Notes on the boundary conditions for fluid-dynamic equations on the interface of a gas and its condensed phase

2001 ◽  
Vol 13 (1) ◽  
pp. 324-334 ◽  
Author(s):  
Yoshio Sone ◽  
Shigeru Takata ◽  
François Golse
Keyword(s):  
Boundary Conditions ◽  
Condensed Phase ◽  
Fluid Dynamic ◽  
Dynamic Equations

NPSS Volume Dynamic Capability for Real-Time Physics Based Engine Modeling

2011 ◽  
Author(s):  
Christopher Argote ◽  
Brian K. Kestner ◽  
Dimitri N. Mavris
Keyword(s):  
Boundary Conditions ◽  
Real Time ◽  
Fluid Dynamic ◽  
Critical Time ◽  
Momentum Conservation ◽  
Drop Out ◽  
Dynamic Equations ◽  
High Fidelity ◽  
Time Step ◽  
Engine Cycle

This paper introduces a new capability and method for solving transient engine cycles for the potential application of real-time simulation in the cycle analysis code Numerical Propulsion System Simulation (NPSS). This method utilizes a new element which models volume dynamics, a set of equations that characterize the unsteady behavior of fluid dynamic and thermodynamic properties with respect to a volume and boundary conditions. These equations are derived from the Euler equations for conservation of mass, momentum, and energy. Physics based real-time engine models often consider the effects of volume dynamics; however it is normal to see the momentum conservation drop out. This is largely due to the high frequency response of momentum which yields smaller time steps thus increasing the cost associated with computation time. The new high fidelity volume dynamics element is introduced with all three conservations laws working together. NPSS’s interpreted language provides the flexibility to allow the volume dynamics to be solved explicitly, however by rearranging the momentum equation, it can be solved implicitly therefore increasing the critical time step. In addition to improving transient modeling fidelity, the new volume dynamics element can be used to drive the cycle. Rather than balancing error terms in a Newton-Raphson solver, the volume dynamic equations provide the necessary communication between the engine cycle and boundary conditions. These equations alone can drive the engine model towards a steady state solution. Using a basic forward Euler numerical integration technique to solve the volume dynamic equations the engine cycle only requires a single pass per time step. This document illustrates the development of both the new element and the methodology in cycle modeling using the volume dynamics. Two example models are created and analyzed in this paper, first, a simple inlet, duct, nozzle system is analyzed. Second, a separate flow long duct turbojet is examined. These two models are used to demonstrate the real time capabilities of the high fidelity transient analysis, as well as highlight some of the challenges in the implementation of volume dynamics on a given cycle.

scholarly journals Fluid-dynamic equations for reacting gas mixtures

2005 ◽  
Vol 50 (1) ◽  
pp. 43-62 ◽  
Author(s):  
Marzia Bisi ◽  
Maria Groppi ◽  
Giampiero Spiga
Keyword(s):  
Fluid Dynamic ◽  
Gas Mixtures ◽  
Dynamic Equations

scholarly journals Multi-Fidelity Simulation of a Turbofan Engine With Results Zoomed Into Mini-Maps for a Zero-D Cycle Simulation

2004 ◽  
Author(s):  
Mark G. Turner ◽  
John A. Reed ◽  
Robert Ryder ◽  
Joseph P. Veres
Keyword(s):  
Boundary Conditions ◽  
Fluid Dynamic ◽  
Thermodynamic Cycle ◽  
High Fidelity ◽  
Operating Characteristics ◽  
Cycle Model ◽  
Turbofan Engine ◽  
Engine Model ◽  
Cycle Simulation ◽  
Component Models

A Zero-D cycle simulation of the GE90-94B high bypass turbofan engine has been achieved utilizing mini-maps generated from a high-fidelity simulation. The simulation utilizes the Numerical Propulsion System Simulation (NPSS) thermodynamic cycle modeling system coupled to a high-fidelity full-engine model represented by a set of coupled 3D computational fluid dynamic (CFD) component models. Boundary conditions from the balanced, steady-state cycle model are used to define component boundary conditions in the full-engine model. Operating characteristics of the 3D component models are integrated into the cycle model via partial performance maps generated from the CFD flow solutions using one-dimensional meanline turbomachinery programs. This paper high-lights the generation of the highpressure compressor, booster, and fan partial performance maps, as well as turbine maps for the high pressure and low pressure turbine. These are actually “mini-maps” in the sense that they are developed only for a narrow operating range of the component. Results are compared between actual cycle data at a take-off condition and the comparable condition utilizing these mini-maps. The mini-maps are also presented with comparison to actual component data where possible.

Research on Dynamic Simulation of AUV Launching a Towed Navigation Buoyage

2013 ◽  
Vol 433-435 ◽  
pp. 1170-1174
Author(s):  
Guang Pan ◽  
Zhi Dong Yang ◽  
Xiao Xu Du
Keyword(s):  
Angular Momentum ◽  
Boundary Conditions ◽  
Dynamic Simulation ◽  
Numerical Scheme ◽  
Mathematic Model ◽  
Dynamic Equations ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Towed Cable ◽  
Undersea Vehicle

A mathematic model was established to simulate the process of AUV (autonomous undersea vehicle) launching a towed buoyage. Based on the lumped mass method and moment theorem and angular momentum theorem, dynamic equations of the cable and the buoyage were developed, respectively. Then the boundary conditions and the numerical scheme to deal with the cable with non-fixed length were presented. Moreover, the process of AUV launching a towed cable was simulated. By using the model, the results show the trajectory of buoyage and shape of towed cable can be well predicted.

Numerical Methods of Solving Fluid Dynamic Equations

2009 ◽  
pp. 1215-1383
Author(s):  
S. Nakamura ◽  
Rainald Löhner ◽  
Evangelos Hytopoulos ◽  
Tayfun E. Tezduyar ◽  
Marek Behr ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Fluid Dynamic ◽  
Dynamic Equations

Paper 18: Fluid Dynamic Aspects of Unsteady Flow in Branched Ducts

1967 ◽  
Vol 182 (8) ◽  
pp. 167-174 ◽  
Author(s):  
B. E. L. Deckker ◽  
D. H. Male
Keyword(s):  
Boundary Conditions ◽  
Unsteady Flow ◽  
Fluid Dynamic ◽  
High Amplitude ◽  
Quantitative Information ◽  
Schlieren Method ◽  
Pressure Losses ◽  
Static Pressure Distribution ◽  
Flow Through ◽  
Hydraulic Analogy

Unsteady flow through three-branched pipe configurations has been investigated with the object of finding boundary conditions suitable for use in the analysis of high-amplitude waves using the method of characteristics. The schlieren method and the hydraulic analogy were used to obtain qualitative information about the quasi-steady flow patterns. Quantitative information concerning these patterns was obtained by the measurement of stagnation pressure losses and of the static pressure distribution. Several methods of deriving boundary conditions have been reviewed, and it is considered that those obtained directly by experiment are the most convenient to use.

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