A set of new general unified fluid dynamic equations for arbitrary equation of state

2008 ◽  
Vol 222 (6) ◽  
pp. 955-958 ◽  
Author(s):  
D G Huang ◽  
H Y Ke ◽  
J Y Du
Keyword(s):  
Fluid Dynamics ◽  
Equation Of State ◽  
Flow Field ◽  
Internal Energy ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Computational Method ◽  
Dynamic Equations ◽  
Pressure Correction ◽  
Key Factor

In flow field, the pressure, which usually drives the fluid to flow, is one of the most important variables. However, in the conventional computational method, density, velocity, and temperature or stagnation internal energy are usually used as basic unknown variables, as well as the pressure, a key factor for fluid dynamics, is usually solved indirectly by pressure correction or applying the equation of state. By rational mathematical deduction, a set of new general unified equations for fluid dynamics are deduced in this paper. In these equations, the static pressure and static enthalpy are adopted as basic unknown variables.

Investigation of the Flow Field on a Transonic Turbine Nozzle Guide Vane With Rim Seal Cavity Flow Ejection

2009 ◽  
Author(s):  
M. Pau ◽  
G. Paniagua
Keyword(s):  
Flow Field ◽  
Static Pressure ◽  
Numerical Study ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cavity Flow ◽  
Trailing Edge ◽  
Dynamic Simulations ◽  
Purge Flow

Ensuring an adequate life of high pressure turbines requires efficient cooling methods, such as rim seal flow ejection from the stator-rotor wheel space cavity interface, which prevents hot gas ingress into the rotor disk. The present work addresses the potential to improve the efficiency in transonic turbines at certain rim seal ejection rates. To understand this process a numerical study was carried out combining computational fluid dynamic simulations (CFD) and experiments on a single stage axial test turbine. The three dimensional steady CFD analysis was performed modeling the purge cavity flow ejected downstream of the stator blade row, at three flow regimes, subsonic M2 = 0.73, transonic M2 = 1.12 and supersonic M2 = 1.33. Experimental static pressure measurements were used to calibrate the computational model. The main flow field-purge flow interaction is found to be governed by the vane shock structures at the stator hub. The interaction between the vane shocks at the hub and the purge flow has been studied and quantitatively characterized as function of the purge ejection rate. The ejection of 1% of the core flow from the rim seal cavity leads to an increase of the hub static pressure of approximately 7% at the vane trailing edge. This local reduction of the stator exit Mach number decreases the trailing edge losses in the transonic regime. Finally, a numerically predicted loss breakdown is presented, focusing on the relative importance of the trailing edge losses, boundary layer losses, shock losses and mixing losses, as a function of the purge rate ejected. Contrary to the experience in subsonic turbines, results in a transonic model demonstrate that ejecting purge flow improves the vane efficiency due to the shock structures modification downstream of the stator.

Flow Field and Static Pressure Analysis of Adsorption Principle of Wall-Climbing Robot

2013 ◽  
Vol 427-429 ◽  
pp. 65-68
Author(s):  
Yi Tong Ma ◽  
Fang Xing Li ◽  
Xue Shan Gao ◽  
Wei Jie Bo
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Surface Flow ◽  
Air Inlet ◽  
High Speed Rotation ◽  
Basic Parameters ◽  
Speed Rotation ◽  
Pressure Analysis

The impeller is key element that brings about negative pressure adsorption. The efficiency of the impeller will determine the adsorption capacity of robot. In this paper, physical model is built based on the theory of fluid dynamics by taking a common high speed rotation of impeller as a research object. The basic parameters and boundary conditions are set and a 3D fluid dynamic simulation is done based on FloEFD. The factors such as blade curve, rotational speed and air inlet velocity which have effect on surface flow field impeller are investigated. Then the results are shown by figures and the study analysis is carried on.

Research of 3D-CFD Simulation on a Large Sized Pit Type Carburizing Furnace

2006 ◽  
Vol 118 ◽  
pp. 337-342
Author(s):  
Wei Min Zhang ◽  
Ye Ma ◽  
Lin Lin Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Cfd Simulations ◽  
3 Dimensional ◽  
Set Up ◽  
Carburizing Process

A fluid dynamic model was set up to describe the flow field of gas in a large sized pit type carburizing furnace when large sized gears were being carburized. The commercial software Fluent was adopted to carry out 3 dimensional computational fluid dynamics (3D-CFD) simulations of the gas flow field under different, actually four kinds of , furnace designs in this article. The flow fields of the carburizing gas around the part were analyzed. According to the simulations and analysis, it was shown that the number of fans on gear’s carburizing is not a primary factor, using a air inducting tub can improve the carburizing process significantly and proper loading tray design can also be positive. The results indicate that the simulation provides a reference to the furnace’s design optimization.

The Hydraulic Characteristics of Inner Loop Biological Fluidized Bed Set Ring-Type Baffle

2013 ◽  
Vol 807-809 ◽  
pp. 1147-1150
Author(s):  
Zhan Xiu Chen ◽  
Juan Men
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Fluidized Bed ◽  
Turbulence Intensity ◽  
Static Pressure ◽  
Fluidized Bed Reactor ◽  
Hydraulic Characteristics ◽  
Ring Type ◽  
Static Pressure Difference

The flow field of the traditional inner loop biological fluidized bed reactor (ILBFBR) and a new biological fluidized bed reactor set ring-type baffle was calculated by computational fluid dynamics. The results show that the gas holdup of drop zone in ILBFBR set the ring-type baffle can increase significantly, the flow rate of drop zone in ILBFBR with the ring-type baffle is faster than that in traditional ILBFBR, and turbulence intensity distributed more evenly all in rising zone and drop zone in ILBFBR set the ring-type baffle than that in traditional ILBFBR, but static pressure difference of ILBFBR set ring-type baffle is higher than that of the traditional ILBFBR.

scholarly journals Research on dynamic characteristics of gas film of spherical hybrid gas bearings based on computational fluid dynamics

2020 ◽  
Vol 44 (1) ◽  
pp. 23-37
Author(s):  
Chenhui Jia ◽  
Zhiwu Cui ◽  
Shijun Guo ◽  
Wensuo Ma
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Bearing Capacity ◽  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Gas Flow ◽  
Static Pressure ◽  
Gas Bearings ◽  
Gas Bearing

A realizable k–ε turbulence model for spherical spiral groove hybrid gas bearing films was established based on computational fluid dynamics (CFD). A six degrees of freedom passive grid was used to calculate the gas film pressure distribution, bearing capacity, and dynamic characteristic coefficients numerically. The gas flow field dynamic and static pressure coupling mechanism was studied. The effects of the rotation speed, gas film thickness eccentricity ratio, and gas supply pressure on the dynamic and static pressure bearing capacity, and dynamic characteristic coefficients during operation were analyzed as a method of research into the mechanical mechanisms of gas bearing stability. The CFD calculation analysis can simulate the complex gas flow in the transient flow field of the gas film and determine reasonable operation parameters to optimize the dynamic and static pressure coupling effects, which can improve the gas film bearing capacity, dynamic characteristics, and operational stability of gas bearings.

Numerical Analysis of an External Flow-Field around a Formula SAE Car Body Based on FLUENT

2014 ◽  
Vol 1039 ◽  
pp. 17-24 ◽  
Author(s):  
Xiao Han Cheng ◽  
Shan Ming Luo ◽  
Xue Feng Chang ◽  
Dan Xie
Keyword(s):  
Flow Field ◽  
Drag Coefficient ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Aerodynamic Characteristics ◽  
External Flow ◽  
Attack Angle ◽  
The Body ◽  
Formula Sae ◽  
Rear Wing

This paper proposed a method to analysis an external flow-field around a Formula SAE car. Firstly, the body of Formula SAE car was designed conforming to the FSAE rules using CATIA. Then, the model of the external flow-field around the vehicle was established using computational fluid dynamic technology. A comparative analysis of the aerodynamic characteristics was made for the body between the conditions of being without the wing package and being with the wing package under different attack angle to get the static pressure graph, the lift force and the drag force then worked out the drag coefficient and confirmed which is the most suitable angle for the wings. The results showed that: the static pressure of the front body, the front part of the tires and the driver’s chest and head is the highest; the body has good streamline since its drag coefficient is 0.385; the rear wings can supply 65% downforce, when the attack angle of the rear wing is set to 8°. Finally, the real mold was fabricated according to the above 3D model and the analysis results. The method presented in this paper can provide theoretical basis and technical parameter for the aerodynamic formation designing and amelioration of the Formula SAE cars. Also it has guiding significance for the design and aerodynamic analysis of the Ordinary Passenger car.

Computational Fluid Dynamics Applied to Three-Dimensional Nonreacting Inviscid Flows in an Internal Combustion Engine

1979 ◽  
Vol 101 (3) ◽  
pp. 367-372 ◽  
Author(s):  
M. D. Griffin ◽  
J. D. Anderson ◽  
E. Jones
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Internal Combustion ◽  
Computational Method ◽  
Striking Similarity ◽  
Stroke Cycle

The three-dimensional inviscid flowfield between the face of the piston and the top of the cylinder in a reciprocating internal combustion engine is calculated for a complete four-stroke cycle (intake, compression, power, exhaust). The fluid dynamic aspects are emphasized; combustion is simply modeled by constant-volume heat addition. The computational method is an explicit time-dependent finite-difference solution of the governing fluid dynamic equations. The results show that a well-defined three-dimensional swirling flow pattern is established during the intake stroke, and that this swirl persists throughout the complete four-stroke cycle. Such a flowfield will have direct influence on I.C. engine combustion phenomena. Moreover, the radial distributions of pressure and temperature show a nearly-axisymmetric behavior, while the three-dimensional results in the valve plane show a striking similarity to previous two-dimensional results. The present investigation is the first three-dimensional calculation of the flowfield for all four strokes, and has important implications for future work in the application of computational fluid dynamics to I. C. engine analysis.

Investigation of the Flow Field on a Transonic Turbine Nozzle Guide Vane With Rim Seal Cavity Flow Ejection

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
M. Pau ◽  
G. Paniagua
Keyword(s):  
Flow Field ◽  
Static Pressure ◽  
Numerical Study ◽  
Guide Vane ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Cavity Flow ◽  
Trailing Edge ◽  
Purge Flow ◽  
Exit Mach Number

Ensuring an adequate life of high pressure turbines requires efficient cooling methods such as rim seal flow ejection from the stator-rotor wheel space cavity interface, which prevents hot gas ingress into the rotor disk. The present paper addresses the potential to improve the efficiency in transonic turbines at certain rim seal ejection rates. To understand this process, a numerical study was carried out, combining computational fluid dynamic (CFD) simulations and experiments on a single stage axial test turbine. The three dimensional steady CFD analysis was performed, modeling the purge cavity flow ejected downstream of the stator blade row at three flow regimes: subsonic M2=0.73, transonic M2=1.12, and supersonic M2=1.33. Experimental static pressure measurements were used to calibrate the computational model. The main flow field-purge flow interaction is found to be governed by the vane shock structures at the stator hub. The interaction between the vane shocks at the hub and the purge flow has been studied and quantitatively characterized as a function of the purge ejection rate. The ejection of 1% of the core flow from the rim seal cavity leads to an increase in the hub static pressure of approximately 7% at the vane trailing edge. This local reduction of the stator exit Mach number decreases the trailing edge losses in the transonic regime. Finally, a numerically predicted loss breakdown is presented, focusing on the relative importance of the trailing edge losses, boundary layer losses, shock losses, and mixing losses, as a function of the purge rate ejected. Contrary to the experience in subsonic turbines, results in a transonic model demonstrate that ejecting purge flow improves the vane efficiency due to the shock structure modification downstream of the stator.

Pressure variation in a fluid at rest (hydrostatics)

2018 ◽  
Author(s):  
Marcel Escudier
Keyword(s):  
Equation Of State ◽  
Static Pressure ◽  
Applied Pressure ◽  
Pressure Variation ◽  
Constant Density ◽  
Fluid Temperature ◽  
Earth’S Atmosphere ◽  
Hydrostatic Equation ◽  
Depth Increase ◽  
Pressure Changes

The three fundamental principles for the variation of static pressure p throughout a body of fluid at rest are (a) the pressure at a point is the same in all directions (Pascal’s law), (b) the pressure is the same at all points on the same horizontal level, and (c) the pressure increases with depth z according to the hydrostatic equation. dp/dz= ρ‎g For a fluid with constant density ρ‎, the increase in pressure over a depth increase h is ρ‎gh, a result which can be used to analyse the response of simple barometers and manometers to applied pressure changes and differences. In situations where very large changes in pressure occur an equation of state may be required to relate pressure and density together with an assumption about the fluid temperature. The hydrostatic equation is still valid but more difficult to integrate, as illustrated by consideration of the earth’s atmosphere.

scholarly journals Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Junfeng Sun ◽  
Meihong Liu ◽  
Zhen Xu ◽  
Taohong Liao ◽  
Xiangping Hu ◽  
...  
Keyword(s):  
Flow Field ◽  
Film Thickness ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Equivalent Stress ◽  
Three Dimensional ◽  
High Rotational Speed ◽  
Flexible Support ◽  
Flow Field Characteristics

A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.

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