Flow Coefficient Research Articles

The effect of inclination on flow and heat transfer in a 3×3 rod bundle channel in a natural circulation system

Unlike ordinary nuclear power reactors, the floating nuclear power plants are constantly affected by sea waves and are often under inclined condition. The flow and heat transfer characteristics in the rod bundle channel for inclined condition is crucial for the design and operation of floating nuclear power plants. This paper experimentally investigates the flow resistance and heat transfer in an inclined 3 × 3 rod bundle channel at 10∼15 MPa in a natural circulation system and the inclination angle is 10°–30°. The mass flux becomes smaller as the experimental loop is inclined due to the decrease of the natural circulation driving force. As the system inclination angle becomes larger, the mass flux decreases more. Re and the outlet mass quality also affect the mass flux decreasing amplitude for inclined condition. For single phase flow, the friction coefficient correlation in a rod bundle channel is developed and the MAE (mean absolute error) is 2.82 %. The friction coefficients when the channel is inclined are larger than the friction coefficients when the channel is vertical. Correlations for Nu in the static vertical rod bundle channel are also developed and the MAE is less than 2 %. The heat transfer coefficient is enhanced for inclined condition if the effect of mass flux change is eliminated. For flow boiling, inclination has little effect on the number and size of the bubbles for highly subcooled boiling, while inclination has large influence on the flow pattern for saturated boiling. When the inclination angle becomes larger, the two phase multiplier increases. As the outlet mass quality increases, the increasing amplitude of two phase multiplier will become even larger when the inclination angle is larger. The heat transfer coefficient of flow boiling increases when the channel is inclined, and the enhancement is larger when the mass flux is smaller. When the inclination angle is 30°, the boiling heat transfer coefficient could increase by 25.7 % at a low mass flux. The paper reveals the quantitive influence of inclination on both single phase flow and flow boiling in the rod bundle channel. The working pressure and temperature have reached the operating conditions of the floating nuclear power plants, and the results can be applied to the design of nuclear power floating plants and pressurized water reactor using rod bundle fuel assembly.

Wall-scaling prevention in cryogenic external cooler of ammonium chloride solution by liquid-solid fluidization

A double-tube cooler with liquid-solid circulating fluidization operation and corresponding parameter measuring system are developed to avoid fouling of inner walls of heat exchange tubes in a cryogenic temperature external cooler of ammonium chloride solution in soda ash production. Wall-scaling prevention performance of the cooling process is experimentally evaluated using convection and overall coefficients, enhancement factor, wall temperature and fouling resistance. Effects of different volume fractions of added particles, particle size, superficial liquid velocity, and cooling medium temperature on heat transfer are examined. Under present conditions, convection coefficient of liquid-solid flow inside the tube of external cooler is higher than that of the liquid phase flow, increased by 0.7–2.8 times, enhancing cooling performance obviously. Convection coefficient initially increases and then decreases as the volume fraction of added particles increases, reaching its maximum value at a volume fraction of 2.0%. The wall-scaling prevention effect of glass beads mainly depends on the volume fraction of added particles; optimal anti-fouling effects are achieved when adding particles at a volume fraction of 2.0%, regardless of changes in superficial liquid velocity or cooling medium temperature. This study lays a foundation for industrial applications of this new technique of fluidized bed external coolers.

Rated flow coefficient of geometric compensation control valve

Abstract Aiming at the large design error of the rated flow coefficient of existing control valves, it was difficult to meet the requirements of the equipment system. This study adopts the principle of infinite approximation to the existing flow coefficient calculation equation for geometric shape correction compensation, based on which the rated flow coefficient design method was proposed, and simulation and test verification were carried out. The results show that according to the design method, the rated flow coefficient of the control valve can be accurately designed. The variation rule of the simulated value and the test value under the two kinds of spool inner parts is consistent, and the maximum error is not more than 10%, which meets the requirements of industrial standards. The experiment verifies the accuracy and applicability of the design method.

Numerical investigation into rotating instability and the vortex structure near the tip in a transonic compressor rotor

An unsteady simulation with a full-annular computed domain was conducted to explore the flow unsteadiness near the tip region and the mechanism of rotating instability (RI) in the transonic rotor. The numerical static pressure signals were monitored at the tip region. RI was identified by a frequency hump in the spectrum of the static pressure signal in a small mass flow coefficient with a narrow range of 0.9510–0.9174. The cross-power spectrum of two static pressure signals obtained in adjacent passages showed that the circumferential propagation speed of RI decreased with the decrease in the mass flow coefficient. The relative circumferential propagation speed of RI of the prominent mode order was −0.65 to −0.61 times the rotor speed. Details of the flow field near the tip showed that a new vortex structure was induced by the interaction of the tip leakage vortex and the shock wave, which was called as tip secondary vortex (TSV). The TSV was the key parameter to the formation of RI. The impact of the TSV on the pressure side surface generated a low-pressure area and changed the tip load of the adjacent blade. RI is result of the propagation of the interaction between the TSV and the tip load.

Secondary flow characteristics in confluent streams with vegetation

Vegetation commonly exists in river confluences and alters flow structures, affecting the strength and direction of secondary flows. This study investigated the impact of vegetation on the secondary flow structures of a confluence by measuring three-dimensional instantaneous velocities under different vegetative conditions. By utilizing downstream and horizontal flow velocity characteristics, a secondary flow coefficient concept was introduced to describe secondary flow vorticity directions and strengths. The influence of vegetation was assessed in the context of Reynolds stress, the relative strength of secondary flows, and the direction of secondary flow vorticities to clarify the mechanisms by which vegetation affects secondary flows. The findings reveal opposing vertical forces in the confluent section due to incoming tributary flows, resulting in secondary flow generation. Vegetation redistributes cross-sectional water energy, increasing energy convergence within vegetated areas. This amplifies secondary flow strengths and alters vorticity directions. The impact of vegetation on secondary flows is evident in the increase in rotational intensity. Considering various factors, such as the confluence ratio, flow velocity, and distance from the confluence, is crucial, as the influence of vegetation on flows is multifaceted.

Research on Structural Design and Optimisation Analysis of a Downhole Multi-Parameter Real-Time Monitoring System for Intelligent Well Completion

In this paper, based on electro-hydraulic composite intelligent well-completion technology, a new type of downhole multi-parameter real-time monitoring system design scheme is established. Firstly, a multi-parameter real-time monitoring system with a special structure is designed; secondly, its reliability is analysed by applying the method of numerical simulation; finally, in order to verify the reliability of the simulation results, a principle prototype is developed, and indoor experimental tests of fluid flow are carried out. The experimental results show that the flow rate is directly proportional to the differential pressure, and when the flow rate is certain, the higher the water content, the higher the differential pressure. The indoor experimental flow rate of 400~1000 m3/d is measured with high accuracy, and the error range is within 5%. Numerical simulation and experimental results with a high degree of fit, a flow rate of 400–1000 m3/d, the two error range within 10%, the integrated flow coefficient of the experimental value is stable between 0.75–0.815, the simulation value is stable between 0.80–0.86. The mutual verification of the two shows that the flow monitoring design meets the requirements and provides a reference basis for the structural design of the intelligent, well-completion multi-parameter real-time monitoring system.

Aerodynamic and aeroacoustic design of electric ducted fans

This paper describes the aerodynamic and aeroacoustic design of an electric ducted fan (EDF). A prototype EDF was designed and built with three different rotor-stator sets to operate at design flow coefficients ϕd=[0.60,0.75,0.90]. Computational Fluid Dynamics (CFD) simulations show that changing the design flow coefficient changes the proportions of endwall and blade profile loss, with the ϕd=0.75 design providing the optimum balance. CFD predictions of aerodynamic performance are compared with experimental measurements and show good agreement. Data collected from full annulus Unsteady Reynolds-Averaged Navier Stokes (URANS) CFD simulations is used to predict tonal noise radiation using a numerical solution to Farassat's Formulation 1A, and compare favourably to acoustic measurements in an anechoic chamber. All three EDF iterations show similar levels of broadband noise radiation, although tonal noise radiation decreases with increasing design flow coefficient and results in more favourable Sound Quality Metrics performance. Design flow coefficient is shown to have a first-order impact on both the aerodynamic and aeroacoustic behaviour of the EDF, and it is proposed that an optimal design, encompassing both aerodynamic performance and reduced acoustic impact, can be achieved at design flow coefficients between ϕd=0.75 and ϕd=0.90.

Investigation of a Modified Wells Turbine for Wave Energy Extraction

The Oscillating Water Column (OWC) is the most promising self-rectifying device for power generation from ocean waves; over the past decade, its importance has been rekindled. The bidirectional airflow inside the OWC drives the Wells turbine connected to a generator to harness energy. This study evaluated the aerodynamic performance of two hybrid airfoil (NACA0015 and NACA0025) blade designs with variable chord distribution along the span of a Wells turbine. The present work examines the aerodynamic impact of the variable chord turbine and compares it with one with a constant chord. Ideally, Wells rotor blades with variable chords perform better since they have an even axial velocity distribution on their leading edge. The variable chord rotor blade configurations differ from hub to tip with taper ratios (Chord at Tip/Chord at Hub) of 1.58 and 0.63. The computation is performed in ANSYS™ CFX 2023 R2 by solving three-dimensional, steady-state, incompressible Reynolds Averaged Navier–Stokes (RANS) equations coupled with a k-ω Shear Stress Transport (SST) turbulence model in a non-inertial reference frame rotating with the turbine. The accuracy of the numerical results was achieved by performing a grid independence study. A refined mesh showed good agreement with the available experimental and numerical data in terms of efficiency, torque, and pressure drop at different flow coefficients. A variable chord Wells turbine with a taper ratio of 1.58 had a peak efficiency of 59.6%, as opposed to the one with a taper ratio of 0.63, which had a peak efficiency of 58.2%; the constant chord Wells turbine only had a peak efficiency of 58.5%. Furthermore, the variable chord rotor with the higher taper ratio had a larger operating range than others. There are significant improvements in the aerodynamic performance of the modified Wells turbine, compared to the conventional Wells turbine, which makes it suitable for wave energy harvesting. The flow field investigation around the turbine blades was conducted and analyzed.

Influence of Double-Ducted Serpentine Nozzle Configurations on the Interaction Characteristics between the External and Nozzle Flow of Aircraft

To clarify the influence of the serpentine nozzle configurations on the flow characteristics and aerodynamic performance of aircraft, the flow features and aerodynamic performances of the double-ducted serpentine nozzles with different aspect ratios (AR), length–diameter ratios (LDR) and shielding ratios (SR) are numerically investigated. The results show that the asymmetric nozzle flow occurs due to the curved profile of serpentine nozzles, and a local accelerating effect exists at the S-bend, causing the increase in wall shear stress. The unilateral unsymmetrical expansion of the tail jet in the upward direction interacts with the separated external flow of the afterbody, forming an obvious cross-shock wave and shear layer structure. The surface pressure of the afterbody increases along the external flow direction, and decreases sharply in the separation point of the boundary layer. With the increase in AR and LDR, the local accelerating effect of the nozzle flow weakens, while with the increase in SR, the accelerating effect increases. The total pressure recovery coefficient, flow coefficient and axial thrust coefficient all decrease with the increase in AR, LDR, and SR. The thrust vector angle decreases with the increase in AR but is less affected by LDR and SR.

Rheo-optics of giant micelles: SALS patterns of cetyltrimethylammonium tosylate solutions in presence of sodium bromide

In this work, we present a systematic study based on Small-Angle Light Scattering (SALS) patterns of the simple shear flow response of semi-diluted solutions of cetyltrimethylammonium tosylate (CTAT; 5.5 wt.% - 0.12 M) in the presence of sodium bromide (NaBr) at different [NaBr]={0,0.12,0.19,0.25,0.3} M concentrations. We evidence a relationship between rheological and light scattering data that reveals a transition into a fast-breaking regime in the dynamics of wormlike micelles formed by the CTAT/NaBr system (Macías et al., 2011; Fierro et al., 2021). This transition into a micellar fast-breaking regime with salt addition ([NaBr]≥0) appears marked by the following features: (i) a decrease in the relaxation time of the material λ0, accompanied by (ii) a decrease of the viscosity level at low shear rates η0 (Macías et al., 2011; Fierro et al., 2021; Schubert et al., 2003; Alkschbirs et al., 2015; Bandyopadhyay et al., 2003). With these, (iii) the formation of butterfly-like patterns is recorded originating from concentration fluctuations, evolution that is accompanied by: (iv) shear banding in the form of non-monotonic flow curves and (v) slow oscillatory transient responses in start-up flow tests captured theoretically with the Bautista–Manero–Puig (BMP) model. In addition, the Cox–Merz rule is fulfilled at molar salt-to-surfactant ratios of R≥1.5. This results in shorter structure-recovery time-scales than the characteristic-time of the flow (Macías et al., 2011; Fierro et al., 2021; Manero et al., 2002). In the case of the elastic modulus G0, the variation was small, which suggests a transition from an entangled to a multiconnected network, as suggested by Kadoma & van Egmond (1997), Kadoma et al. (1997) and Fierro et al. (2021). From a theoretical perspective, we provide predictions for the shear–stress and the first normal-stress growth coefficients in transient start-up simple shear flow using the BMP model. Here, banding R=1.5 solutions display overshot responses at relatively high shear rates (γ̇=10−30s−1), in-line with experimental findings on the start-up flow of wormlike micellar solutions (Soltero et al., 1999; Lerouge et al., 2004; Hu & Lips 2005; Pipe et al., 2010; Mohammadigoushki et al., 2019). Our results are consistent with those reported in other investigations (Macías et al., 2011; Fierro et al., 2021; Schubert et al., 2003; Alkschbirs et al., 2015; Bandyopadhyay et al., 2003; Kadoma et al., 1997; Soltero et al., 1999; Lerouge et al., 2004; Hu & Lips 2005; López-Barrón et al., 2014) and reveal the influence of the Br−-ion used on the mechanical and optical response of the CTAT-NaBr system.

Calibration of flow differential pressure coefficients on pump-turbine by thermodynamic method

On-line monitoring of flow rate is rather important to evaluate the water consumption of the pump-turbine and the overall efficiency of the pumped storage station. Flow rate can be worked out based on the flow differential pressure measured in the flow passage and coefficients determined on model test. But the coefficients must be calibrated to obtain the reliable flow rate. As thermodynamic method is a common way to measure the discharge of prototype pump-turbine, site test is carried out on a vertical pump-turbine with 600 m rated head to calibrated the coefficients in this paper. Measuring devices are designed to satisfy both the turbine and pump operating conditions, and test results of flow rate at both turbine and pump operating conditions are presented and show that the calibrated coefficients are different to the predicted values. The calibrated results indicate the importance of site calibration on prototype turbine to ensure the monitoring validity on real-time flow rate.

Computational Fluid Dynamics Simulation on Blade Geometry of Novel Axial FlowTurbine for Wave Energy Extraction

Wave energy converters (WECs) utilizing the Oscillating Water Column (OWC) principle have gained prominence for harnessing kinetic energy from ocean waves. This study explores an innovative approach by transforming the pivoting Denniss–Auld turbine blades into a fixed configuration, offering a simplified alternative. The fixed-blade design emulates the maximum pivot points during the OWC’s exhalation and inhalation phases. Traditional Denniss–Auld turbines rely on complex hub systems to enable controllable blade rotation for performance optimization. This research examines the turbine’s efficiency without mechanical actuation. The simulations were conducted using ANSYS™ CFX 2023 R2 to solve the three-dimensional, incompressible, steady-state Reynolds-Averaged Navier–Stokes (RANS) equations, employing the k-ω SST turbulence model to close the system of equations. A grid convergence study was performed, and the numerical results were validated against available experimental and numerical data. An in-depth analysis of the intricate flow field around the turbine blades was also conducted. The modified Denniss–Auld turbine demonstrated a broad operating range, avoiding stalling at high flow coefficients and exhibiting performance characteristics like an impulse turbine. However, the peak efficiency was 12%, significantly lower than that of conventional Denniss–Auld and impulse turbines. Future research should focus on expanding the design space through parametric studies to enhance turbine efficiency and power output.

Implementing fuzzy SMRGT, ANN, and ANFIS for flow coefficient estimation in Antalya River Basin

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.

A hybrid data assimilation method for reconstructing airflow path parameters of a multi-zone model

The indoor airborne pollutant has a great impact on indoor air quality. During the calculation process of pollutant distribution, some difficult-to-obtain parameters are critical in ensuring the calculation accuracy. In this study, we proposed a hybrid data assimilation method combined with Ensemble Kalman Filter (EnKF) and Gibbs sampling to reconstruct airflow path parameters (flow coefficient and flow index) in a multi-zone building model. Specially, we built a scaled multi-zone building model and used CO2 as the tracer gas to simulate the pollutant distribution in the building. The monitored sensor concentration data were used as prior information to reconstruct airflow path parameters of the scaled building model. And the performances of different data assimilation methods were compared. The results show that the EnKF method can reduce the calculation time by 46 % compared to the Gibbs sampling method, but the predicted accuracy decreases by 38 %. However, when we used the hybrid algorithm to reconstruct the airflow path parameters, the calculation time was reduced by 67 % compared to the EnKF method, and the predicted reconstruction accuracy is 7 % higher than the Gibbs sampling method.

Numerical Simulation and Experimental Study of the Rotor–Stator Interaction of a Turbine Under Variable Flow Coefficients

Numerical Simulation and Experimental Study of the Rotor–Stator Interaction of a Turbine Under Variable Flow Coefficients

Relative permeabilities for two-phase flow through wellbore cement fractures

Multiple fluids are likely to exist in fractures and flow paths associated with leaky wellbores, including liquids (e.g., crude oil) and gases (e.g., gas exsolved from liquid). These fluids occupy and move through different portions of the pore spaces within the fractures depending on many factors, including fluid properties, fracture size, and the amount of the different fluids. Upward leakage of any phase, through the fracture, can contaminate water-bearing formations, create hazardous surface conditions, and compromise the functionality of the wellbore. Early signs of wellbore leaks may be expressed by anomalous pressure behavior at surface monitoring points on cavern storage wells. These pressure anomalies are difficult to interpret, necessitating knowledge of the factors that affect the multiphase flow in fractures and porous media. These parameters are critical to modeling multiphase flow in fractures. This insight can guide further diagnosis and maximize leak remediation. Our study focuses on the relationship of the liquid–gas relative permeabilities for representative variable-aperture wellbore cement fracture. To obtain the relative permeability of each phase, two-phase flow tests were conducted where both fluids were flowing simultaneously through a fractured wellbore cement specimen under a range of factors, namely (1) aperture size, (2) capillary numbers, and (3) viscosity ratio. The flow experiments were conducted under a range of confining stresses and flow velocities, using nitrogen gas and silicone oils (of different viscosities) in a specially designed pressure vessel. The sum of gas and oil relative permeabilities were found to be less than one under all conditions, which indicates that the presence of one phase affects the permeability of the other phase, and vice versa. Since the gas phase flow conditions include a significant inertial flow component in addition to viscous flow, the inertial flow coefficients at different saturation states are presented. The factors affecting the relationship between the relative permeabilities are discussed in detail. A new mathematical model for estimating the relative permeability of wellbore cement fracture is presented and experimentally validated.

Barbed arrow-like structure membrane with ultra-high rectification coefficient enables ultra-fast, highly-sensitive lateral-flow assay of cTnI

Acute myocardial infarction (AMI) has become a public health disease threatening public life safety due to its high mortality. The lateral-flow assay (LFA) of a typical cardiac biomarker, troponin I (cTnI), is essential for the timely warnings of AMI. However, it is a challenge to achieve an ultra-fast and highly-sensitive assay for cTnI (hs-cTnI) using current LFA, due to the limited performance of chromatographic membranes. Here, we propose a barbed arrow-like structure membrane (BAS Mem), which enables the unidirectional, fast flow and low-residual of liquid. The liquid is rectified through the forces generated by the sidewalls of the barbed arrow-like grooves. The rectification coefficient of liquid flow on BAS Mem is 14.5 (highest to date). Using BAS Mem to replace the conventional chromatographic membrane, we prepare batches of lateral-flow strips and achieve LFA of cTnI within 240 s, with a limit of detection of 1.97 ng mL−1. The lateral-flow strips exhibit a specificity of 100%, a sensitivity of 93.3% in detecting 25 samples of suspected AMI patients. The lateral-flow strips show great performance in providing reliable results for clinical diagnosis, with the potential to provide early warnings for AMI.

Design, optimization, and performance analysis of a subsonic high-through flow turbine

This paper presents the design method and numerical analysis results of a two-stage high-through flow (HTF) high-pressure turbine. Compared to conventional design principles, the HTF turbine proposed in this study is a kind of high flow coefficient turbine. This design scheme enables the turbine to effectively increase the output power and thrust while maintaining the same windward area. At the design speed, the pressure ratio of the HTF turbine is 3.8, with an adiabatic efficiency of 91.46%. The flow coefficients of the first and second stage are 0.76 and 0.86, respectively, and the loading coefficients are 2.55 and 1.47. Detailed design parameters, flow characteristics, and aerodynamic performance are presented in this paper. Based on the preliminary design result, the second stage turbine was optimized for a wide range of operating conditions. The computational fluid dynamics simulation results show that compared with the traditional turbine, the loading form of the HTF turbine changes from aft-loaded to front-loaded. In addition, there is a certain increase in tip leakage of the turbine. This study achieves high efficiency, while increasing the turbine flow rate, and provides a corresponding reference for the design method of improving turbine flow capacity.

Study on the Influence of Working Characteristics of Centripetal Pump Based on VOF/Mixture Model

Aviation fuel contamination can seriously affect aircraft flight safety, and the centripetal pump is the core component of aviation fuel purification equipment. The performance of centripetal pumps is highly demanded for purification equipment. The operating parameters of centripetal pumps significantly affect the internal flow characteristics, which affects the performance of centripetal pumps. However, the flow characteristics of a centripetal pump influenced by the operating parameters have not yet been elaborated upon. In this research, a three-dimensional numerical simulation of the air-fuel two-phase flow field inside a centripetal pump was carried out using the VOF/Mixture model to investigate the effects of three relatively independent physical quantities, namely, fuel flow, outlet fuel discharge pressure, and rotational speed, on the operating characteristics of the centripetal pump. The flow law inside the flow channel of a centripetal pump was analyzed based on a rotating fluid pressure model, the free liquid surface radius of air-fuel, and the total pressure recovery coefficient. It was found that centripetal pumps have a steady working state and an unsteady working state. In a steady working state, the proportion of separated zones in the flow channel of the centripetal pump is small, the flow coefficient C of the flow channel is greater than 1, and the total pressure recovery coefficient of the centripetal pump is high. In an unsteady working state, the separation zone in the flow channel of the centripetal pump accounts for a large proportion, the flow channel flow coefficient C is less than 1, and the total pressure recovery coefficient of the centripetal pump is low. An unsteady working state can easily occur in small flow, high-speed conditions. By analyzing the working state and flow characteristics of the centripetal pump, the mechanism of the influence of the flow, outlet fuel discharge pressure, and rotational speed on the working state of the centripetal pump is revealed, which provides a basis for the stable operation of the centripetal pump.

Design and aerodynamic characteristics of variable-geometry hypersonic inlet based on shock wave elimination

To solve the problem that the control of shock wave elimination is weakened under off-design conditions, the design concept of a variable-geometry inlet scheme that combines the variable-geometry cowl (translating and diagonalizing) with regulating shock wave elimination is introduced in this paper. The variable-geometry inlet is designed by the theories of oblique shock wave and isentropic wave as well as the Oswatitsch theory. Regulatory law of the variable-geometry cowl based on shock wave elimination is obtained by the geometric relationships between cowl compression angle, cowl shock wave angle, and optimal control point or range. Numerical simulations are conducted to investigate flow field characteristics, control mechanism, and working performance of the inlet. Results reveal that expansion waves have a significant impact on the cowl shock wave and boundary layer interaction, and flow separation. Furthermore, variable-geometry inlet with translating and diagonalizing cowl based on the regulation of shock wave elimination effectively controls and even completely eliminates the flow separation. In terms of inlet performance, the total pressure loss of the variable-geometry inlet decreases such that the total pressure recovery coefficients of the translating cowl and diagonalizing cowl inlets are increased by maximum values of 3.39 % and 9.97 %, respectively. However, the mass flow coefficient of translating cowl inlet decreases, whereas that of the diagonalizing cowl inlet is equivalent to that of the fixed-geometry inlet. The working range can be widened by changing the internal contract ratio of the inlet through translating or diagonalizing the cowl. The results confirm that the scheme of variable geometry inlet with diagonalizing cowl is practicable and reliable and has important guiding significance and value for inlet design.