scholarly journals Study on the Fast Extension Mechanism of Double-Cavity Shock Absorber with High-Pressure Piston

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xingbo Fang ◽  
Hu Chen ◽  
Xiaohui Wei ◽  
Hong Nie
Keyword(s):  
High Pressure ◽  
Shock Absorber ◽  
Modeling Method ◽  
Resistance Force ◽  
Cavitation Phenomenon ◽  
Force Modeling ◽  
Extension Mechanism ◽  
Cavitation Effect ◽  
Extension Work ◽  
Calculation Results

Double-cavity shock absorber with high-pressure piston is the core component of the nose landing gear of the carrier-based aircraft, and its fast-extension performance seriously affects the safety of the catapult-assisted takeoff. The design of a carrier-based aircraft in our country is carried out based on the traditional method of fast-extension dynamics, and it is found that the fast-extension capability is larger than designed. This paper analyzes the working principle of the high-pressure piston shock absorber and explains that the high-pressure air cavity pushes the piston rod to extend rapidly, which will cause the cavitation phenomenon in the main oil chamber. Thus, the cavitation in the main oil chamber makes the traditional modeling method of oil-liquid resistance force no longer applicable. Then, the axial force modeling method of shock absorber considering the cavitation effect is proposed. Based on the carrier-based aircraft, the dynamic response of the shock absorber in the process of fast extension is calculated and then it is compared with the calculation results of the traditional dynamic method. It is found that due to the cavitation effect caused by the forced fast extension section of the high-pressure air plug shock absorber, the fast extension work increases by 67.6%, thus, revealing the fast extension mechanism of the double-chamber shock absorber with high-pressure piston and successfully explaining the phenomenon of the fast extension ability exceeding the expectation of the shock absorber.

Topology Optimization Design of High Pressure Storage Tank Structure

2012 ◽  
Vol 430-432 ◽  
pp. 828-833
Author(s):  
Qiu Sheng Ma ◽  
Yi Cai ◽  
Dong Xing Tian
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Topology Optimization ◽  
Storage Tank ◽  
Optimization Design ◽  
Influence Factors ◽  
Element Model ◽  
Design Variables ◽  
Calculation Results ◽  
Pressure Storage

In this paper, based on ANSYS the topology optimization design for high pressure storage tank was studied by the means of the finite element structural analysis and optimization. the finite element model for optimization design was established. The design variables influence factors and rules on the optimization results are summarized. according to the calculation results the optimal design result for tank is determined considering the manufacturing and processing. The calculation results show that the method is effective in optimization design and provide the basis to further design high pressure tank.

The Experimental Investigation of Steam Condensation With Non-Condensable Gas Under Natural Convection

2018 ◽  
Author(s):  
Xizhen Ma ◽  
Wen Fu ◽  
Haijun Jia ◽  
Peiyue Li ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
High Pressure ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Vertical Wall ◽  
Experimental System ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Calculation Results

The non-condensable gas is used to keep the pressure stable in the steam-gas pressurizer. The processes of heat and mass transfer during steam condensation in the presence of non-condensable gas play an important role and the thermal hydraulic characteristics in the pressurizer is particularly complicated due to the non-condensable gas. The effects of non-condensable gas on the process of heat and mass transfer during steam condensation were experimental investigated. A steam condensation experimental system under high pressure and natural convection was built and nitrogen was chosen in the experiments. The steam and nitrogen were considered in thermal equilibrium and shared the same temperature in the vessel under natural convection. In the experiments, the factors, for instance, pressure, mass fraction of nitrogen, subcooling of wall and the distribution of nitrogen in the steam, had been taken into account. The rate of heat transfer of steam condensation on the vertical wall with nitrogen was obtained and the heat transfer coefficients were also calculated. The characteristics curve of heat and mass transfer during steam condensation with non-condensable gas under high pressure were obtained and an empirical correlation was introduced to calculated to heat transfer coefficient of steam condensation with nitrogen which the calculation results showed great agreement with the experimental data.

Detent Force Modeling and Analysis for Vertical Permanent-Magnet Linear Synchronous Motor Using Equivalent Magnetic Network Method

2011 ◽  
Vol 143-144 ◽  
pp. 148-153 ◽  
Author(s):  
Xiao Zhuo Xu ◽  
Xu Dong Wang ◽  
Hai Chao Feng ◽  
Ji Kai Si
Keyword(s):  
Permanent Magnet ◽  
Equivalent Circuit Model ◽  
Synchronous Motor ◽  
Iron Core ◽  
Modeling And Analysis ◽  
Force Modeling ◽  
Detent Force ◽  
Linear Synchronous Motor ◽  
Calculation Results ◽  
Magnetic Network

This paper investigates the detent force modeling of a slotted iron core type vertical permanent magnet linear synchronous motor (PMLSM) for ropeless elevator applications. Variable network non-linear magnetic equivalent circuit model is established to predict the detent force of PMLSM. The topology structure of equivalent magnetic circuit is developed and the permeances are derived and calculated. The end effect of two end teeth is essential for analysis of detent force and it is focused in the modeling. Magnetic saturation of primary iron-core also be taken into account. In final some 3-D finite-element numerical calculation results are used to validate the feasibility of the proposed method.

Upheaval Buckling Analysis of Partially Buried Pipeline Subjected to High Pressure and High Temperature

2011 ◽  
Author(s):  
Jason Sun ◽  
Han Shi ◽  
Paul Jukes
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Soil Cover ◽  
Resistance Force ◽  
Soil Resistance ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Lateral Buckling ◽  
Upheaval Buckling ◽  
Global Buckling

Offshore industry is now pushing into the deepwater and starting to face the much higher energy reservoir with high pressure and high temperature. Besides the significant impacts on the material, strength, and reliability of the wellhead, tree, and manifold valve; high Pressure (HP) also leads to thicker pipe wall that increases manufacturing and installation cost. High Temperature (HT) can have much wider impact on operation since the whole subsea system has to be operated over a greater temperature range between the non-producing situations such as installation, and long term shut down, and the maximum production flow. It is more concerned for fact that thicker wall pipe results in much greater thermal load so to make the pipeline strength and tie-in designs more challenging. Burying sections of a HPHT pipeline can provide the advantages of thermal insulation by using the soil cover to retain the cool-down time. Burial can also help to achieve high confidence anchoring and additional resistance to the pipeline axial expansion and walking. Upheaval buckling is a major concern for the buried pipelines because it can generate a high level of strain when happens. Excessive yielding can cause the pipeline to fail prematurely. Partial burial can have less concern although it may complicate the pipeline global buckling behavior and impose challenges on the design and analysis. This paper presents the studies on the upheaval buckling of partially buried pipelines, typical example of an annulus flooded pipe-in-pipe (PIP) configuration. The full-scale FE models were created to simulate the pipeline thermal expansion / upheaval / lateral buckling responses. The pipe-soil interaction (PSI) elements were utilized to model the relationship between the soil resistance (force) and the pipe displacement for the buried sections. The effects of soil cover height, vertical prop size, and soil resistance on the upheaval and lateral buckling response of a partially buried pipeline were investigated. This paper presents the latest techniques, allows an understanding in the global buckling, upheaval or lateral, of partially buried pipeline under the HPHT, and assists the industry to pursue safer but cost effective design.

scholarly journals A Nonlineark-εTurbulence Model Applicable to High Pressure Gradient and Large Curvature Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Xiyao Gu ◽  
Junlian Yin ◽  
Jintao Liu ◽  
Yulin Wu
Keyword(s):  
High Pressure ◽  
Pressure Gradient ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Wall Region ◽  
Reynolds Stresses ◽  
Wall Functions ◽  
Large Curvature ◽  
Rans Turbulence Models ◽  
Calculation Results

Most of the RANS turbulence models solve the Reynolds stress by linear hypothesis with isotropic model. They can not capture all kinds of vortexes in the turbomachineries. In this paper, an improved nonlineark-εturbulence model is proposed, which is modified from the RNGk-εturbulence model and Wilcox'sk-ωturbulence model. The Reynolds stresses are solved by nonlinear methods. The nonlineark-εturbulence model can calculate the near wall region without the use of wall functions. The improved nonlineark-εturbulence model is used to simulate the flow field in a curved rectangular duct. The results based on the improved nonlineark-εturbulence model agree well with the experimental results. The calculation results prove that the nonlineark-εturbulence model is available for high pressure gradient flows and large curvature flows, and it can be used to capture complex vortexes in a turbomachinery.

Finite Element Analysis of High Pressure Storage Tank

2012 ◽  
Vol 424-425 ◽  
pp. 904-907
Author(s):  
Yi Cai ◽  
Qiu Sheng Ma ◽  
Dong Xing Tian
Keyword(s):  
High Pressure ◽  
Theoretical Basis ◽  
Storage Tank ◽  
Vibration Mode ◽  
Rigid Wall ◽  
Element Analysis ◽  
Calculation Results ◽  
Pressure Storage ◽  
Tank Design ◽  
Theoretical Results

In this paper, based on Ansys the deformation and stress for high pressure long cylindrical natural gas storage tank are analysed. And obtain the stress distribution of the storage tank. The changes of stress are analysed in thickness direction and along the rigid wall. The results and theoretical results are accordance. On this basis, the modal analysis of tank is completed too. Obtained the tank various order natural frequency and vibration mode. The calculation results show that the method is effective and provide the theoretical basis for high pressure tank design

Changes in the Resistance Force of a Magneto-Rheological Shock Absorber Induced by a Magnetic Field

2018 ◽  
Vol 915 ◽  
pp. 39-44
Author(s):  
Tatsuo Sawada ◽  
Takuma Endo ◽  
Yuzo Shimizu ◽  
Hitoshi Nishida
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Shear Flow ◽  
Applied Magnetic Field ◽  
Shock Absorber ◽  
Plug Flow ◽  
Resistance Force ◽  
Mr Fluid ◽  
Bingham Plastic ◽  
Magneto Rheological

In this study, we report the theoretical resistance force of a magneto-rheological (MR) shock absorber. We use the Bingham plastic model to theoretically represent the dynamic behavior of MR fluid flow in a circular pipe under the effect of a magnetic field. Because an MR fluid has yield stresses, the flow is divided into two regions: shear flow and plug flow. We reveal the relation between the resistance force of the MR shock absorber and the applied magnetic field. We conduct experiments and compare the experimental and analytical results to verify the theoretical approach.

Rotordynamic Evaluation of Centrifugal Compressor Using Electromagnetic Exciter

2011 ◽  
Author(s):  
Naohiko Takahashi ◽  
Yohei Magara ◽  
Mitsuhiro Narita ◽  
Haruo Miura
Keyword(s):  
High Pressure ◽  
Frequency Response ◽  
Damping Ratio ◽  
Practical Method ◽  
Magnetic Bearing ◽  
Response Functions ◽  
Mathematical Operation ◽  
Frequency Response Functions ◽  
Calculation Results ◽  
The Stability

Since heavier gases exert larger effects on rotordynamic stability, stability evaluation is important in developing or designing high-pressure compressors. To evaluate the rotor stability during operation, an excitation test using a magnetic bearing is the most practical method. In stability analysis, labyrinth seals can produce significant cross-coupling forces, which particularly reduce the damping ratio of the first forward mode. Therefore, forward modes should be distinguished from backward modes in the excitation test. One method that excites only the forward modes, not the backward modes (and vice versa), is the use of a rotating excitation. In this method, the force is simultaneously applied to two axes to excite the rotor in circular orbits. Two trigonometric functions, i.e., cosine and sine functions, are used to generate this rotation force. Another method is the use of a unidirectional excitation and a mathematical operation to distinguish the forward whirl from the backward whirl. In this method, a directional frequency response function that separates the two modes in the frequency domain is obtained from four frequency response functions by using a complex number expression for the rotor motion. In this study, the latter method was employed to evaluate the rotor stability of a high-pressure compressor. To obtain the frequencies and damping ratios of the eigenvalues, the curve fitting based on system identification methods, such as the prediction error method, was introduced for the derived frequency response functions. Firstly, these methods were applied to a base evaluation under a low-pressure gas operation, in which the stability mainly depends on the bearing property. Using the obtained results, the bearing coefficients were estimated. Next, the same methods were applied to stability evaluations under high-pressure gas operations. The destabilizing forces were also estimated from the test results and compared with the calculation results.

Simulation of Fuel Temperature of Diesel Engine Heating by PTC Materials

2011 ◽  
Vol 480-481 ◽  
pp. 120-125 ◽  
Author(s):  
Xiao Lu Li ◽  
Le Feng Gu ◽  
Cang Su Xu ◽  
Ying Li
Keyword(s):  
High Pressure ◽  
Diesel Engine ◽  
Diesel Fuel ◽  
Heating Temperature ◽  
Rapid Heating ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Fuel Temperature ◽  
Lumped Parameter ◽  
Calculation Results

The PTC materials, as a kind of positive temperature coefficient materials, are used to heat diesel fuel in the high-pressure fuel pipe near the injector in Diesel engine, which have a lot of advantages, such as simple structure, safe and rapid heating, and fixed heating temperature around its Curie point. In order to study its heating effect on diesel fuel of the high pressure fuel pipe, the dynamical models for both the controlled object and PTC heater are presented by the way of lumped parameter, and the heating effects are also simulated and analyzed. The calculation results show that the diesel temperature is heated by the PTC materials effectively. Meanwhile, the heating law by PTC materials heating diesel fuel in the high pressure fuel pipe of engine is also summarized.

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