the impact of the injected water on the expander’s delivery rate and mechanical efficiency is presented.

Journal ArticleDOI
TL;DR: In this paper, nitrogen-doped ZnO-NPs were synthesized using an arc-discharge-mediated gas-evaporation method that was recently developed.
Abstract: Both n-channel and p-channel thin-film transistors have been realized on ZnO nanoparticle (NP) layers sprayed onto quartz substrates. In this study, nitrogen-doped ZnO-NPs were synthesized using an arc-discharge-mediated gas-evaporation method that was recently developed. Sprayed NP layers were characterized by scanning electron microscopy and Hall effect measurements. It was confirmed that p-type behaving NP layers can be obtained using ZnO-NPs synthesized with lower chamber pressure, whereas n-type conductivity can be obtained with higher chamber pressure. pn-junction diodes were also tested, resulting in clear rectifying characteristics. The possibility of particle-process-based ZnO-NP electronics was confirmed.

Journal ArticleDOI
Jianyu Yuan1, Yanxiang Li1, Ningzhen Wang1, Ying Cheng1, Xiang Chen1 
TL;DR: In this article, the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter (Do = 0.25 mm, Pc =0.4 MPa), and the bubble generation mechanism is proposed based on the Rayleigh-Plesset equation.
Abstract: The bubble generation process in conditioned A356 alloy melt through submerged spiry orifices with a wide diameter range (from 0.07 to 1.0 mm) is investigated in order to prepare aluminum foams with fine pores. The gas flow rate and chamber pressure relationship for each orifice is first determined when blowing gas in atmospheric environment. The effects of chamber pressure (Pc) and orifice diameter (Do) on bubble size are then analyzed separately when blowing gas in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on bubble size based on the experimental data. It is found that the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter (Do = 0.25 mm, Pc = 0.4 MPa). The bubble generation mechanism is proposed based on the Rayleigh–Plesset equation. It is found that the bubbles will not be generated until a threshold pressure difference is reached. The threshold pressure difference is dependent on the orifice diameter, which determines the time span of pre-formation stage and bubble growth stage.

Journal ArticleDOI
03 Nov 2016
TL;DR: In this article, the formation of aluminum-doped zinc oxide (ZnO:Al) films on glass substrates in an RF-sputtering chamber modified to facilitate in situ heating during deposition is reported.
Abstract: RF sputtered, aluminum-doped zinc oxide (ZnO:Al or AZO) is an attractive candidate material as transparent conductive oxides in the fabrication of opto-electronic devices. High electrical conductivity and optical transparency are two key requirements in such applications. This paper reports on the formation of AZO films on glass substrates in an RF-sputtering chamber modified to facilitate in situ heating during deposition. The influence of chamber pressure, RF power, and deposition temperature has been systematically studied and the electrical parameters such as film resistivity, carrier concentration, carrier mobility as well as optical transmission have been analyzed. Film deposition at 250 °C and a low chamber pressure of 0.5 mT resulted in a very low resistivity of 2.94 × 10−4 ohm cm. The structural properties of the films with the lowest resistivity have been further analyzed by x-ray diffraction (XRD) and PL measurements and are compared with the film deposited at room temperature. The XRD results show dominant peaks along (103) orientation for the AZO films with slightly improved crystal quality at higher temperature. Evolution of near band edge and deep level emission photoluminescence peaks also indicate improvement in crystal structure with increased deposition temperature.

Journal ArticleDOI
TL;DR: In this article, the authors studied the ignition-transient process in the end-burning-grain solid rocket motor and developed simplified numerical models for a mass-added ignitor, a grain-propellant combustion, 3) the opening of the nozzle closure, and 4) the enhancement of heat transfer on the surface of the solid propellant.
Abstract: The ignition-transient process in the end-burning-grain solid rocket motor has been studied. Simplified numerical models for 1) a mass-added ignitor, 2) a grain-propellant combustion, 3) the opening of nozzle closure, and 4) the enhancement of heat transfer on the surface of the solid propellant have been developed. The individual influence of the input of ignitors (energy strength and input time), the physical and chemical properties of propellants (critical burning temperature, burning rate, thermal conductivity, and initial temperature), and the breaking pressure of closure on the ignition transient have been systemically compared. The three stages of the ignition-transient process, namely, ignition induction, flame spreading, and chamber charging, have been successfully reproduced. The interior ballistics agrees with the ground-experimental data. The rapid generation of the initial flame and the creation of the “second peak” of the chamber pressure both contribute to a successful ignition. The results...

Journal ArticleDOI
TL;DR: In this paper, the effect of the technological parameters on the rate of the plasmochemical etching of single-crystal quartz was evaluated. But the experimental results made it possible to evaluate for the first time the influence exerted by the technological parameter on the etching rate, and it was shown that the influence decreased in the following order: pressure in the reaction chamber, bias potential, RF power, and hydrogen flow rate.
Abstract: Main technological parameters of the process of local plasmochemical etching of single-crystal quartz were optimized. The etching was performed in a gas mixture of CF4 and H2 under radio frequency (RF, 13.56 MHz) discharge excitation. The scientific experiment design by the Taguchi matrix method was used to examine the effect of chamber pressure, RF generator power, negative bias applied to the substrate holder, and hydrogen flow rate on the rate of the etching process. The experimental results made it possible to evaluate for the first time the influence exerted by the technological parameters on the etching rate. It was shown that the influence exerted by the technological parameters in the conditions under study decreases in the following order: pressure in the reaction chamber, bias potential, RF power, hydrogen flow rate.

Journal ArticleDOI
TL;DR: In this article, the growth of powder formation in Argon (Ar) diluted Silane (SiH4) plasma using 27.12 MHz assisted plasma enhanced chemical vapor deposition process with the approach of plasma diagnosis was reported.
Abstract: We report the growth of powder formation in Argon (Ar) diluted Silane (SiH4) plasma using 27.12 MHz assisted Plasma Enhanced Chemical Vapor Deposition process with the approach of plasma diagnosis. The appearance of powder during processing contaminates the process chamber which further can alter the film properties; hence plasma diagnosis was vital towards detecting this variation. This work presents for the first time a diagnosis of powder in the plasma using Impedance Analyser (V/I probe) at various concentrations of Argon dilution (10%–90%), chamber pressure (0.3 Torr–0.6 Torr), and applied power (4 W–20 W). Efforts were made to understand the different phases of powder formation (i.e., chain and accumulation process, coalescence phase and α → γ′ transition (powder zone)) by monitoring and evaluating the plasma characteristics such as discharge voltage and current (Vrms and Irms), Impedance (Z), phase angle (ϕ), electron density (ne), bulk field (Eb), and sheath width (ds). From the results of plasma ...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the influence of plasma etching for fused silica glass to find the best tradeoff between etch rate and profile of TGVs, including bias power, gas flow rate, ratio of etching gases and reaction chamber pressure using inductively coupled plasmas.
Abstract: Through glass via (TGV) technology is considered to be a cost effective enabler for the integration of micro electromechanical systems and radio frequency devices. Inductively coupled plasma and Bosch etching process comprise one of the most pervasive methods for through silicon via (TSV) formation. Unfortunately an equivalent process for glass etching remains elusive. In this paper, the influence of plasma etching for fused silica glass were investigated to find the best tradeoff between etch rate and profile of TGVs. The process parameters including bias power, gas flow rate, ratio of etching gases and reaction chamber pressure using Ar/C4F8 inductively coupled plasmas were studied. The etching results show that all these three parameters have a significant impact on the etch rate. Furthermore, the adjustment including total flow rate and ratio of Ar/C4F8 and chamber pressure can be used to control the via profile. Constant fused silica glass etch rate greater than 1 μm/min was obtained when chiller temperature was 40 °C with etching time of 60 min. The profile angle of TGVs with nearly 90° was also achieved.

Patent
23 Mar 2016
TL;DR: In this paper, a liquid closed-type static-pressure rotary table experiment apparatus of changeable restrictors is described, where each restrictor is sealed through a sealing ring and fixed through four long bolts.
Abstract: The invention discloses a liquid closed-type static-pressure rotary table experiment apparatus of changeable restrictors. According to an oil pad position, the restrictors are arranged on an outer side of a rotary table of a corresponding position respectively. Each restrictor is sealed through a sealing ring and is fixed through four long bolts. The number of each kind of the restrictors is eight. The different restrictors are changed and dynamic and static tests are performed on the restrictors respectively. An eddy current displacement sensor, a pressure sensor and a temperature sensor are used to measure oil chamber pressure, an oil film thickness and an oil chamber temperature respectively. An acceleration sensor is used to test a vibration mode of a rotary table working bench. A flowmeter arranged at a rotary table oil inlet is used to measure an oil liquid inlet flow. A pressure gauge on a fuel tank is used to measure oil supply pressure of a static-pressure rotary table. By using the experiment apparatus, convenience is provided for researching influences of the different restrictors on static-pressure rotary table bearing performance; material cost is saved and guarantees are provided for solving a problem in engineering, optimizing a structure parameter of the rotary table and increasing workpiece processing precision.

Journal ArticleDOI
TL;DR: In this article, trenches with various sidewall slant angles were generated on 4H silicon carbide substrate using Cl2/O2-based reactive ion etching, and a method combining photoresist and hydrofluoric acid clean was proposed to eliminate the micromasking effect while keeping the sidewall passivation.
Abstract: In this article, trenches with various sidewall slant angles were generated on 4H silicon carbide substrate using Cl2/O2-based reactive ion etching. A series of experiments was conducted to investigate the effects of chamber environmental conditions, including Cl2/O2 mixing ratios, radio frequency power, and process pressure. The results indicate that the chamber pressure, ion energy, redeposition of etch products/byproducts, and even the existence of photoresist are critical factors affecting the slant angle. The introduction of oxygen not only changes the etch profile but may also cause a serious problem known as the micromasking effect. A method combining photoresist and hydrofluoric acid clean was proposed to eliminate the micromasking effect while keeping the sidewall passivation.

Journal ArticleDOI
TL;DR: In this article, the effects of chevrons on the performance of a supersonic vacuum ejector-diffuser system are investigated numerically and evaluated theoretically in a three-dimensional geometrical domain.
Abstract: The effects of chevrons on the performance of a supersonic vacuum ejector-diffuser system are investigated numerically and evaluated theoretically in this work. A three-dimensional geometrical domain is numerically solved using a fully implicit finite volume scheme based on the unsteady Reynolds stress model. A one-dimensional mathematical model provides a useful tool to reveal the steady flow physics inside the vacuum ejector-diffuser system. The effects of the chevron nozzle on the generation of recirculation regions and Reynolds stress behaviors are studied and compared with those of a conventional convergent nozzle. The present performance parameters obtained from the simulated results and the mathematical results are validated with existing experimental data and show good agreement. Primary results show that the duration of the transient period and the secondary chamber pressure at a dynamic equilibrium state depend strongly on the primary jet conditions, such as inlet pressure and primary nozzle shape. Complicated oscillatory flow, generated by the unsteady movement of recirculation, finally settles into a dynamic equilibrium state. As a vortex generator, the chevron demonstrated its strong entrainment capacity to accelerate the starting transient flows to a certain extent and reduce the dynamic equilibrium pressure of the secondary chamber significantly.

Patent
13 Jan 2016
TL;DR: In this article, a positive pressure air supply system and a control method for a building with a fire control signal is described. But the system is in communication connection with a building or other control systems, and detection and control are convenient.
Abstract: The invention discloses a positive pressure air supply system and a control method The system comprises a positive pressure air supplying machine, an intelligent control unit and n air supply units of the same structure The method comprises the steps that the elevator front chamber pressure and the staircase pressure are set through the intelligent control unit; during pressurization air supply, the air pressure of a staircase is larger than the air pressure of the elevator front chamber, and the air pressure of the elevator front chamber is larger than the air pressure of an aisle; when a fire control signal exists, a positive pressure air supply machine is controlled to work, the difference value between a detection pressure numerical value of a staircase pressure sensor and the barometric pressure is obtained through the intelligent control unit, and the maximum value of the difference value is taken as a reference signal to be compared with the staircase pressure set value, so that the opening degree of an electric bypass pressure-relief valve is adjusted to enable the actually-detected staircase pressure value to approach to the set value; and when the fire control signal is eliminated, the intelligent control unit controls the positive pressure air supplying machine to stop working The system is in communication connection with a building or other control systems, and detection and control are convenient

Patent
Abhishek Dube1, Xuebin Li1, Yi-Chiau Huang1, Hua Chung1, Schubert S. Chu1 
05 Apr 2016
TL;DR: In this paper, the authors present a method for forming a doped silicon epitaxial layer on semiconductor devices at increased pressure and reduced temperature, which is referred to as DIPT.
Abstract: Embodiments of the present disclosure generally relate to methods for forming a doped silicon epitaxial layer on semiconductor devices at increased pressure and reduced temperature. In one embodiment, the method includes heating a substrate disposed within a processing chamber to a temperature of about 550 degrees Celsius to about 800 degrees Celsius, introducing into the processing chamber a silicon source comprising trichlorosilane (TCS), a phosphorus source, and a gas comprising a halogen, and depositing a silicon containing epitaxial layer comprising phosphorus on the substrate, the silicon containing epitaxial layer having a phosphorus concentration of about 1×10 21 atoms per cubic centimeter or greater, wherein the silicon containing epitaxial layer is deposited at a chamber pressure of about 150 Torr or greater.

Journal ArticleDOI
14 Nov 2016-Energies
TL;DR: In this article, the authors evaluated the flash-atomization behavior of a water-LCO2 mixture with regard to the spray angle and penetration length during a throttling process.
Abstract: Liquid carbon dioxide-assisted (LCO2-assisted) atomization can be used in coal-water slurry gasification plants to prevent the agglomeration of coal particles. It is essential to understand the atomization behavior of the water-LCO2 mixture leaving the injector nozzle under various conditions, including the CO2 blending ratio, injection pressure, and chamber pressure. In this study, the flash-atomization behavior of a water-LCO2 mixture was evaluated with regard to the spray angle and penetration length during a throttling process. The injector nozzle was mounted downstream of a high-pressure spray-visualization system. Based on the results, the optimal condition for the effective transport of coal particles was proposed.