Three-dimensional Flow Field Analysis Research Articles

Effect of radial inlet distortion on aerodynamic stability in a high load axial flow compressor

Radial inlet distortion induced by boundary layer separation can significantly affect the aerodynamic performance of the compressor. The effect of radial inlet distortion on the flow structure is numerically investigated in a high load axial flow compressor. The inlet boundary is determined by the experimental results at the downstream of the distortion generator. The results reveal that tip distortion leads to a reduction in the stall margin, whereas hub distortion extends it. Radial distortion redistributes the main flow toward undistorted region due to the obstructive effect of lattice ring. The deficit in axial velocity with tip radial distortion causes the rotor to operate at a higher incidence angle near the casing, while hub radial distortion alleviates the tip blade loading. The detailed three-dimensional flow field analysis indicates that increased blade loading with tip distortion shifts the trajectories of both primary and secondary tip leakage flow toward the leading edge, thereby expanding the blockage region. Conversely, hub radial distortion unloads the rotor tip region, thereby reducing the blockage region induced by tip leakage flow. Additionally, with hub distortion, the location of separation line on the blade suction surface moves closer to the leading edge, and the flow separation around the trailing edge is intensified.

Failure Mechanism and Optimization of Throttle Valve Based on Computational Fluid Dynamics

Throttle valve is an important device in well control manifold. In the process of field use, the valve seat and plug of the valve often have corrosion failure, which brings serious potential safety hazards to the well control work. Using the three-dimensional flow field analysis software of computational fluid dynamics (CFD), it is found that the velocity on the left wall is greater than that on the right. The field failure investigation also proved that the erosion damage mainly occurred on the left wall of the throttle valve, which verified the failure causes of the throttle valve core and valve seat. In addition, the flow field of the erosion resistance device is numerically simulated. The results show that under the given boundary conditions, when the fluid passes through the inlet and outlet of the erosion resistance device, the average velocity changes little. It is known from the velocity curve that under a certain flow rate, the smaller the overflow area is, the greater the velocity is, which is consistent with the hydrodynamic control equation. From the velocity curve data on the alloy head, it is found that the velocity changes little and tends to be horizontal, and the surface velocity of the alloy head is relatively flat, which shows that the fluid velocity on the wall can be effectively reduced after adding the stab prevention short section, so as to reduce the erosion on the wall.

Visual analysis of three-dimensional flow field based on WebVR

Abstract With the rapid development of internet technologies, it is possible to provide computing services and visualize calculated results on the internet. A three-dimensional flow field visualization method based on WebVR is presented in this paper. We devised and built an immersive and interactive three-dimensional virtual reality scene employing web-standard technologies (i.e., HTML5, JavaScript, WebGL, and Ajax) and computing services provided by hydrodynamic software, using GPUs to accelerate the display of flow field in the browser, without the use of plug-ins. On the basis of three-dimensional topography and surface flow field, a three-dimensional flow field presentation method of superimposing multiple sections into the original computational domain was proposed. Furthermore, the description of tracer sphere and path line was adopted to describe the structure characteristics of the flow field. Replacing complete three-dimensional sphere models with textured stylized particles improved the frame rate of the browser greatly when rendering animations. This research enables developers and users of the hydrodynamic model to be immersed in their data of flow field using Google Cardboard. As far as we know, this is the first time that WebVR technology has been applied in three-dimensional hydrodynamic simulation.

Deceleration Performance and Parameter Influence Analysis of the Control Rod Hydraulic Deceleration Device for Control Rod Hydraulic Drive System

Control rod hydraulic drive system (CRHDS), which is invented by INET, Tsinghua University, is a new type of internal control rod drive technology. Control rod hydraulic deceleration device (CRHDD), which consists of the plug, the hydraulic deceleration cylinder, etc., is one of the main components of the CRHDS. The CRHDD performs the rod dropping deceleration function through the interworking of the plug and the deceleration cylinder, which is filled with water, and reduces the rod dropping peak acceleration and the impact force acting upon the control rod to prevent the control rod cruciform blade from being deformed or damaged. The working mechanism of the CRHDD is presented and analyzed. The theoretical model of the control rod dropping process, which is based upon force analysis of the control rod during scram process, three-dimensional flow field analysis, and flow resistance calculation of the hydraulic deceleration cylinder, the kinematics and dynamics analysis of the control rod, is built whose results are compared and validated by the CRHDS scram test results. Then the model is used to analyze the influence of the key parameters, including the fuel case gap, the plug design clearance, the working temperature, etc. on the CRHDD working performance. The research results can give guidance for the design and optimization of the CRHDD.

Flow Dynamics of a Film Cooling Jet Issued From a Round Hole Embedded in Contoured Crater

Recent advances in gas turbine film cooling technology such as round film cooling holes embedded in craters or trenches, and shaped film cooling holes are of interest due to a marked improvement in the effectiveness of film cooling jets. Typically, shaped film cooling holes have higher manufacturing cost, while film cooling holes embedded in craters/trenches etched in thermal barrier coatings (TBC) are seen as a cost-effective alternative. In a recent numerical study Kalghatgi and Acharya (2015, “Improved Film Cooling Effectiveness With a Round Film Cooling Hole Embedded in Contoured Crater,” ASME J. Turbomach., 137(10), p. 101006) reported a novel crater shape to generate anti-counter rotating vortex pair (CRVP) beneath the film cooling jet and showed a significant improvement in film cooling performance. In the present paper, a comprehensive study of flow dynamics is presented to gain insight into the unsteady flow physics of film cooling jet issued from a round hole embedded in the contoured crater. As a baseline case, a round film cooling hole with a 35 deg inclined short delivery tube (l/D = 1.75) is used as from a previous study with freestream Reynolds number based on jet diameter set to ReD = 16,000 and density ratio of coolant to freestream fluid of ρj/ρo = 2.0. These flow conditions are used for the cases of film cooling jet embedded in contoured crater. The results are presented for two crater depths: (i) shallow crater with 0.2D depth and (ii) deep crater with 0.75D depth. First- and second-order flow statistics are presented for all the cases, including the experimental data for baseline case from the literature. Time-averaged and instantaneous flow structures are visualized to reveal the mechanisms of anti-CRVP and attenuating CRVP. The dynamics of flow structures studied using single-point spectral analysis in the shear layer and modal analysis of three-dimensional flow field shows a loss of coherency and increased time scales of shear layer structures as the crater depth is increased, primarily due to attenuating of CRVP in the downstream vicinity of the crater. The modal analysis confirmed reduced magnitude of temperature fluctuations (hot spots) on the cooling wall compared with baseline round film cooling hole. Finally, a 2–5% additional pressure loss due to the crater is reported over the existing ≈7% loss in pressure for baseline case.

J0530303 格子ボルツマン法による半開放形プロペラファンの三次元流動解析([J053-01]流体機械の研究開発におけるEFD/CFD(1),流体工学部門)

J0530303 格子ボルツマン法による半開放形プロペラファンの三次元流動解析([J053-01]流体機械の研究開発におけるEFD/CFD(1),流体工学部門)

Optical Coherence Tomography for the Analysis of Three-dimensional Flow Fields

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Michael Böhmer, Heiko Hinrichs, Klaus D. Hinsch, Jan Kick stein, René Netter, and Christof Surmann, "Optical Coherence Tomography for the Analysis of Three-dimensional Flow Fields," Optics & Photonics News 8(12), 19_1-20 (1997) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Optical Coherence Tomography for the Analysis of Three-dimensional Flow Fields

Optical Coherence Tomography for the Analysis of Three-dimensional Flow Fields

95/05033 Numerical analysis of three-dimensional flow fields with combustion and heat transfer in pulverized coal firing boilers

95/05033 Numerical analysis of three-dimensional flow fields with combustion and heat transfer in pulverized coal firing boilers

Mathematical description of the stimuli to the lateral line system of fish, derived from a three-dimensional flow field analysis. III. The case of an oscillating sphere near the fish

The three-dimensional potential flow field of an oscillating sphere near a fish with an axially symmetric body was investigated mathematically. The spatial distributions of the stimuli to the lateral line system are derived from the flow-field analysis, taking into consideration the hydrodynamical interaction between the fish body and the flow of the oscillating sphere. This was done dependent on the location and the direction of oscillation of the sphere relative to the fish. The theoretical results are compared with measurements of the flow on the surface of a fish model.

Mathematical description of the stimuli to the lateral line system of fish, derived from a three-dimensional flow field analysis. III. The case of an oscillating sphere near the fish

The three-dimensional potential flow field of an oscillating sphere near a fish with an axially symmetric body was investigated mathematically. The spatial distributions of the stimuli to the later...

Advanced pneumatic method for gradient flow analysis

Pneumatic 5-hole probes are widely known reliable sensors for the analysis of three-dimensional flow fields. Since the accuracy of such measurements depends strongly on the volume of the probe and the gradients in the flow, a miniature spherical five-hole-probe with an improved analysis method was developed. With the new method, the complete physically reasonable angle measurement range can be used now by introducing modified calibration functions. A dimensionless examination of the flow around spheres shows the independence of the calibration functions within a wide range of flow velocities. Misrepresentations in flows with high gradients caused by the volume of the probe are estimated by a geometry based correction method. The quality of the method is analysed by an extensive error calculation. Results of measurements in a three-dimensional model combustor are discussed.

Mathematical description of the stimuli to the lateral line system of fish derived from a three-dimensional flow field analysis

Mathematical description of the stimuli to the lateral line system of fish derived from a three-dimensional flow field analysis

Mathematical description of the stimuli to the lateral line system of fish derived from a three-dimensional flow field analysis

Mathematical description of the stimuli to the lateral line system of fish derived from a three-dimensional flow field analysis

遷音速ターボ機械の完全三次元流れ解析 : タイムマーチング法の適用

遷音速ターボ機械の完全三次元流れ解析 : タイムマーチング法の適用