Experimental Study on Structural System of Throttle Multi-Hole Orifices in Refrigeration Plant

2012 ◽  
Vol 479-481 ◽  
pp. 1650-1654
Author(s):  
Tian Yi Zhao ◽  
Ji Li Zhang ◽  
Liang Dong Ma
Keyword(s):  
Structural Design ◽  
Pressure Loss ◽  
Geometric Parameters ◽  
Geometric Features ◽  
Geometric Description ◽  
Structural System ◽  
Refrigeration System ◽  
Pressure Loss Coefficient ◽  
Design And Manufacturing ◽  
Throttle Device

Multi-hole orifices (MOs) is a promising throttle device applying in refrigeration system or plant.The geometric description of multi-hole orifices (MOs) is more complex than single-hole orifices (SOs). The flow control characteristics and structural system of MOs need to be investigated. This paper presents a comprehensive geometric description for MOs by a series of throttle experiments. This paper first defines a comprehensive set of geometric architectures involving orifice arrangement criteria and three geometric parameters, then investigates the effect of various geometric features on the pressure loss characteristics of MOs by throttle tests , finally develops practical models to evaluate the pressure loss coefficient of MOs. The presented structural system of MOs including orifice arrangement criteria, geometric parameters and throttle models, provides convenient conditions for structural design and manufacturing for MOs.

scholarly journals The Application of Machine Learning for Cultivar Discrimination of Sweet Cherry Endocarp

Agriculture ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 6
Author(s):  
Ewa Ropelewska
Keyword(s):  
Sweet Cherry ◽  
Color Space ◽  
Geometric Parameters ◽  
Geometric Features ◽  
Color Spaces ◽  
Discriminative Models ◽  
Sweet Cherries ◽  
Rgb Color Space ◽  
Cultivar Discrimination ◽  
Color Channels

The aim of this study was to evaluate the usefulness of the texture and geometric parameters of endocarp (pit) for distinguishing different cultivars of sweet cherries using image analysis. The textures from images converted to color channels and the geometric parameters of the endocarp (pits) of sweet cherry ‘Kordia’, ‘Lapins’, and ‘Büttner’s Red’ were calculated. For the set combining the selected textures from all color channels, the accuracy reached 100% when comparing ‘Kordia’ vs. ‘Lapins’ and ‘Kordia’ vs. ‘Büttner’s Red’ for all classifiers. The pits of ‘Kordia’ and ‘Lapins’, as well as ‘Kordia’ and ‘Büttner’s Red’ were also 100% correctly discriminated for discriminative models built separately for RGB, Lab and XYZ color spaces, G, L and Y color channels and for models combining selected textural and geometric features. For discrimination ‘Lapins’ and ‘Büttner’s Red’ pits, slightly lower accuracies were determined—up to 93% for models built based on textures selected from all color channels, 91% for the RGB color space, 92% for the Lab and XYZ color spaces, 84% for the G and L color channels, 83% for the Y channel, 94% for geometric features, and 96% for combined textural and geometric features.

Vibration suppression investigation and parametric design of tri-axle straight heavy truck with pitch-resistant hydraulically interconnected suspension

2021 ◽  
pp. 107754632110396
Author(s):  
Fei Ding ◽  
Jie Liu ◽  
Chao Jiang ◽  
Haiping Du ◽  
Jiaxi Zhou ◽  
...  
Keyword(s):  
Surface Area ◽  
Dynamic Load ◽  
Pressure Loss ◽  
Vibration Suppression ◽  
Parametric Design ◽  
Suspension System ◽  
Loss Coefficient ◽  
The Body ◽  
Impedance Matrix ◽  
Pressure Loss Coefficient

The vibration suppression of the proposed pitch-resistant hydraulically interconnected suspension system for the tri-axle straight truck is investigated, and the vibration isolation performances are parametrically designed to achieve smaller body vibration and tire dynamic load using increased pitch stiffness and optimized pressure loss coefficient. For the hydraulic subsystem, the transfer impedance matrix method is applied to derive the impedance matrix. These hydraulic forces are incorporated into the motion equations of mechanical subsystem as external forces according to relationships between boundary flow and mechanical state vectors. In terms of the additional mode stiffness/damping and suspension performance requirements, the cylinder surface area, accumulator pressure, and damper valve’s pressure loss coefficient are comprehensively tuned with parametric design technique and modal analysis method. It is found the isolation capacity is heavily dependent on installation scheme and fluid physical parameters. Especially, the surface area can be designed for the oppositional installation to separately raise pitch stiffness without increasing bounce stiffness. The pressure loss coefficients are tuned with design of experiment approach and evaluated using all conflict indexes with normalized dimensionless evaluation factors. The obtained numerical results indicate that the proposed pitch-resistant hydraulically interconnected suspension system can significantly inhibit both the body and tire vibrations with decreased suspension deformation, and the tire dynamic load distribution among wheel stations is also improved.

Film Cooling and Aerodynamic Performance on Multi-Cavity Squealer Tip of a Turbine Blade

2021 ◽  
Author(s):  
Feng Li ◽  
Zhao Liu ◽  
Zhenping Feng
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Pressure Loss ◽  
Total Pressure ◽  
Aerodynamic Performance ◽  
Total Pressure Loss ◽  
Cooling Performance ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Abstract The blade tip region of the shroud-less high-pressure gas turbine is exposed to an extremely operating condition with combined high temperature and high heat transfer coefficient. It is critical to design new tip structures and apply effective cooling method to protect the blade tip. Multi-cavity squealer tip has the potential to reduce the huge thermal loads and improve the aerodynamic performance of the blade tip region. In this paper, numerical simulations were performed to predict the aerothermal performance of the multi-cavity squealer tip in a heavy-duty gas turbine cascade. Different turbulence models were validated by comparing to the experimental data. It was found that results predicted by the shear-stress transport with the γ-Reθ transition model have the best precision. Then, the film cooling performance, the flow field in the tip gap and the leakage losses were presented with several different multi-cavity squealer tip structures, under various coolant to mainstream mass flow ratios (MFR) from 0.05% to 0.15%. The results show that the ribs in the multi-cavity squealer tip could change the flow structure in the tip gap for that they would block the coolant and the leakage flow. In this study, the case with one-cavity (1C) achieves the best film cooling performance under a lower MFR. However, the cases with multi-cavity (2C, 3C, 4C) show higher film cooling effectiveness under a higher MFR of 0.15%, which are 32.6%%, 34.2%% and 41.0% higher than that of the 1C case. For the aerodynamic performance, the case with single-cavity has the largest total pressure loss coefficient in all MFR studied, whereas the case with two-cavity obtains the smallest total pressure loss coefficient, which is 7.6% lower than that of the 1C case.

The Characteristics Study of Helium-Xenon Mixture in Closed Brayton Cycle for Space Nuclear Reactor Power

2018 ◽  
Author(s):  
Xie Yang ◽  
Lei Shi
Keyword(s):  
Physical Properties ◽  
Pressure Loss ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Loss Coefficient ◽  
Working Fluid ◽  
System Efficiency ◽  
Pressure Loss Coefficient ◽  
Molar Weight ◽  
Xenon Mixture

Differing from the adoption of helium as working fluid of closed Brayton cycle (CBC) for terrestrial high temperature gas cooled reactor (HTGR) power plants, helium-xenon mixture with a proper molar weight was recommended as working fluid for space nuclear reactor power with CBC conversion. It is essential to figure out how the component of helium-xenon mixture affects the net system efficiency, in order to provide reference for the selection of appropriate cycle working fluid. After a discussion of the physical properties of different helium-xenon mixtures, the related physical properties are studied to analyze their affection on the key parameters of CBC, including adiabatic coefficient, recuperator effectiveness and normalized pressure loss coefficient. Then the comprehensive thermodynamics of CBC net system efficiency is studied in detail considering different helium-xenon mixtures. The physical properties study reveals that at 0.7 MPa and 400 K, the adiabatic coefficient of helium-xenon mixture increases with increased molar weight, from 0.400 (pure helium) to 0.414 (pure xenon), while recuperator effectiveness firstly increases and then decreases with the increase of molar weight, and the normalized pressure loss coefficient increases monotonically with molar weight increases. The thermodynamic analysis results show that the adiabatic coefficient has less effect on the net system efficiency, while the net system efficiency increases with increased recuperator effectiveness, and the net system efficiency decreases with normalized pressure loss coefficient increases. Finally, the mixture of helium-8.6% xenon was adopted as working fluid, instead of pure helium, for ensuring less turbine mechanicals (turbine and compressor) stages, and resulting maximum recuperator effectiveness. At the given cold / hot side temperature of 400 / 1300 K, the net system efficiency can reach 29.18% theoretically.

Numerical Investigation and Shape Design Improvement of a Turbine Inlet Combined Valve

2017 ◽  
Author(s):  
Dongting Ye ◽  
Jiaobin Ma ◽  
Yonghui Xie ◽  
Di Zhang ◽  
Sihua Xu
Keyword(s):  
Pressure Loss ◽  
Optimization Theory ◽  
Control Valve ◽  
Good Effect ◽  
Shape Design ◽  
Inlet Valve ◽  
Pressure Loss Coefficient ◽  
Turbine Inlet ◽  
Sst Turbulence Model ◽  
Effective Role

Nowadays, the development of turbines tends to enlarge the capacity and increase the corresponding parameters. Turbine inlet valve is an important part of turbine governing system. Consequently, the high pressure turbine requires good performance of the inlet valve. In this paper, the aerodynamic performance of a real ultra-supercritical power unit turbine inlet combined valve is analyzed in detail via numerical method. At the same time, the shape design of valve plug is improved by means of specific effective methods, including geometrical analysis and quick selection of the angles. A porous medium model is adopted to deal with the strainer structure and it has a good effect on the numerical simulation. The SST turbulence model is finally selected for calculation to obtain reliable results. The results show that the flow in the combined valve presents obvious flow separation nearby the valve plug and downstream of the throat. According to the analysis of pressure and static entropy, it can be concluded that the main pressure loss is concentrated in the strainer and control valve chamber, and an obvious vortex appears in control valve chamber with energy dissipation. Suitable optimization theory plays an effective role in the research. In this process, much attention has been paid to the decrease of pressure loss. Parabola and quick opening shapes are adopted to improve the shape of valve plug and a series of shapes with different angles are tested. The two best optimization models are selected and their results are analyzed. The results show good performance and the pressure loss coefficient reduces from 2.0% to 1.7%.

Rotating Annulus Component Performance Characterisation Based on CFD Analyses

2018 ◽  
Author(s):  
Youming Yuan ◽  
David Hunt
Keyword(s):  
Test Data ◽  
Pressure Loss ◽  
Model Performance ◽  
Internal Flow ◽  
Loss Coefficient ◽  
Performance Data ◽  
Pressure Loss Coefficient ◽  
1D Model ◽  
Torque Coefficient ◽  
Secondary Air

FloMASTER is a 1-D thermo-fluids system simulation tool and its component models depend on the characterisation data of the component performance. Such performance data is mainly based on data banks established from extensive tests exemplified by the books like “Internal Flow” by Miller [1] and “Handbook of Hydraulic Resistance” by Idelchik [2]. One of the key components of the gas turbine secondary air system is the rotating annulus. However, reliable data and correlations for performance characteristics like pressure loss coefficient, torque coefficient, windage and heat transfer for this component are rare and non-existent in the open literature for the case of both walls rotating simultaneously, which is becoming more common in today’s multi-spool military aero engines. To overcome this challenge of lack of reliable performance data and correlations, in this paper the Mentor Graphics 3D CFD tool “FloEFD” is used to model both inner wall rotating and outer wall rotating annulus flow, and to verify the 3D CFD results of performance data in terms of pressure loss coefficient and torque coefficient versus some published test data in the open literature. It is shown that the CFD gives results on pressure loss and torque coefficients that are in good agreement with test data based correlations used in FloMASTER. This demonstrates that 3D CFD can be used as a powerful tool for verifying the existing 1D model, extending the 1D model performance data range and generating new performance data for developing new components where such data is not available from open literature. A future project is to extend this approach to provide performance data for rotating annuli with both walls rotating. Such data will form the basis for developing a new component model for a rotating annulus with both walls rotating.

Optimization of an Axial Turbine Stage for Aerodynamic Inlet Blockage

2011 ◽  
Author(s):  
Mohammad Arabnia ◽  
Vadivel K. Sivashanmugam ◽  
Wahid Ghaly
Keyword(s):  
Pressure Loss ◽  
Suction Side ◽  
Loss Coefficient ◽  
Von Mises Stress ◽  
Optimization Approach ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Design Variables ◽  
Blade Shape ◽  
Von Mises

This paper presents a practical and effective optimization approach to minimize 3D-related flow losses associated with high aerodynamic inlet blockage by re-stacking the turbine rotor blades. This approach is applied to redesign the rotor of a low speed subsonic single-stage turbine that was designed and tested in DLR, Germany. The optimization is performed at the design point and the objective is to minimize the rotor pressure loss coefficient as well as the maximum von Mises stress while keeping the same design point mass flow rate, and keeping or increasing the rotor blade first natural frequency. A Multi-Objective Genetic Algorithm (MOGA) is coupled with a Response Surface Approximation (RSA) of the Artificial Neural Network (ANN) type. A relatively small set of high fidelity 3D flow simulations and structure analysis are obtained using ANSYS Workbench Mechanical. That set is used to train and to test the ANN models. The stacking line is parametrically represented using a quadratic rational Bezier curve (QRBC). The QRBC parameters are directly related to the design variables, namely the rotor lean and sweep angles and the bowing parameters. Moreover, it results in eliminating infeasible shapes and in reducing the number of design variables to a minimum while providing a wide design space for the blade shape. The aero-structural optimization of the E/TU-3 turbine proved successful, the rotor pressure loss coefficient was reduced by 9.8% and the maximum von Mises stress was reduced by 36.7%. This improvement was accomplished with as low as four design variables, and is attributed to the reduction of 3D-related aerodynamic losses and the redistribution of stresses from the hub trailing edge region to the suction side maximum thickness area. The proposed parametrization is a promising one for 3D blade shape optimization involving several disciplines with a relatively small number of design variables.

A Numerical Study of Volute Design in Centrifugal Compressor

2001 ◽  
Author(s):  
Weili Yang ◽  
Peter Grant ◽  
James Hitt
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Loss ◽  
Total Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Numerical Results ◽  
Total Pressure Loss ◽  
Pressure Loss Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Abstract Our principle goal of this study is to develop a CFD based analysis procedure that could be used to analyze the geometric tradeoffs in scroll geometry when space is limited. In the study, a full centrifugal compressor stage at four different operating points from near surge to near choke is analyzed using Computational Fluid Dynamics (CFD) and laboratory measurement. The study concentrates on scroll performance and its interaction with a vaneless diffuser and impeller. The numerical results show good agreement with test data in scroll circumferential pressure distribution at different ΛAR, total pressure loss coefficient, and pressure distortion at the tongue. The CFD analysis also predicts a reasonable choke point of the stage. The numerical results provide overall flow field in the scroll and diffuser at different operating points. From examining the flow fields, one can have a much better understanding of rather complicated flow behavior such as jet-wake mixing, and choke. One can examine total pressure loss in detail to provide crucial direction for scroll design improvement in areas such as volute tongue, volute cross-section geometry and exit conical diffuser.

Geometric Indicators of Flexible Slice Lip

2015 ◽  
Vol 816 ◽  
pp. 188-194
Author(s):  
Krzysztof Talaśka ◽  
Ireneusz Malujda ◽  
Dominik Wilczyński ◽  
Jan Górecki ◽  
Paweł Tarkowski ◽  
...  
Keyword(s):  
Stress State ◽  
Cross Section ◽  
External Factors ◽  
Geometric Parameters ◽  
Geometric Features ◽  
Maximum Deflection ◽  
Paper Making ◽  
Definition Of ◽  
High Flexibility

The paper is thematically connected with paper making machines. This type of the machine is equipped with a head which has a flexible slice lip for skimming the pulp applied to produce the paper. The definition of geometric features of the slice lip is a key issue. The slice lip should be made of material which is resistant to external factors, and designers want to obtain a high flexibility of this element. It is possible to get a high flexibility by forming a proper shape of the slice lip. The paper presents the proposal of dimensionless geometric indicators which combine basic geometric parameters of the slice lip. These indicators are the following: indicator of the cross-section, indicator of the length and indicator of the length of the transverse notch. FEM strength analyses were done – the aim of these analyses was the determination of the stress state and maximum deflection of the slice lip. The authors have analysed the slice lip with holes for mounting the actuators and the slice lip and with transverse notches for increasing its flexibility. The results were presented in the form of graphs.

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