Simulation Of Fluid-Structure Interaction And Impact Force On A Reed Valve

Air–fuel ratio control of large-bore, two-stroke, natural gas engines, typically used in the oil and gas field, is critically important to maintain stable operation and emission compliance. Many two-stroke applications rely on reed valves to control air and gas induction, which can involve complicated gas flow behavior; standard gas dynamic relationships are typically insufficient to characterize such behavior. Computational fluid dynamic simulations offer the needed complexity, but even so the computational fluid dynamic models, as shown in this work, must also capture the dynamic behavior of the valves themselves. The current work reports on a computational fluid dynamics–based model representing this type of large-bore, two-stroke, natural gas engine using commercially available computational fluid dynamic software. The engine under study is an AJAX E-565 with rated power of 30 kW (40 HP), a bore of 216 mm (8½″), and a stroke of 254 mm (10″). The large engine geometry makes a relatively large solution domain, hence requiring an intense, time-consuming numerical investigation. This large-bore engine works at a rated speed of 525 RPM with a compression ratio of 6 to 1. Two approaches to modeling the reed valve are investigated: (1) a pressure difference–based user-defined function and (2) a fluid–structure interaction user-defined function. The pressure difference–based user-defined function captures reed valve behavior in a simple, binary fashion (i.e. valves are either open or closed based on the pressure difference between the intake pipe and the engine’s stuffing box). The fluid–structure interaction user-defined function, however, predicts the motion of the reed valve strips based on fluid and body motions; although a more complex solution, the fluid–structure interaction user-defined function accurately predicts the engine’s gas exchange process. In this article, the results of each method are presented and validated to show that the added complexity is necessary to properly predict (and thus eventually improve) the engine’s air–fuel ratio control.

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Investigation on Dynamic Characteristics of the Reed Valve in Compressors Based on Fluid-Structure Interaction Method

Applied Sciences ◽

10.3390/app11093946 ◽

2021 ◽

Vol 11 (9) ◽

pp. 3946

Author(s):

Yanfeng Wang ◽

Jin Wang ◽

Zhilong He ◽

Junwei Sun ◽

Tao Wang ◽

...

Keyword(s):

Dynamic Characteristics ◽

Rotational Speed ◽

Fluid Structure Interaction ◽

Three Dimensional ◽

Fluid Structure ◽

Structure Interaction ◽

Pressure Region ◽

Rate Characteristic ◽

Reed Valve ◽

Flow Rate Characteristic

The flow in the gap between the reed and the valve seat has a significant influence on the dynamic characteristics of the reed valve used in reciprocating compressors. The fluid–structure interaction (FSI) method is an effective method for studying reciprocating compressors. A three-dimensional FSI model of a reciprocating compressor with a reed valve is established in this paper, which has an important influence on the flow rate characteristic of reciprocating compressors. Furthermore, an experimental investigation is implemented to verify the FSI model. Based on the established FSI model, the pressure distribution on the reed valve surface is identified by varying the height of the suction valve limiter and the rotational speed of the compressor, which has an important effect on the dynamic characteristics of the reed valve. Although the low-pressure region, due to the Bernoulli effect on the surface of the reed, hinders the rapid opening of the valve to some extent, it is obviously beneficial to the timely closure of the valve and increases the volumetric efficiency of the compressor. Moreover, the optimal height of the valve limiter and the appropriate rotational speed of the compressor are obtained.

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Experimental and Numerical Studies on Fluid–Structure Interaction for Underwater Drop of a Stone-Breaking Crusher

Journal of Marine Science and Engineering ◽

10.3390/jmse10010030 ◽

2021 ◽

Vol 10 (1) ◽

pp. 30

Author(s):

Jung Min Sohn ◽

Ji Woo Kim ◽

Sang Ho Kim

Keyword(s):

Impact Force ◽

Numerical Study ◽

Fluid Structure Interaction ◽

Experimental Results ◽

Arbitrary Lagrangian Eulerian ◽

Angular Rotation ◽

Fluid Structure ◽

Structure Interaction ◽

Free Falling ◽

The Impact

There are many methods for crushing seabed rock such as a using a free-falling crusher, blasting, and chemical liquid expansion. Blasting and chemical liquid expansion can lead to environmental destruction, noise pollution, and civil complaints. Therefore, a free-falling crusher is generally recommended for use. Understanding the characteristics of a crusher in water and the impact force on the ground is helpful for designing a crusher and dredge work. In this study, drop tests of 50 and 70 ton crusher models that were scaled down by 15 times were investigated. The tests were conducted in a water basin by the Research Institute of Medium and Small Shipbuilding (RIMS) in Korea. Four water depths were considered with different falling locations: water surface and air. Moreover, a numerical study on Fluid–Structure Interaction (FSI) analysis for a free-falling crusher was conducted by applying the Arbitrary Lagrangian–Eulerian (ALE) element and the Grüneisen Equation of State (EoS) to fluid models. The crusher and ground were modeled as Lagrangian elements to estimate the impact force on the ground. Before comparing the crusher model, a free-falling sphere model was used to develop FSI technologies by comparing past Computational Fluid Dynamics (CFD) and experimental results. Moreover, the recommended mesh size and fluid domain for FSI analysis are provided to achieve good results via convergence tests. Comparison between experimental and numerical methods demonstrated a similar tendency such that impact force increased at a higher depth. Certain numerical results agree with average values of experimental results; however, multiple numerical cases exhibit a moderate difference. This is because of angular rotation between the crusher and ground when the crusher hits the ground during experiments.

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The Sliding and Overturning Analysis of Spent Fuel Storage Rack Based on Dynamic Analysis Model

Science and Technology of Nuclear Installations ◽

10.1155/2016/8368504 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Yu Liu ◽

Daogang Lu ◽

Yuanpeng Wang ◽

Hongda Liu

Keyword(s):

Impact Force ◽

Fluid Structure Interaction ◽

Seismic Loading ◽

Spent Fuel ◽

Analysis Model ◽

Fem Model ◽

Fluid Structure ◽

Structure Interaction ◽

Fuel Storage ◽

Interaction Experiment

Spent fuel rack is the key equipment for the storage of spent fuel after refueling. In order to investigate the performance of the spent fuel rack under the earthquake, the phenomena including sliding, collision, and overturning of the spent fuel rack were studied. An FEM model of spent fuel rack is built to simulate the transient response under seismic loading regarding fluid-structure interaction by ANSYS. Based on D’Alambert’s principle, the equilibriums of force and momentum were established to obtain the critical sliding and overturning accelerations. Then 5 characteristic transient loadings which were designed based on the critical sliding and overturning accelerations were applied to the rack FEM model. Finally, the transient displacement and impact force response of rack with different gap sizes and the supporting leg friction coefficients were analyzed. The result proves the FEM model is applicable for seismic response of spent fuel rack. This paper can guide the design of the future’s fluid-structure interaction experiment for spent fuel rack.

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