Double Bellows Research Articles

Новое высокоэффективное двойное сильфонное уплотнение штоков виброперемешивающих устройств

Новое высокоэффективное двойное сильфонное уплотнение штоков виброперемешивающих устройств

Miniature Autoclave and Double Bellows Loading Device for Material Testing in Future Reactor Concept Conditions—Case Supercritical Water

The presented work consists of a test setup study of a new pneumatic material testing device based on double bellows (DBs) loading device and with miniature autoclaves enabling applications at temperature and pressure up to 650 °C and 35 MPa, respectively. It has been demonstrated that it is technically feasible to carry out well defined and controlled material testing in the supercritical water (SCW) environment using this testing system. By using this type of system, it makes possible to investigate the intrinsic role of the applied stress on the deformation behavior of material in light water reactor (LWR) conditions and also in other harsh environments like SCW conditions. In addition, the compactness and versatility of the setup makes this system particularly attractive for deployment in a hot-cell for testing of irradiated materials.

Manufacture and test of seismic bellows for ITER magnet feeder

This paper presents the key manufacturing and testing processes of the prototype ITER feeder seismic bellows. The design of the double bellows was iterated with the results of analysis based on the Expansion Joint Manufacturers Association (EJMA) standard. Each inner and outer bellows was supported in dedicated molds and formed by a hydraulic pressure machine rated at 800tons. The double bellows were constructed by welding individual collars to the end flanges. The seismic bellows was tested with cyclic pressurization of the interlayer space to 2bars absolute pressure for 5 cycles. This was followed by 200 cycles of tensile fatigue test with 90mm of stretching from the nominal design length. After the mechanical fatigue test, a full tensile test with 315mm of stretching from its nominal length was conducted. Helium leak tests, with the sensitivity of the helium leak detector set to 1×10−9Pam3/s of helium, were performed at different stages of pressure and mechanical tests. The prototype bellows was qualified for its leak tightness at all time during the qualification test.

Design of the ITER VUV edge imaging spectrometer and R&D for the rotary motional vacuum feed-through

The ITER vacuum ultraviolet (VUV) spectrometer is aimed at monitoring impurity ion species in plasmas, and it consists of three systems, core survey, edge imaging, and divertor spectrometers depending on positions. In the VUV edge imaging spectrometer, a field mirror and a collimation mirror are used for imaging of the light onto the entrance slit of the VUV imaging spectrometer. To optimize the design of the field mirror box in the ITER port plug, the mirror box mock-up was developed to test installation and alignment. Especially, the mirror alignment using a special tilt stage was tested, and the motional feed-through with a double bellows was developed for the shutter operation. The preliminary qualification test for this rotary motional vacuum feed-through was performed to meet the functional requirement of ITER mechanical feed-through. Leak-tightness for over 15,000 times (larger than operation times) of 360 rotation and backward motion was tested for 1N.m loading condition to the axis rod of the feed-through. In the test, the vacuum inside of the feed-through was monitored, and the feed-through showed good rotation function and leak-tightness during test.

Development of Bellows Design Software using MATLAB

Bellows product is an important part in the area of plant engineering, shipbuilding, and petrochemistry. For safety and durability, it is necessary to consider many factors when designing it. This research developed a U-shaped metal bellows design software based on the EJMA 9th Edition manual. We developed this GUI software using MATLAB software to be able to design four types of bellows: Unreinforced Single Bellows, Unreinforced Double Bellows, Reinforced Single Bellows, and Reinforced Double Bellows. We designed the already proven bellows model to verify this software. We investigated the behavior while changing the thickness of the bellows. As the thickness of the bellows increases, the spring rate, thrust force, and stress increase, and fatigue life decreases. This software will help design engineers save time and effort.

The new build to print design of the ITER Torus Cryopump

The common design of the cryopumps for pumping the divertor and the cryostat has been completed at ITER following more than 10 years of development including prototyping and a number of design studies. This final design, which will be validated by building a Pre-Production Cryopump, achieves a number of simplifications and is expected to solve issues identified in previous concepts.The paper will present the build to print manufacturing design of the cryopump according to European Standards. The fabrication and qualification methods will be discussed and a summary of the main manufacturing methods will be given. The design of the valve assembly and its integration in the cryopump with the valve shaft double bellows will be described in detail.

Thermal-Structural Coupled Analysis of ITER Torus Cryo-Pump Housing

An ITER torus cryo-pump housing (TCPH), which encloses a torus cryo-pump, is connected to a vacuum vessel (VV) by a set of associated double bellows. There are complicated loads due to two different operating states (pumping and regeneration) and foreseeable accidents with the cryo-pump. This paper describes a thermal-structural coupled analysis of the present TCPH according to the allowable stress criteria of RCC-MR, in which the worst cases and outcomes of various load combinations are obtained. Meanwhile, optimization of the structure has been carried out to obtain positive analysis results and an adequate safety margin.

Setup for potential bias experiments on the Saha Institute of Nuclear Physics tokamak

An experimental setup for studying the influence of the radial electric field on very low qa plasma on the Saha Institute of Nuclear Physics tokamak is presented. A high current, high voltage pulsed power supply, using a semiconductor controlled rectifier (SCR) as a dc switch is developed and used to bias a tungsten electrode inserted inside the plasma. The electrode’s exposed length and its position inside the plasma are controlled by a double bellows assembly to optimize the electrode-exposed length. We show that using the force commutation method to turn the SCR off to get the power pulse desired has good potential for carrying out similar kinds of studies, especially in a low budget small tokamak.

TRANSVERSE NATURAL FREQUENCIES AND FLOW-INDUCED VIBRATIONS OF DOUBLE BELLOWS EXPANSION JOINTS

This paper considers the transverse vibrations of fluid-filled double-bellows expansion joints. The bellows are modelled as a Timoshenko beam, and the fluid added mass includes rotary inertia and bellows convolution distortion effects. The natural frequencies are given in terms of a Rayleigh quotient, and both lateral and rocking modes of the pipe connecting the bellows units are considered. The theoretical predictions for the first six modes are compared with experiments in still air and water and the agreement is found to be very good. The flow-induced vibrations of the double bellows are then studied with the bellows downstream of a straight section of pipe and a 90° elbow. Strouhal numbers are computed for each of the flow-excited mode resonances. The bellows natural frequencies are not affected by the flowing fluid but the presence of an immediate upstream elbow substantially reduces the flow velocity required to excite resonance.

FORMULATION AND EXPERIMENTAL VERIFICATION OF A PNEUMATIC FINITE ELEMENT

Many engineering structures completely surround and enclose gas filled volumes. The enclosed gas adds additional stiffness to the surrounding structure. This paper shows how to account for this effect by means of an augmented virtual work principle. The additional term augmenting the virtual work equilibrium statement for the structure is the virtual boundary work done by the pressure of the enclosed gas. The augmented equations are discretized using standard finite element methods, and the additional terms are discussed. The resulting ‘pneumatic’ finite element is shown to be analogous to regular structural finite elements. To assess the accuracy and efficiency and also to illustrate the applicability of the present formulation, a series of four examples was selected. In two of the examples, the behaviour of the end cap of a partially filled plastic food product container is studied. The numerical results using the pneumatic element compare well with an alternative Rayleigh–Ritz solution of the end cap behaviour. The other two examples represent the behaviour of a double bellows air spring shock absorber under static isothermal and dynamic adiabatic conditions. For the static isothermal case, an experimental study was performed with results in good agreement with the pneumatic element solutions. For the dynamic adiabatic loading case, the dynamic stiffness of the air spring was predicted using the pneumatic element. The numerical results agree with experimental data published in an air spring application guide. The examples illustrate that the pneumatic element formulation can be applied to the large deflection analysis of structures that enclose gas filled volumes.

Buckling and rupture of the double bellows expansion joint assembly at Flixborough

The cause of the Flixborough explosion was traced to some temporary pipework. A bypass pipe assembly collapsed, allowing large quantities of volatile cyclohexane to escape. At an early stage in the accident investi­gation, it was realized that this pipework must have failed, but the mechanism by which it had done so was not apparent. A detailed experi­mental and theoretical study had to be carried out to determine what went wrong. The temporary bypass pipe assembly consisted of a dog-leg shaped pipe attached by flexible bellows expansion joints to reactor vessels at each end. It was found that its failure was initiated by a form of structural instability of the bellows called squirming, and that this slightly bent the dog-leg pipe, which then collapsed by jack-knifing at one of its mitre joints. Separate experimental tests showed (i) that the bellows would have remained intact after squirming if the connecting pipe had not jack-knifed, and (ii) that, if the dog-leg pipe had not been bent by squirm­ing, it would not have jack-knifed. It was the combination of bellows and pipe together which proved dangerous, even though each alone was safe. This paper explains the mechanics of squirming and jack-knifing, and describes how a detailed quantitative picture of the original failure was eventually established.

Buckling of Double Bellows Expansion Joints under Internal Pressure

Corrugated bellows expansion joints may buckle under internal pressure in the same way as an elastic strut may buckle under an axial load. This paper is concerned with the analysis of this phenomenon for the ‘universal expansion joint’ which incorporates two bellows joined by a length of rigid pipe. The principal conclusion is that, by providing a correctly designed supporting structure, the critical buckling pressure can be increased to up to four times its value for the same system with no supports.

Afrikanske smede

Afrikanske smede

Avlsten

Avlsten