The wettability of shale reservoirs has an important influence on the flow of external fluids. In this paper, the effect of wettability on the self-absorption of hydraulic fracturing fluid under ...different pore size conditions is first analyzed. Then, the mechanism of the influence of wettability pore size on the flow coefficient is elucidated. The results show that (a) as the pore size decreases, the importance of various forces acting on the fluid during the flow process changes, and the solid-liquid interaction will greatly affect the fluid flow in the nanopore. (b) When the radius is 5, the flow enhancement increases from 0.6331 to 0.998 as the radius increases from 0 to 3.141594.(c) The shale inorganic material contains a variety of minerals, and the interaction forces between different mineral surfaces and water molecules are different, resulting in different apparent viscosities.
•The influence of wettability on hydraulic fracturing fluid imbibition is analyzed.•The effect of different pore size conditions is considered.•The wettability pore size influence mechanism of flow coefficient is clarified.
•The flow coefficient of Aksu River Basin in Türkiye is estimated by using SMRGT method.•SMGRT method was applied effectively in hydrological analysis to estimate the flow coefficient.•SMGRT method ...contributes more accurate flood prediction, water resource management and flood mitigation strategies.
The estimation of the flow coefficient is a vital hydrological procedure that holds considerable importance in flood prediction, water resource management, and flood mitigation. The precise estimation of the flow coefficient is imperative in mitigating flood-related damages, administering flood alert mechanisms, and regulating water discharge. It is hard to accurately determine the flow coefficient without a good understanding of the river basin’s hydrology, climate, topography, and soil characteristics. A range of methodologies have been documented in the most recent body of literaturefor flow coefficient modeling. The majority of these methods, however, depend on opaque techniques that lack generalizability. Therefore, this research employed three distinct methodologies—specifically, the Adaptive Neural Fuzzy Inference System (ANFIS), the Simple Membership Function, and the Fuzzy Rules Generation Technique (SMRGT) are all examples of fuzzy inference systems, and Artificial Neural Network (ANN), to achieve its objectives. The Aksu River Basin in Antalya, Turkey, was chosen as the study area. The models underwent multiple permutations of precipitation (P), temperature (T), relative humidity (Rh), wind speed (Ws), land use (LU), and soil properties (Sp) data that were tailored to the particular study region. The study analyzed the results using various performance metrics of the model such as mean absolute error (MAE), Nash–Sutcliffe efficiency coefficient (NSE), root mean square error (RMSE), and correlation coefficient (R2). The results indicate that the SMRGT method resulted in a remarkable degree of accuracy in forecasting the flow coefficient, as demonstrated with the minimal RMSE and MAE values and high correlation coefficient values. The study’s findings suggest that the SMRGT method was applied effectively in hydrological analysis to estimate the flow coefficient, contributing to more accurate flood prediction, water resource management, and flood mitigation strategies.
The filling valve requires high efficiency and stability in the working process, which is closely related to the distribution of the flow characteristics inside the valve. In this study, ...computational fluid dynamics (CFD) methods were present to analyse the pressure, velocity, and other characteristics of the filling valve under different inlet pipe angles and valve openings. The flow characteristics, which are experimentally measured, are consistent with CFD simulation results. Research shows that the increase in the angle of the inlet pipe can improve the uniformity of the flow field inside the valve, produce a better core flow pattern at the valve outlet, and have better fluid stability. Based on the flow characteristics of the valve, to obtain good filling efficiency and stability, a moderate valve opening of 9 mm should be selected, and the flow coefficient can reach 1.08, which is 1.6 times higher than that of 3 mm, and the angle of the inlet pipe should be appropriately increased. This study provides a reference for the use and optimization of filling valves.
•Structural optimization of filling valves.•Improved filling efficiency of filling valves.•CFD simulation improves the smoothness of the filling process of the filling valve.
Marine clay may experience stiffness degradation and catastrophic failure when subjected to complex ocean dynamic loadings. This can result in instability, destruction, or capsizing of offshore ...structures. In this study, marine clay was regarded as a non-Newtonian fluid with shear-thinning behaviour, and the mechanism of progressive stiffness degradation during cyclic loading was discussed from the perspective of fluid dynamics. A series of cyclic direct simple shear tests were conducted on undisturbed marine clay obtained from three offshore sites. Further, the stiffness degradation and flow characteristics under different plasticity index (IP) and cyclic stress ratio (CSR) conditions were investigated and quantified using the stiffness degradation index (δ) and average flow coefficient (κ), respectively. The results revealed that the decrease in δ with the increasing number of cycles (N) in a semi-log scale can be categorised into three modes: (1) "linear" (nonfailure), (2) "fast–linear–fast" (failure), and (3) "linear–stable" (failure). Consequently, a two-parameter model was proposed to predict the δ of failure marine clay from different sea areas with varying IP and CSR values. Moreover, with the increase in N, κ of the nonfailure marine clay increased gradually in a very limited range, thus exhibiting illiquidity characteristics; by contrast, κ of the failure marine clay exhibited a "slow linear–exponential–rapid linear" growth pattern, thus indicating a change in liquidity from weak to strong. Finally, a unified model linking the stiffness degradation and flow characteristics of marine clay under different types and conditions was proposed, where κ at the cyclic failure state (the failure criterion is a double-amplitude shear strain of 15%) was denoted as κf. Evidently, all data points of κ/κf ∼ δ were distributed in a narrow range, and a virtually negative exponential relationship was observed between κ/κf and δ.
•The stiffness degradation of marine clay was investigated based on a shear-thinning non-Newtonian fluid-based method.•A universal equation describing the correlation between δ and N/Nf was presented and validated.•The average flow coefficient was introduced to characterise the fluidity evolving from weak to strong during cyclic loading.•A model for quantifying the stiffness degradation incorporating the normalised average flow coefficient was developed.
Accurate airflow measurement is the key to realize the thermal comfort and energy saving management of VAV air conditioning system, especially for that under low air flowrate conditions. This paper ...proposed a novel damper torque airflow sensor to solve the problem of low range airflow measurement of VAV terminals. The flowrate model is established based on resistance characteristic analysis and the flow coefficient is studied by CFD simulations and experiments. The simulation and experiment results show that there is a good negative linear relationship between the flow coefficient K(θ) and damper opening angle in the range of 10°–50° and the decreasing trend of K(θ) is more intense and nonlinear in the range above 50°. Under the general damper opening range (10°–70°), the quadratic fitting equation of K(θ) can basically meet the error requirements ±5%, but the error is larger as the opening angle exceeds 70°. As the damper opening increases, the airflow rate increases and the torque changes in a very small range under constant static pressure inlet condition, and the proposed airflow sensor has high measurement range ratio of more than 25:1. The study in this paper is helpful to promote the energy saving and building comfort of VAV system.
•A novel damper torque airflow sensor used for VAV terminal is proposed.•Accurate airflow model of the proposed airflow sensor is derived from theoretical analysis.•The flow coefficient is studied by CFD simulations and verified by experiments.•The proposed airflow sensor has high measurement range ratio of more than 25:1.•The proposed airflow sensor can solve the problem of low range airflow measurement and control of VAV terminals.
Labyrinth seals are widely used in centrifugal compressors, turbines, and many other pneumatic systems due to their simplicity of design, reliability, and low cost. The calculation scheme for the ...movement of the working medium in a labyrinth seal is constructed by analogy with the movement of the working medium through holes with a sharp edge. Annular and flat slots, holes, and such a factor as the shaft rotation with a calculated sector of 3 degrees were studied. The purpose of the study is to determine the flow coefficient when the working medium flows through slots of various shapes. To achieve this purpose, modeling of the working medium flow in the FlowVision software was performed. The mass flow and flow coefficients are determined for the studied slot shapes. The convergence of the calculation results was determined by comparing the values of the mass flow rate at the inlet and outlet of the slot. Differences in visualizations of the flow for the studied variants of slots were established. The resulting difference should be taken into account in practical calculations of the working medium mass flow through the slot using a conditional flow rate factor which is determined by the slot design.
This paper investigated the intake flow field of a controllable intake swirl diesel engine using computational fluid dynamics (CFD) methodology. It can be observed that the variation of the intake ...swirl with the opening of the intake baffle shows the two-stage characteristics, while the baffle opening angle of 48° is as a cut-off point. Through the comprehensive analysis of the influence of valve lift and baffle opening angle on flow coefficient, it is concluded that the influence of valve lift on flow coefficient is more sensitive. A mathematical method is used to fit the formula which can calculate the key characteristics of the controllable intake swirl diesel engine. Meanwhile the influence of the swirl ratio on combustion characteristics is investigated. It can be concluded that the swirl ratio has greater influence on the power performance of the diesel engine. When the swirl ratio increases from 0.4 to 1.2, the power performance is increased by 5.79%, and the fuel consumption was also improved. Finally, according to the actual structure of the intake system of diesel engine, a steady-state intake flow test bed was established to verify the accuracy of CFD study of the intake system.
•The swirl ratio of the controllable intake swirl diesel engine has two-stage characteristics.•The diesel engine valve lift is more sensitive to the flow coefficient than the intake baffle.•Two stage characteristics of the intake swirl is the intrinsic property of a diesel engine.•The swirl ratio is more favorable for improving the effective power of a diesel engine.
This paper presents calculation model enabling determination of the leakage rate in labyrinth seals. Described model is based on the Saint-Venant equation. It includes a new type of flow coefficient, ...which was determined based on experimental tests and described depending on the Reynolds number and the radial clearance. The structure of this calculation model can be applied to determine the leakage rate in straight through, staggered labyrinth seals as well as with various number of clearances. This model enables determining distribution of thermodynamic and flow parameters of the gas along the seal length. Results obtained from this model were next compared with experimental data for various types of seals. It enabled determination of kinetic energy carry-over coefficient in geometries under investigation. The value of this coefficient was then compared with the value of the coefficient from the Scharrer's, Neumann's and Hodkinson's models. Obtained results indicate that the value of the kinetic energy carry-over coefficient depends not only on the seal geometry, but also on the pressure decrease.
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•Design a high-pressure test system in a compressible choked flow.•A high-pressure test system was designed.•In the supersonic flow, flow coefficients and local loss factor of valve ...are dependent on several parameters.•Local loss factor has an inverse relationship with the pressure.
In this study, a high-pressure test system was designed to understand the performance characteristics of ball valves in a compressible flow. By measuring the flow parameters, including pressure and temperature at different points in the air circuit, the flow coefficient, and the loss coefficient in the valve are determined in different cases. Determining the flow coefficient variation versus the valve opening condition (by percent) is so effective in controlling the flow. In addition, it will help us to optimize the cross-sectional area of the valve to achieve the desired function. In the supersonic flow, flow coefficients and loss coefficient of the valve are dependent on several parameters, including pressure and fluid flow rate. The basic flow coefficient at different angles indicates that, with decreasing pressure, the base sensitivity of the flow coefficient to the discharge rate decreases, and consequently, it decreases. In addition, by increasing the opening angle of the valve (by increasing the angle from 20° to 80°), the flow coefficient increases (from 0.23 to 49.32). The valve loss coefficient diagrams at a given angle always show a higher sensitivity to the pressure reduction than the discharge rate. This means that the loss coefficient has an inverse relationship with the pressure. Also, with an increase in the valve-opening angle, the amount of loss coefficient decreases, so that it reaches 2 from 10,000 by increasing the angle from 20° to 80°.
In this paper, ANSYS Fluent is used to simulate the three-dimensional flow of the ball valve under different pressure conditions. The flow field torque, speed and pressure distribution are obtained. ...By normalizing the mass flow and torque, a relationship formula between the flow coefficient and torque that varies with the opening degree is constructed. The problem that it is difficult to obtain the flow coefficient and torque coefficient of the ball valve is solved. The results show that the data after the normalization process basically coincide, indicating that the results have a high degree of confidence.
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