Journal articles: 'Subsonic diffuser'

1

Ribi, Beat, and Peter Dalbert. "One-Dimensional Performance Prediction of Subsonic Vaned Diffusers." Journal of Turbomachinery 122, no. 3 (February 1, 1999): 494–504. http://dx.doi.org/10.1115/1.1303816.

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A simple one-dimensional theory to predict the performance of a diffuser using as few empirical factors as possible is presented. The prediction method uses two empirical functions to assess both the pressure recovery and the losses. The functions have been calibrated from experimental data from the company’s standard diffusers. The method is, however, adaptable for any type of subsonic vaned diffusers, provided that the empirical functions can be calibrated from measurements. The pressure rise in the diffuser is calculated from the continuity equation, taking into account the blockage, while the losses are determined by means of displacement and momentum thickness. These values are calculated at design point from an integral boundary layer calculation. To take into account the influence of flow separation at off-design, the calculated displacement and momentum thickness are increased according to empirical functions. When designing a new impeller, the method provides a simple way to evaluate the diffuser, resulting in the best combination in terms of efficiency and range. It further provides a simple means of estimating the change to be expected in a known stage performance characteristic due to a modification of the diffuser geometry.[S0889-504X(00)01703-7]

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2

Li, Qingkuo, Zhigang Sun, Xingen Lu, Yingjie Zhang, and Ge Han. "Investigation of New Design Principles for the Centrifugal Compressor Vaned Diffusers." International Journal of Aerospace Engineering 2022 (February 25, 2022): 1–16. http://dx.doi.org/10.1155/2022/4480676.

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Diffuser’s aerodynamic performance is crucial for the centrifugal compressors, while at present the universal principles for the optimization design of the vaned diffusers are still not available. In this paper, three vaned diffusers with different inlet Mach numbers were numerically studied in order to explore new design principles for the centrifugal compressor vaned diffusers. It proved that there are practical and effective design principles for the vaned diffuser optimizations, the performance of the vaned diffuser can be improved by carefully control of two aerodynamic parameter distributions: Tangential velocity (Vt) and Meridional velocity (Vm). The vaned diffusers with subsonic, transonic and supersonic inlet conditions were optimized with the new design principles, and the peak efficiencies were increased by 4.23%, 2.15% and 2.59%, respectively. The stage pressure ratios were increased by 3.36%, 1.39% and 6.49%, respectively, and their surge margins were also improved substantially. Finally, since the Vt and Vm could affect each other during the optimization process, an interactive optimization design procedure was also presented in this paper in order to accelerate the optimization process.

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3

Johnston, J. P. "Review: Diffuser Design and Performance Analysis by a Unified Integral Method." Journal of Fluids Engineering 120, no. 1 (March 1, 1998): 6–18. http://dx.doi.org/10.1115/1.2819663.

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A computational tool, called a Unified Integral Method (UIM) is reviewed. The method is used for preliminary design and performance analysis of simple diffusers with thin inlet boundary layers and subsonic flow in their inviscid core regions. The assumptions needed for application of a UIM are not very restrictive in many practical cases: straight diffusers with thin, turbulent inlet boundary layers and subsonic, irrotational core flows. The method provides designers with useful results including pressure recovery, location of separation and stalled regions, and exit plane profiles which may be used to evaluate total pressure loss and various flow distortion indices. Besides reviewing some basic concepts concerning stall and separation, describing the basis of the method and some details for making the UIM work, actual cases where it was tested versus data are discussed. In addition, UIM results are compared to results obtained by a RANS method run in a well known duct flow solver for a subsonic diffuser where data are also available. In another case, its output and data were compared to results from a CFD code typical of the many design codes in use in industry today. In both cases, the UIM results were as good, or better than those from the higher level methods, and the UIM is much simpler and easier to use as a design tool.

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4

Zhang, Wei-Li, Doyle D. Knight, and Don Smith. "Automated Design of a Three-Dimensional Subsonic Diffuser." Journal of Propulsion and Power 16, no. 6 (November 2000): 1132–40. http://dx.doi.org/10.2514/2.5688.

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5

Reichert, B. A., and B. J. Wendt. "Improving curved subsonic diffuser performance with vortex generators." AIAA Journal 34, no. 1 (January 1996): 65–72. http://dx.doi.org/10.2514/3.13022.

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6

Ibaraki, Seiichi, Tetsuya Matsuo, and Takao Yokoyama. "Investigation of Unsteady Flow Field in a Vaned Diffuser of a Transonic Centrifugal Compressor." Journal of Turbomachinery 129, no. 4 (August 11, 2006): 686–93. http://dx.doi.org/10.1115/1.2720505.

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Transonic centrifugal compressors are used with high-load turbochargers and turboshaft engines. These compressors usually have a vaned diffuser to increase the efficiency and the pressure ratio. To improve the performance of such a centrifugal compressor, it is required to optimize not only the impeller but also the diffuser. However the flow field of the diffuser is quite complex and unsteady because of the impeller located upstream. Although some research on vaned diffusers has been published, the diffuser flow is strongly dependent on the particular impeller exit flow, and some of the flow physics remain to be elucidated. In the research reported here, detailed flow measurements within a vaned diffuser were conducted using a particle image velocimetery (PIV). The vaned diffuser was designed with high subsonic inlet conditions marked by an inlet Mach number of 0.95 for the transonic compressor. As a result, a complex three-dimensional flow with distortion between the shroud and the hub was observed. Also, unsteady flow accompanying the inflow of the impeller wake was confirmed. Steady computational flow analysis was performed and compared with the experimental results.

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7

Jo, Seonghwi, Sanghyeon Han, Hong Jip Kim, and Kyung Jin Yim. "Numerical Study on the Flow and Heat Transfer Characteristics of a Second Throat Exhaust Diffuser According to Variations in Operating Pressure and Geometric Shape." Energies 14, no. 3 (January 20, 2021): 532. http://dx.doi.org/10.3390/en14030532.

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A numerical study was conducted to investigate the flow and heat transfer characteristics of a supersonic second throat exhaust diffuser for high-altitude simulations. The numerical results were satisfactorily validated by the experimental results. A subscale diffuser using nitrogen was utilized to investigate starting pressure and pressure variation in the diffuser wall. Based on the validated numerical method, the flow and heat transfer characteristics of the diffuser using burnt gas were evaluated by changing operating pressure and geometric shape. During normal diffuser operation without cooling, high-temperature regions of over 3000 K appeared, particularly near the wall and in the diffuser diverging section. After cooling, the flow and pressure distribution characteristics did not differ significantly from those of the adiabatic condition, but the temperature in the subsonic flow section decreased by more than 1000 K. Furthermore, the tendency of the heat flux from the diffuser internal flow to the wall was similar to that of the pressure variations, and it increased with operating pressure. It was confirmed that the heat fluxes of the supersonic and subsonic flows in the diffuser were proportional to the operating pressure to the 0.8 and −1.7 power, respectively. In addition, in the second throat region after separation, the heat flux could be scaled to the Mach number ratio before and after the largest oblique shock wave because the largest shock train affected the heat flux of the diffuser wall.

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8

Aranake, Aniket, Jin Gyu Lee, Doyle Knight, Russell M. Cummings, John Cox, Micah Paul, and Aaron R. Byerley. "Automated Design Optimization of a Three-Dimensional Subsonic Diffuser." Journal of Propulsion and Power 27, no. 4 (July 2011): 838–46. http://dx.doi.org/10.2514/1.50522.

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9

Casartelli, E., A. P. Saxer, and G. Gyarmathy. "Numerical Flow Analysis in a Subsonic Vaned Radial Diffuser With Leading Edge Redesign." Journal of Turbomachinery 121, no. 1 (January 1, 1999): 119–26. http://dx.doi.org/10.1115/1.2841219.

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The flow field in a subsonic vaned radial diffuser of a single-stage centrifugal compressor is numerically investigated using a three-dimensional Navier–Stokes solver (TASCflow) and a two-dimensional analysis and inverse-design software package (MISES). The vane geometry is modified in the leading edge area (two-dimensional blade shaping) using MISES, without changing the diffuser throughflow characteristics. An analysis of the two-dimensional and three-dimensional effects of two redesigns on the flow in each of the diffuser subcomponents is performed in terms of static pressure recovery, total pressure loss production, and secondary flow reduction. The computed characteristic lines are compared with measurements, which confirm the improvement obtained by the leading edge redesign in terms of increased pressure rise and operating range.

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10

YOSHIKAWA, Hisataka, Makoto YAMAMOTO, and Sinji HONAMI. "Numerical Simulation of Subsonic Diffuser for Supersonic Air-Intake(Effects of Blowing on Diffuser Performance)." Transactions of the Japan Society of Mechanical Engineers Series B 65, no. 631 (1999): 876–81. http://dx.doi.org/10.1299/kikaib.65.876.

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11

M. Salih, Tawfeeq Wasmi. "Predicting Unsteady Flow Parameters in a Subsonic Air Diffuser Using MacCormack’s Explicit Method." Wasit Journal of Engineering Sciences 7, no. 1 (April 15, 2019): 1–10. http://dx.doi.org/10.31185/ejuow.vol7.iss1.109.

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A numerical procedure is presented to predict the flow characteristics inside a subsonic diffuser by solving Navier-Stokes' equations, using MacCormack’s explicit method. The flow is assumed to be viscous, compressible, unsteady and two-dimensional. The grid model suggested for the diffuser has 20 points in the horizontal direction and 30 points in the vertical direction. The numerical solution has shown reasonable results with a 2D variation of flow properties inside the diffuser and the steady state solution can be satisfied by 600-900 loops only. The obtained results of the present study are compared with those obtained by using a numerical code of National Project for Application-oriented Research in CFD (NPARC) as well as those obtained from a previous experimental study and give an acceptable range of errors (about ± 15%).

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12

Jenkins, Richard C., and Albert L. Loeffler. "Modeling of subsonic flow through a compact offset inlet diffuser." AIAA Journal 29, no. 3 (March 1991): 401–8. http://dx.doi.org/10.2514/3.10592.

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13

Nordin, Normayati, Zainal Ambri Abdul Karim, Safiah Othman, and Vijay R. Raghavan. "Effect of Varying Inflow Reynolds Number on Pressure Recovery and Flow Uniformity of 3-D Turning Diffuser." Applied Mechanics and Materials 699 (November 2014): 422–28. http://dx.doi.org/10.4028/www.scientific.net/amm.699.422.

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Various diffuser types characterized by the geometry are introduced in the flow line to recover the energy. A 3-D turning diffuser is a type of diffuser that its cross-section diffuses in all 3 directions of axes, i.e. x, y and z. In terms of applicability, a 3-D turning diffuser offers compactness and more outlet-inlet configurations over a 2-D turning diffuser. However, the flow within a 3-D turning diffuser is expected to be more complex which susceptible to excessive losses. As yet there is no established guideline that can be referred to choose a 3-D turning diffuser with an optimum performance. This paper aims to investigate the effects of varying inflow Reynolds number (Rein) on the performance of 3-D turning diffuser with 90o angle of turn. The outlet pressure recovery (Cp) and flow uniformity (σu) of 3-D turning diffuser with an area ratio (AR = 2.16) and outlet-inlet configurations (W2/W1 = 1.44, X2/X1 = 1.5), operated at inflow Reynolds number of Rein = 5.786E+04 - 1.775E+05 have been experimentally tested. The experimental rig was developed by incorporating several features of low subsonic wind tunnel. This was mainly to produce a perfect fully developed and uniform flow entering diffuser. Particle image velocimetry (PIV) was used to examine the flow quality, and a digital manometer was used to measure the average static pressure of the inlet and outlet of turning diffuser. There is a promising improvement in terms of flow uniformity when a 3-D turning diffuser is used instead of a 2-D turning diffuser with the same AR. An unexpected trend found with a drop of pressure recovery at maximum operating condition of Rein = 1.775E+05 shall require further investigations. The results obtained from this study will be in future used to validate the numerical codes. Upon successful validation, several other configurations will be numerically tested in order to establish the guidelines in the form of mathematical models.

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14

Nordin, Normayati, Zainal Ambri Abdul Karim, Safiah Othman, and Vijay R. Raghavan. "Design and Development of Low Subsonic Wind Tunnel for Turning Diffuser Application." Advanced Materials Research 614-615 (December 2012): 586–91. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.586.

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In practice, it is basically difficult even with controlled measurement environment to acquire a steady, uniform and fully developed flow. The flow entering diffuser was severely distorted despite a sufficient hydrodynamic entrance length already introduced. This was mainly due to the imperfect joining of duct and the abrupt change of the inlet cross-section applied. In this study, several basic features of a low subsonic wind tunnel, i.e. a centrifugal blower with 3-phase inverter, a settling chamber, screens and a contraction cone, are designed and developed for a turning diffuser application in order to improve the flow quality. The flow profiles are examined using Pitot static probe at five measurement points within the range of inflow Reynolds number, Rein= 5.786E+04-1.775E+05. The steady, uniform and fully developed turbulent flow profiles with an average deviation with theory of about 3.5% are obtained. This proves that a good flow quality could be produced by means of incorporating some basic features of a low subsonic wind tunnel to the system.

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15

Saboohi, Zoheir. "Design of a Diffuser for a Subsonic Wind Tunnel Using CFD." Journal of Space Science and Technology 12, no. 3 (September 23, 2019): 1–13. http://dx.doi.org/10.30699/jsst.2019.119182.

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16

Lefantzi, Sophia, and Doyle D. Knight. "Automated Design Optimization of a Three-Dimensional S-Shaped Subsonic Diffuser." Journal of Propulsion and Power 18, no. 4 (July 2002): 913–21. http://dx.doi.org/10.2514/2.6017.

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17

Chyu, W. J., and D. P. Bencze. "Navier-Stokes simulation of flow through a highly contoured subsonic diffuser." International Journal for Numerical Methods in Engineering 34, no. 2 (March 30, 1992): 473–83. http://dx.doi.org/10.1002/nme.1620340207.

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18

Wang, Bin, and Qiang Wang. "Numerical Optimization of Electromagnetic Performance and Aerodynamic Performance for Subsonic S-Duct Intake." Aerospace 9, no. 11 (October 28, 2022): 665. http://dx.doi.org/10.3390/aerospace9110665.

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In order to improve the performance of subsonic unmanned aerial vehicle (UAV), a knapsack S-duct intake has been designed. The influences of an S-bend diffuser on aerodynamic performance and electromagnetic performance were analyzed firstly. The viscous flow field has been simulated by solving Favre averaged Navier–Stokes equations using a shear stress transport (SST) k-ω turbulence model. The surface current has been simulated by solving Maxwell equations using a multi-level fast multipole method (MLFMM). The multi-objective optimization of the S-duct intake was studied by using the diffuser as the optimized object. The parametric expression of the diffuser model was realized using the fourth order function geometric representation technique. The efficient model based on the Kriging model and non-dominated sorting genetic algorithm-Ⅱ (NSGA-Ⅱ) were used to accelerate the optimization progress. By analyzing the results of an optimal intake chosen from the Pareto front, the total pressure distortion (TPD) index DC60 has decreased by 0.24 at the designed Mach number of 0.9, and the average Radar Cross Section (RCS) has decreased by 2db at the frequency of 3GHz. The optimized S-duct intake could have both excellent aerodynamic performance and electromagnetic performance at various complex conditions.

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19

Hamada, Khalaf I. "Numerical Validation on The Performance of A Two Dimensional Curved Diffuser." Tikrit Journal of Engineering Sciences 16, no. 1 (March 31, 2009): 105–20. http://dx.doi.org/10.25130/tjes.16.1.08.

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This paper deals with the investigation of the characteristic of subsonic viscous flow through a curved diffuser numerically with commercial code for computational fluid dynamics (CFD) Fluent Inc. version 6.3. The diffuser flow is a two-dimensional, turbulent, incompressible and fully developed. The investigations are based on the Spalart-Allmaras turbulent model. A 2-D quadrilateral grid is generated by the grid generator GAMBIT. Obtained results are compared with the available experimental data and found to give good agreement. The effects of curvature angle, area ratio and adding tail channel with constant area on the diffuser performance and flow pattern are studied and revealed by the pressure contour, velocity vector, and variation of the pressure recovery factor for all above mentioned parameters.

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20

Dvořák, Václav. "Air to Air Ejector with Various Divergent Mixing Chambers." Applied Mechanics and Materials 493 (January 2014): 50–55. http://dx.doi.org/10.4028/www.scientific.net/amm.493.50.

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The article deals with experimental investigation of subsonic air to air ejector with various configurations of the mixing chamber and the diffuser. A constant mixing chamber, 2° and 4° divergent mixing chambers and 6° diffuser were applied to find differences in the mixing process. Characteristics of the ejector, static pressure distributions and pressure fluctuations were measured to find how the different shape of the mixing chamber affect the efficiency of mixing processes. Pressure fluctuation increased rapidly while the ejection ratio was higher than 1.25 and the highest efficiency of the ejector was obtained when using configuration 4-4-6.

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21

King, Christopher D., Semih M. Ölçmen, Muhammad A. R. Sharif, and Tom Presdorf. "Computational Analysis of Diffuser Performance for Subsonic Aerodynamic Research Laboratory Wind Tunnel." Engineering Applications of Computational Fluid Mechanics 7, no. 4 (January 2013): 419–32. http://dx.doi.org/10.1080/19942060.2013.11015482.

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22

WATANABE, Yasushi, and Akira MURAKAMI. "Effect of Area Distribution and Centerline Configuration on Aerodynamic Performance of Subsonic Diffuser." Transactions of the Japan Society of Mechanical Engineers Series B 70, no. 696 (2004): 1999–2004. http://dx.doi.org/10.1299/kikaib.70.1999.

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23

Sakamoto, Kazuyuki, Shinji Honami, Kimio Sakata, Akira Murakami, and Shigemi Shindo. "An Experimental Study on the Subsonic Diffuser with a Shock Wave at the Inlet." Transactions of the Japan Society of Mechanical Engineers Series B 60, no. 575 (1994): 2261–66. http://dx.doi.org/10.1299/kikaib.60.2261.

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24

Tsukanov, Ruslan. "Design of circular air intakes for subsonic turbofans." Aerospace technic and technology, no. 4 (August 11, 2022): 4–13. http://dx.doi.org/10.32620/aktt.2022.4.01.

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The subject matter of this article is the process of subsonic air intake shaping for high-bypass ratio turbofan at the airplane preliminarily designing stage. The goal was to improve a mathematical model of V. I. Polikovskii method of subsonic air intake shaping for high-bypass ratio turbofan. The tasks are to consider the presence of cant of inlet cross-section, required to perform effective operation at airplane cruising angle-of-attacks; to increase the radius of curvature of the air intake lip to provide air flow near it without flow separation, which was definitely determined and could not be increased in the existing method; to improve constant length velocity gradient law (used in this method) so that too large duct expansion angles near the air intake outlet cross-section can be avoided; to consider the engine inlet spinner presence. The methods used are analytical and digital mathematical methods, implemented in MathCAD and Microsoft Visual Studio systems. The following results were obtained: based on the proposed method, new calculation module for the Power Unit software version 11.8 has been developed (С-language Win32 UNICODE application) with a friendly user interface. Conclusions. The scientific novelty of the results obtained is as follows: 1) mathematical model (algorithm and its program implementation) for circular turbofan air intake shaping has been improved considering cant of the inlet cross-section, air intake lip rounding with two radiuses, presence of engine inlet spinner, and zero expansion angles in the diffuser outlet cross-section; 2) adequacy of calculation results using the improved mathematical model is shown using comparison with shapes of circular turbofan air intakes, developed by the leading aviation companies.

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25

Wang, Yi, Qingkuo Li, Huan Bai, Xueqi Zhou, and Xin’gen Lu. "Numerical Investigation of a Centrifugal Compressor with a Pre-Compression Wedge Diffuser under High Subsonic Conditions." Journal of Thermal Science 29, no. 4 (July 4, 2020): 945–54. http://dx.doi.org/10.1007/s11630-020-1332-0.

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26

Trébinjac, I., N. Bulot, and N. Buffaz. "Analysis of the flow in a transonic centrifugal compressor stage from choke to surge." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 225, no. 7 (August 24, 2011): 919–29. http://dx.doi.org/10.1177/0957650911411537.

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Numerical and experimental investigations were conducted in a transonic centrifugal compressor stage composed of a backswept splittered unshrouded impeller and a vaned diffuser. Unsteady three-dimensional simulations were performed with the code elsA that solves the turbulent-averaged Navier–Stokes equations, at three operating points: choked flow, peak efficiency, and near surge. Numerical results were validated with experimental data coming from laser Doppler anemometry and unsteady pressure measurements. This article focuses on the change in flow structures when the operating point moves from choke to surge. The main changes in the impeller consist in an enlargement of the wake (of the jet-wake flow structure) and an increase in the exit time-averaged flow angle. Consequently, in the diffuser passage, the main flow trajectory moves towards the vane pressure side, and the boundary layer separation transfers from pressure side to suction side. The interaction between the vane bow shock wave and the impeller blade leads to pressure waves α+, which propagate in the diffuser passage. These pressure waves generate alternately opposite and favourable pressure gradients, which drive the boundary layers to periodic separation. From choke to surge, the intensity of the pressure waves α+ increases. The interaction also leads to subsonic pockets Г, which are torn out from the vane-leading edge bow shock and swept along the vane suction side. The induced change in the shock shape and location combined with the severe hub/suction side corner separation are thought to be at the origin of the surge inception.

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27

Idris, Imam Maulana. "RANCANG BANGUN TEROWONGAN ANGIN (WIND TUNNEL) TIPE SUBSONIC DENGAN TEST SECTION 0,2 X 0,2 M UNTUK ALAT PERAGA MEKANIKA FLUIDA." Mechonversio: Mechanical Engineering Journal 2, no. 2 (December 18, 2019): 19. http://dx.doi.org/10.51804/mmej.v2i2.614.

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Wind tunnel merupakan suatu alat yang berfungsi untuk mengetahui suatu kondisi udara yang mengenai benda padat. wind tunnel sering digunakan dalam berbagai bidang seperti aerodinamika, teknik, dan fisika, melalui bidang bidang tersebut terowongan angin memegang peranan penting. Karena di labolatorium teknik mesin belum mempunyai wind tunnel, padahal peranannya sangat dibutuhkan untuk penelitian mahasiswa. Tujuan yang ingin di capai dalam rancang bangun ini adalah sebagai alat penunjang praktikum di labolatorium Universitas Ma’arif Hasyim Latief dalam bidang ilmu aerodinamika ataupun dalam perkembangan dunia otomotif dengan menyesuaikan dengan wind tunnel yang sudah pernah dibuat dan memenuhi standart. Rancang bangun ini menghasilkan wind tunnel tipe subsonic dengan test section 0,2 X 0,2m yang mempunyai ukuran keseluruan 2,42m X 0,61m X 1,11m, dengan panjang Test Section 0,452m, Diffuser 0,909m, Contraction 0,508m, Hanycome 0,096m, dan wind tunnel yang telah dibuat dapat bekerja dengan baik.

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28

Tsukanov, Ruslan. "Designing of non circular air intakes for subsonic gas-turbine engines." Aerospace Technic and Technology, no. 6 (November 27, 2023): 4–14. http://dx.doi.org/10.32620/aktt.2022.6.01.

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The subject matter of the article is the process of subsonic air intake shaping for gas-turbine engines at the airplane preliminarily design stage. The goal is to develop a mathematical model for non-circular air intake shaping for gas-turbine engines on the base of V. I. Polikovskii method of subsonic air intake shaping for high-bypass ratio turbofan. The tasks to be solved are: to consider the possibility of non-circular shape of the external outline of the engine nacelle; to take into account the possibility of non-circular shape of the internal air intake duct (in the first approximation, the shape of internal air intake duct cross-section is defined in the form of a rectangular with possible four different radiuses in its corners); to consider the engine inlet spinner presence. The methods used are: analytical and digital mathematical methods, implemented in MathCAD and Microsoft Visual Studio systems. The following results were obtained: On the base of the proposed method, new calculation module for the Power Unit software version 11.8 has been developed (С-language Win32 UNICODE application) having a friendly user interface. Conclusions. The scientific novelty of the results obtained is as follows: 1) mathematical model (algorithm and its program implementation) for non-circular air intake shaping for gas-turbine engines has been developed considering non-circular shape of the external outline of the engine nacelle, non-circular shape of the air intake duct internal outline, presence of engine inlet spinner, and zero expansion angle in the diffuser outlet cross-section; 2) adequacy of calculation results by the developed mathematical model is shown by means of comparison with the shape of real air intake, developed by the Antonov Company. For the following improvement of the mathematical model, it is desirable to add the possibility of considering S‑shape of the air intake duct, defining its length from designer’s considerations, defining a bigger radius of curvature of the air intake lip, and considering the presence of boundary layer bleeding devices in front of the air intake.

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29

MIURA, Satoshi, Akira MURAKAMI, and Shinji HONAMI. "An Experimental Stydy of the Effects of Blowing on the Performance of Subsonic Diffuser for a Supersonic Air-Intake." Transactions of the Japan Society of Mechanical Engineers Series B 65, no. 629 (1999): 185–90. http://dx.doi.org/10.1299/kikaib.65.185.

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30

Ibrahim, I. H., E. Y. K. Ng, K. Wong, and R. Gunasekaran. "Effects of centerline curvature and cross-sectional shape transitioning in the subsonic diffuser of the F-5 fighter jet." Journal of Mechanical Science and Technology 22, no. 10 (October 2008): 1993–97. http://dx.doi.org/10.1007/s12206-008-0744-7.

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31

Natarajan, Mahesh, Jonathan B. Freund, and Daniel J. Bodony. "Actuator selection and placement for localized feedback flow control." Journal of Fluid Mechanics 809 (November 18, 2016): 775–92. http://dx.doi.org/10.1017/jfm.2016.700.

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The selection and placement of actuators and sensors to control compressible viscous flows is addressed by developing a novel methodology based upon the eigensystem structural sensitivity of the linearized evolution operator appropriate for linear feedback control. Forward and adjoint global modes are used to construct a space of possible perturbations to the linearized operator, which yields a small optimization problem for selecting the parameters that best achieve the control objective, including where they should be placed. The method is demonstrated by informing actuation to suppress amplification of the instabilities in boundary layer separation in a high-subsonic diffuser. Complete stabilization is observed in the separated shear layer for short downstream distances at modest Reynolds number. Higher Reynolds numbers and longer distances are expected to be more challenging to stabilize; here the control informed by the procedure still substantively suppresses amplification of instabilities. It is also demonstrated that more complex actuator–sensor selections may not yield superior controllers.

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32

Roduner, Christian, Peter Kupferschmied, Pascal Ko¨ppel, and Georg Gyarmathy. "On the Development and Application of the Fast-Response Aerodynamic Probe System in Turbomachines—Part 2: Flow, Surge, and Stall in a Centrifugal Compressor." Journal of Turbomachinery 122, no. 3 (February 1, 1999): 517–26. http://dx.doi.org/10.1115/1.1303827.

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The present paper, Part 2 of a trilogy, is primarily focussed on demonstrating the capabilities of a fast-response aerodynamic probe system configuration based on the simplest type of fast-response probe. A single cylindrical probe equipped with a single pressure sensor is used to measure absolute pressure and both velocity components in an essentially two-dimensional flow field. The probe is used in the pseudo-three-sensor mode (see Part 1). It is demonstrated that such a one-sensor probe is able to measure high-frequency rotor-governed systematic fluctuations (like blade-to-blade phenomena) alone or in combination with flow-governed low-frequency fluctuations as rotating stall (RS) and mild surge (MS). However, three-sensor probes would be needed to measure stochastic (turbulence-related) or other aperiodic velocity transients. The data shown refer to the impeller exit and the vaned diffuser of a single-stage high-subsonic centrifugal compressor. Wall-to-wall probe traverses were performed at the impeller exit and different positions along the vaned diffuser for different running conditions. The centrifugal compressor was operated under stable as well as unstable (pulsating or stalled) running conditions. The turbomachinery-oriented interpretation of these unsteady flow data is a second focus of the paper. A refined analysis of the time-resolved data will be performed in Part 3, where different spatial/temporal averaging methods are compared. Two different averaging methods were used for the data evaluation: impeller-based ensemble-averaging for blade-to-blade systematic fluctuations (with constant period length at a constant shaft speed), and flow-based class averaging for the relatively slow MS and RS with slightly variable period length. Due to the ability of fast-response probes to simultaneously measure velocity components and total and static pressure, interesting insights can be obtained into impeller and diffuser channel flow structures as well as into the time behavior of such large-domain phenomena as RS and MS. [S0889-504X(00)01103-X]

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Olasek, Krzysztof, Maciej Karczewski, Michal Lipian, Piotr Wiklak, and Krzysztof Józwik. "Wind tunnel experimental investigations of a diffuser augmented wind turbine model." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 7 (September 5, 2016): 2033–47. http://dx.doi.org/10.1108/hff-06-2015-0246.

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Purpose A solution to increase the energy production rate of the wind turbine is proposed by forcing more air to move through the turbine working section. This can be achieved by equipping the rotor with a diffusing channel ended with a brim (diffuser augmented wind turbine – DAWT). The purpose of this paper is to design an experimental stand and perform the measurements of velocity vector fields through the diffuser and power characteristic of the wind turbine. Design/methodology/approach The experiments were carried out in a small subsonic wind tunnel at the Institute of Turbomachinery, Lodz University of Technology. An experimental stand design process as well as measurement results are presented. Model size sensitivity study was performed at the beginning. The experimental campaign consisted of velocity measurements by means of particle image velocimetry (PIV) and pneumatic pitot probe as well as torque and rotational velocity measurements. Findings Characteristics (power coefficient vs tip speed ratio) of the bare and shrouded wind turbine were obtained. The results show an increase in the wind turbine power up to 70-75 per cent by shrouding the rotor with a diffuser. The mechanisms responsible for such a power increase were well explained by the PIV and pneumatic measurement results revealing the nature of the flow through the diffuser. Research limitations/implications Experimental stand for wind turbine rotor testing is of a preliminary character. Most optimal methodology for obtaining power characteristic should be determined now. Presented results can serve as good input for choice of stable and reliable control system of wind turbine operational parameters. Practical implications A 3 kW DAWT is being developed at the Institute of Turbomachinery, Lodz University of Technology. Aim of the study is to design a compact and smart wind turbine optimised for low wind speed conditions. Developed wind turbine has a potential to be used as an effective element within a net of distributed generation, e.g. for domestic use. Originality/value Research carried out is the continuation of theoretical study began in 1970s. It was also inspired by practical solutions proposed by Japanese researchers few years ago. Presented paper is the summary of work devoted to optimisation of the DAWT for wind conditions in the region. Original solution has been applied, e.g. for experimental stand design (3D printing application).

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Zhang, Le, Zhou Zhou, and Hong Bo Wang. "Conformal s-Shaped Inlet Design and Flow Field Characteristics of Flying Wing Unmanned Aerial Vehicle." Advanced Materials Research 940 (June 2014): 295–99. http://dx.doi.org/10.4028/www.scientific.net/amr.940.295.

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According to the stealth and conformal requirement of flying wing UAV(Unmanned Aerial Vehicle),an dorsal subsonic S-shaped inlet with long diffuser and large offset is designed. In the light of the characteristics of the inlet, new area distribution is created. In the study, the model with power system and the other model whose pipeline connected are established. The coupled numerical simulation is also carried out on the inflow/outflow integrated for flying wing UAV, and it is applied to study the longitudinal aerodynamic performance of UAV and the flow characteristics of inlet under different flight conditions. Results indicate: The longitudinal aerodynamic performance of the model with power system is close to the model with pipeline connected, but the moment characteristic of the former is better; The inlet characteristics are similar when Ma=0.5 and Ma=0.6; As the mach number increasing, the inlet performance decreases rapidly, Especially at the Ma = 0.7, there is a large low-pressure dominated region at the small angle of attack α = 2°, which leads to the total pressure recovery coefficient decreasing rapidly and the flow distortion increasing obviously.

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35

HOWE, M. S. "Indirect combustion noise." Journal of Fluid Mechanics 659 (July 20, 2010): 267–88. http://dx.doi.org/10.1017/s0022112010002466.

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An analysis is made of the noise generated during the passage of quiescent temperature/entropy inhomogeneities through regions of rapidly accelerated mean flow. This is an important source of jet engine core noise. Bake et al. (J. Sound Vib., vol. 326, 2009, pp. 574–598) have used an ‘entropy wave generator’ coupled with a converging–diverging nozzle to perform a series of canonical measurements of the sound produced when the inhomogeneity consists of a nominally uniform slug of hot gas. When flow separation and jet formation occur in the diffuser section of the nozzle, it is shown in this paper that the vortex sound generated by the jet is strongly correlated with the entropy noise produced by the slug and that the overall noise level is significantly reduced. Streamwise ‘stretching’ of the hot slug during high subsonic acceleration into the nozzle and the consequent attenuation of the entropy gradient in the nozzle are shown to significantly decrease the effective rate at which indirect combustion noise increases with the Mach number. Numerical predictions indicate that this is responsible for the peak observed by Bake et al. in the entropy-generated sound pressure at a nozzle Mach number near 0.6.

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Kang, Weijia, Zhansheng Liu, Jiangbo Lu, Yu Wang, and Yanyang Dong. "A Numerical Study for Flow Excitation and Performance of Rampressor Inlet considering Rotor Motion." Shock and Vibration 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/963234.

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A unique supersonic compressor rotor with high pressure ratio, termed the Rampressor, is presented by Ramgen Power Systems, Inc. (RPS). In order to obtain the excitation characteristic and performance of Rampressor inlet flow field under external excitation, compression inlet flow of Rampressor is studied with considering Rampressor rotor whirling. Flow excitation characteristics and performance of Rampressor inlet are analyzed under different frequency and amplitude of Rampressor rotor whirling. The results indicate that the rotor whirling has a significant effect for flow excitation characteristics and performance of Rampressor inlet. The effect of rotor whirling on the different inlet location excitation has a definite phase difference. Inlet excitation becomes more complex along with the inlet flow path. More frequency components appear in the excitation spectrum of Rampressor inlet with considering Rampressor rotor whirling. The main frequency component is the fundamental frequency, which is caused by the rotor whirling. Besides the fundamental frequency, the double frequency components are generated due to the coupling between inlet compression flow of Rampressor rotor and rotor whirling, especially in the subsonic diffuser of Rampressor rotor inlet. With the increment of rotor whirling frequency and whirling amplitude, the complexity of Rampressor inlet excitation increases, and the stability of Rampressor inlet performance deteriorates.

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Vinod. L et al.,, Vinod L. et al ,. "The CFD Analysis of Subsonic Flow Around Struts of Airfoil and Cylindrical Shape Attached to a Conical Diffuser at Exhaust of a Gas Turbine Engine." International Journal of Mechanical and Production Engineering Research and Development 9, no. 4 (2019): 943–54. http://dx.doi.org/10.24247/ijmperdaug201996.

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G, Andi Tri. "ANALISIS DAN PERHITUNGAN PADA DAYA MOTOR UNTUK TEROWONGAN ANGIN (WIND TUNNEL) TIPE SUBSONIC DENGAN TEST SECTION 0,2 X 0,2 M UNTUK ALAT PERAGA MEKANIKA FLUIDA SKALA LABOLATORIUM." Mechonversio: Mechanical Engineering Journal 2, no. 2 (December 18, 2019): 25. http://dx.doi.org/10.51804/mmej.v2i2.615.

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Aerodinamika yaitu salah satu bagian dari ilmu dinamika fluida yang mempelajari tentang gaya yang bekerja kepada suatu objek benda yang berada di dalam suatu aliran fluida. Pemecahan pada persoalan aerodinamika yang umumnya melibatkan penghitungan berbagai sifat pada aliran yang terjadi, semacam kecepatan, tekanan, temperatur, maupungaya masa jenis, sebagai suatu fungsi terhadap ruang dan waktu. Dengan mempelajari model - model aliran yang ada, maka akan memungkinkan untuk menghitung maupun memperkirakan momen dan gaya bekerja pada suatu objek yang berada pada aliran tersebut. Laporan secara eksperimen yang berguna dalam pemecahan permasalahan aerodinamika bisa didapat melalui berbagai macam metode, dan salah satu metode tersebut yaitu dengan menggunakan wind tunnel.Tujuan memperoleh angka air volume / CMH yang dibutuhkan pengujian pada (test section) di rangkaian terbuka wind tunnel. Mengetahui total keseluruhan kerugian pada tiap bagian rangkaian terbuka wind tunnel. Mengetahui dari hasil perhitungan daya motor pada fan yang benar dan sesuai.Dari perhitungan yang telah dilakukan maka nilai minimal air volume yang diperlukan pada bagian test section sebesar 2880,14 CMH (Cubic Meter Hour). Analisa dari perhitungan Energy losses (kerugian energi) dari setiap komponen dalam rangkaian terbuka wind tunnel yaitu settling chamber ( untuk nilai Honeycomb nilai K0 = 0,004687 dan screen nilai K1 = 0,004687) , contraction dengan nilai K2 = 0,02745, test section nilai K3 = 0,0675 , Diffuser nilai K4 = 0,72962, dan saluran discharge nilai K5 = 0,1667887. Maka total dari keseluruhan nilai tersebut dijumlahkan Ktotal = 0,20014656. Perhitungan nilai daya motor yang dibutuhkan pada hasil perhitungan pada BAB 4 sebesar 233,51 W -> ½ HP.

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Wood, J. R., J. F. Schmidt, R. J. Steinke, R. V. Chima, and W. G. Kunik. "Application of Advanced Computational Codes in the Design of an Experiment for a Supersonic Throughflow Fan Rotor." Journal of Turbomachinery 110, no. 2 (April 1, 1988): 270–79. http://dx.doi.org/10.1115/1.3262191.

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Increased emphasis on sustained supersonic or hypersonic cruise has revived interest in the supersonic throughflow fan as a possible component in advanced propulsion systems. Use of a fan that can operate with a supersonic inlet axial Mach number is attractive from the standpoint of reducing the inlet losses incurred in diffusing the flow from a supersonic flight Mach number to a subsonic one at the fan face. The data base for components of this type is practically nonexistent; therefore, in order to furnish the required information for assessment of this type fan, a program has been initiated at the NASA Lewis Research Center to design, build, and test a fan rotor that operates with supersonic axial velocities from inlet to exit. This paper describes the design of the experiment using advanced computational codes to calculate the unique components required. The fan rotor has constant hub and tip radii and was designed for a pressure ratio of 2.7 with a tip speed of 457 m/s. The rotor was designed using existing turbomachinery design and analysis codes modified to handle fully supersonic axial flow through the rotor. A two-dimensional axisymmetric throughflow design code plus a blade element code were used to generate fan rotor velocity diagrams and blade shapes. A quasi-three-dimensional, thin shear layer Navier–Stokes code was used to assess the performance of the fan rotor blade shapes. The final design was stacked and checked for three-dimensional effects using a three-dimensional Euler code interactively coupled with a two-dimensional boundary layer code. A translating nozzle was designed to produce a uniform flow parallel to the fan up to the design axial Mach number of 2.0. The nozzle was designed with the three-dimensional Euler/interactive boundary layer code. The nozzle design in the expansion region was analyzed with a three-dimensional parabolized viscous code, which corroborated the results from the Euler code. A translating supersonic diffuser was designed using these same codes.

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Alvarenga, Meiriele Abreu, Claudia Regina de Andrade, and Edson Luiz Zaparoli. "Compressible Subsonic Flow in Gas Turbine Annular Diffusers." International Review of Mechanical Engineering (IREME) 10, no. 7 (November 30, 2016): 474. http://dx.doi.org/10.15866/ireme.v10i7.8994.

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NAKAGAWA, Koji, Hideo NISHIDA, Hiromi KOBAYASHI, Takeo TAKAGI, and Haruki SAKAI. "Study of high subsonic vaned diffusers for centrifugal compressors." Transactions of the Japan Society of Mechanical Engineers Series B 57, no. 533 (1991): 166–71. http://dx.doi.org/10.1299/kikaib.57.166.

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Wysocki, W., and Z. Kazimierski. "Analysis of Subsonic Transitory Stalled Flows in Straight-Walled Diffusers." Journal of Fluids Engineering 108, no. 2 (June 1, 1986): 222–26. http://dx.doi.org/10.1115/1.3242566.

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A simple, semi-empirical procedure is presented for computation of subsonic, turbulent, attached, and transitory-stalled flows in straight-walled diffusers with plenum exit. The procedure employs a zonal model while using the concept of a dividing streamline and integral methods for boundary layer calculations on diverging and parallel side walls. The dividing streamline separates the transitory stall zone, having zero mass flow rate, from the effective flow channel. The procedure predicts the pressure as a function of streamwise location with modest computation times, typically a few minutes on a personal computer and can be useful in design calculations.

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Kashkin, Yu F., A. E. Konovalov, S. Yu Krasheninnikov, D. A. Lyubimov, D. E. Pudovikov, and V. A. Stepanov. "Experimental and numerical investigation of separated flows in subsonic diffusers." Fluid Dynamics 44, no. 4 (August 2009): 555–65. http://dx.doi.org/10.1134/s0015462809040097.

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Lou, Fangyuan, John Charles Fabian, and Nicole Leanne Key. "Interpreting Aerodynamics of a Transonic Impeller from Static Pressure Measurements." International Journal of Rotating Machinery 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/7281691.

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This paper investigates the aerodynamics of a transonic impeller using static pressure measurements. The impeller is a high-speed, high-pressure-ratio wheel used in small gas turbine engines. The experiment was conducted on the single stage centrifugal compressor facility in the compressor research laboratory at Purdue University. Data were acquired from choke to near-surge at four different corrected speeds (Nc) from 80% to 100% design speed, which covers both subsonic and supersonic inlet conditions. Details of the impeller flow field are discussed using data acquired from both steady and time-resolved static pressure measurements along the impeller shroud. The flow field is compared at different loading conditions, from subsonic to supersonic inlet conditions. The impeller performance was strongly dependent on the inducer, where the majority of relative diffusion occurs. The inducer diffuses flow more efficiently for inlet tip relative Mach numbers close to unity, and the performance diminishes at other Mach numbers. Shock waves emerging upstream of the impeller leading edge were observed from 90% to 100% corrected speed, and they move towards the impeller trailing edge as the inlet tip relative Mach number increases. There is no shock wave present in the inducer at 80% corrected speed. However, a high-loss region near the inducer throat was observed at 80% corrected speed resulting in a lower impeller efficiency at subsonic inlet conditions.

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Le, M., I. Hassan, and N. Esmail. "DSMC Simulation of Subsonic Flows in Parallel and Series Microchannels." Journal of Fluids Engineering 128, no. 6 (May 8, 2006): 1153–63. http://dx.doi.org/10.1115/1.2354525.

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Flows in uniform, parallel, and series microchannels have been investigated using the direct simulation Monte Carlo (DSMC) method. For the uniform microchannel cases, at higher pressure ratio, mixed Kn-regime flows were observed, where the Knudsen number (Kn) varies from below 0.1 to above 0.1. Also, the higher pressure ratio makes the flow accelerate more as the flow develops through the uniform microchannel. In order to examine the heat transfer characteristics between the wall and the bulk flow, a linear temperature distribution was imposed on the wall. Most of the wall heat flux occurs within the channel entrance region while it remains a constant with a slight magnitude along the rest of the channel wall. For the series microchannel cases, the computational domain was established by adding three surfaces and excluding one region from the rectangular domain. Diffuse effects were observed near the interface of the two segments, where the flow upstream the interface can be either heated or cooled by the flow downstream depending on their temperature difference. In addition, the effect of the gas species was investigated by conducting the simulation using helium and argon respectively. It can be found that the speed of the gas with lighter molecular mass is much higher than that of the heavier gas. The computational domain of the parallel microchannel was established similarly to that of the series microchannel. Under a certain pressure ratio, more pressure drop occurs in the parallel parts as the gap height increases. The recirculation phenomenon was observed after the gap wall between the two parallel parts and was evaluated quantitatively in the present study by defining a parameter called the developing coefficient. The gap height between the two parallel parts has only slight effect of the flow development.

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El Hassan, Mouhammad, and Laurent Keirsbulck. "Passive control of deep cavity shear layer flow at subsonic speed." Canadian Journal of Physics 95, no. 10 (October 2017): 894–99. http://dx.doi.org/10.1139/cjp-2016-0822.

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Passive control of the flow over a deep cavity at low subsonic velocity is considered in the present paper. The cavity length-to-depth aspect ratio is L/H = 0.2. particle image velocimetry (PIV) measurements characterized the flow over the cavity and show the influence of the control method on the cavity shear layer development. It is found that both the “cylinder” and the “shaped cylinder”, placed upstream from the cavity leading edge, result in the suppression of the aero-acoustic coupling and highly reduce the cavity noise. It should be noted that the vortical structures impinge at almost the same location near the cavity downstream corner with and without passive control. The present study allows to identify an innovative passive flow control method of cavity resonance. Indeed, the use of a “shaped cylinder” presents similar suppression of the cavity resonance as with the “cylinder” but with less impact on the cavity flow. The “shaped cylinder” results in a smaller shear layer growth than the cylinder. Velocity deficiency and turbulence levels are less pronounced using the “shaped cylinder”. The “cylinder” tends to diffuse the vorticity in the cavity shear layer and thus the location of the maximum vorticity is more affected as compared to the “shaped cylinder” control. The fact that the “shaped cylinder” is capable of suppressing the cavity resonance, despite the vortex shedding and the high frequency forcing being suppressed, is of high interest from fundamental and applied points of view.

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Khan, Ambareen, Parvathy Rajendran, and Junior Sarjit Singh Sidhu. "Passive Control of Base Pressure: A Review." Applied Sciences 11, no. 3 (February 2, 2021): 1334. http://dx.doi.org/10.3390/app11031334.

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In the present world, passive control finds application in various areas like flow over blunt projectiles, missiles, supersonic parallel diffusers (for cruise correction), the engine of jets, static testbeds of rockets, the ports of internal combustion engines, vernier rockets, and single expansion ramp nozzle (SERN) rockets. In this review, various passive control techniques to control the base pressure and regulate the drag force are discussed. In the study, papers ranging from subsonic, sonic, and supersonic flow are discussed. Different types of passive control management techniques like cavity, ribs, dimple, static cylinder, spikes, etc., are discussed in this review article. This study found that the passive control device can control the base pressure, resulting in an enhancement in the base pressure and reducing the base drag. Also, passive control is very efficient whenever there is a favorable pressure gradient at the nozzle exit.

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Ponomaryov, G. A., K. P. Levenfish, and A. E. Petrov. "Jet and counter-jet in transonic pulsar wind nebulae." Journal of Physics: Conference Series 2103, no. 1 (November 1, 2021): 012021. http://dx.doi.org/10.1088/1742-6596/2103/1/012021.

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Abstract X-ray observations show that a jet and a counter-jet in pulsar wind nebulae often differ one from another. Sometimes one of the jets is not observed at all. We show that the most likely reason for this difference is the relative motion of a pulsar and an ambient matter. Even the slow (subsonic or transonic) ambient matter stream in the pulsar rest frame strongly affects the jets, making the windward jet bright and dynamic, and the leeward jet dim and diffuse. The effect is illustrated using a relativistic MHD model of a double-torus pulsar wind nebula. The model is shown to explain reasonably well the observational appearance of the jets in the Vela nebula - a double-torus object which evolves in a transonic stream initiated by the passage of the reverse shock of the parent supernova.

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Wang, Wei, Wuli Chu, and Haoguang Zhang. "Mechanism study of performance enhancement in a subsonic axial flow compressor with recirculating casing treatment." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 4 (January 11, 2017): 680–93. http://dx.doi.org/10.1177/0954410016687140.

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The improvements in both compressor efficiency and stability have been observed in a subsonic axial flow compressor with recirculating casing treatment. The study aims to understand the underlying flow mechanisms of the beneficial effect on the compressor efficiency of recirculating casing treatment. The recirculating casing treatment was investigated experimentally and numerically. In the experiment, static pressure fluctuations over the rotor tip were measured with fast-response pressure transducers. Whole-passage time-accurate simulations were also implemented to help in understanding the flow details. The unsteadiness of double-leakage flow and its effect on the loss generated at the rotor tip were discussed in detail for the solid casing. The effect of recirculating casing treatment on the double-leakage flow related loss was subsequently investigated. The results indicate that the double leakage flow is a main loss source in the rotor tip region. The double-leakage flow is completely unsteady, which induces a cyclical fluctuation of the amount of loss generated in the rotor tip region for the solid casing. With the recirculating casing treatment installed, the high-energy jet created in recirculating loops changes the unsteady characteristics of double-leakage flow by getting it diffused over the rotor tip gap along the chordwise direction, which results in the loss fluctuation that is dominated by the high-energy jet rather than the unsteadiness of double-leakage flow. The double-leakage flow is also pushed downstream by the jet and the amount is reduced when it passes through the recirculating loops. The effect of recirculating casing treatment on the double-leakage flow is primarily responsible for the improvement in the compressor efficiency.

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Chen, Wen Hua, Qi Song, and Meng Li. "Resist Liquefaction of Subsoil of Metro and Improvement of Segments of Shield Tunneling." Advanced Materials Research 588-589 (November 2012): 1979–82. http://dx.doi.org/10.4028/www.scientific.net/amr.588-589.1979.

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Nanjing’s metro is studied as a example to introduce resist liquefaction method in this paper. Dynamic diffuse theory of structure is supposed to evaluate the width and depth of foundation treatment to resist the seismic liquefaction to think of metro structure, liquefied soil layers and different liquefaction-index. High pressure jet grouting method is researched as shield machine construction through foundations of buildings or ancient wall. An improved segments of shield tunneling method is suggest to ensure the resist liquefaction method to success.

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Journal articles on the topic 'Subsonic diffuser'

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