scholarly journals An Approach for the Development of an Aerodynamic-Structural Interaction Numerical Simulation for Aeropropulsion Systems

1996 ◽  
Author(s):  
Javaid Naziar ◽  
Rich Couch ◽  
Milt Davis
Keyword(s):  
Euler Equations ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Three Dimensional ◽  
Rotating Stall ◽  
Turbine Engine ◽  
Structural Interaction ◽  
Integrated Simulation ◽  
Interaction Simulation ◽  
Development Center

Traditionally, aeropropulsion structural performance and aerodynamic performance have been designed separately and later mated together via flight testing. In today’s atmosphere of declining resources, it is imperative that more productive ways of designing and verifying aeropropulsion performance and structural interaction be made available to the aerospace industry. One method of obtaining a more productive design and evaluation capability is through the use of numerical simulations. Currently, Lawrence Livermore National Laboratory has developed a generalized fluid/structural interaction code known as ALE3D. This code is capable of characterizing fluid and structural interaction for components such as the combustor, fan/stators, inlet and/or nozzles. This code solves the 3D Euler equations and has been applied to several aeropropulsion applications such as a supersonic inlet and a combustor rupture simulation. To characterize aerodynamic-structural interaction for rotating components such as the compressor, appropriate turbomachinery simulations would need to be implemented within the ALE3D structure. The Arnold Engineering Development Center is currently developing a three-dimensional compression system code known as TEACC (Turbine Engine Analysis Compressor Code). TEACC also solves the 3D Euler equations and is intended to simulate dynamic behavior such as inlet distortion, surge or rotating stall. The technology being developed within the TEACC effort provides the necessary turbomachinery simulation for implementation into ALE3D. This paper describes a methodology to combine three-dimensional aerodynamic turbomachinery technology into the existing aerodynamic-structural interaction simulation, ALE3D to obtain the desired aerodynamic and structural integrated simulation for an aeropropulsion system.

scholarly journals Experiments and Simulations on the Turbulent, Rarefaction Wave Driven Rayleigh–Taylor Instability

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
R. V. Morgan ◽  
J. W. Jacobs
Keyword(s):  
Rarefaction Wave ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Mixing Layer ◽  
Three Dimensional ◽  
Quantitative Agreement ◽  
Diffuse Interface ◽  
Diffusion Layer Thickness ◽  
Average Value ◽  
Rayleigh Taylor Instability

Abstract Experiments were performed to observe the growth of the turbulent, Rayleigh–Taylor unstable mixing layer generated between air and SF6, with an Atwood number of A=(ρ2−ρ1)/(ρ2+ρ1)=0.64, where ρ1 and ρ2 are the densities of air and SF6, respectively. A nonconstant acceleration with an average value of 2300g0, where g0 is the acceleration due to gravity, was generated by interaction of the interface between the two gases with a rarefaction wave. Three-dimensional, multimode perturbations were generated on the diffuse interface, with a diffusion layer thickness of δ=3.6 mm, using a membraneless vertical oscillation technique, and 20 experiments were performed to establish a statistical ensemble. The average perturbation from this ensemble was extracted and used as input for a numerical simulation using the Lawrence Livermore National Laboratory (LLNL) Miranda code. Good qualitative agreement between the experiment and simulation was observed, while quantitative agreement was best at early to intermediate times. Several methods were used to extract the turbulent growth constant α from experiments and simulations while accounting for time varying acceleration. Experimental, average bubble and spike asymptotic self-similar growth rate values range from α=0.022 to α=0.032 depending on the method used, and accounting for variable acceleration. Values found from the simulations range from α=0.024 to α=0.041. Values of α measured in the experiments are lower than what are typically measured in the literature but are more in line with those found in recent simulations.

Development of Arl’s Multi-Energy Flash Computed Tomography Diagnostic: Capability to Track Mass-Flux Through a Reconstruction Volume

2019 ◽  
Author(s):  
Michael B. Zellner ◽  
Melissa S. Love ◽  
Kyle Champley
Keyword(s):  
Computed Tomography ◽  
High Speed ◽  
Lawrence Livermore National Laboratory ◽  
National Laboratory ◽  
Three Dimensional ◽  
Flow Models ◽  
Tomography System ◽  
Spatial Dimensions ◽  
Impact Phenomena ◽  
X Ray Computed

Abstract The U.S. Combat Capabilities Development Command Army Research Laboratory and Lawrence Livermore National Laboratory are currently developing a Multi-Energy Flash Computed Tomography (MEFCT) diagnostic for multi-frame, in situ, three-dimensional radiographic assessment of ballistic impact phenomena. To accomplish this, we combine the capabilities of medical X-ray computed tomography and high-speed computed tomography, to produce a system that captures three independent, time-sequenced volume reconstructions throughout the timespan of a typical dynamic ballistic event. Because this system has the capability to image an event across three spatial dimensions and time, it is the first of its kind to track mass/material-flux of an un-bounded system through a volume at ballistic timescales. To demonstrate the diagnostic’s capabilities, an assessment of a bullet penetrating an aluminum plate is performed. A compilation of the three volume reconstructions were computed to describe the event. The results were compared to a state-of-the-art simulation of the event using EPIC, a Lagrangian hydrocode with penetration applications. This comparison shows how using a four-dimensional computed tomography system can benefit the validation of physical failure and mass/material-flow models.

3D Unsteady Computation of Stall Inception in Axial Compressors

2010 ◽  
Author(s):  
Baofeng Tu ◽  
Jun Hu ◽  
Yong Zhao
Keyword(s):  
Numerical Simulation ◽  
Euler Equations ◽  
Three Dimensional ◽  
Rotating Stall ◽  
Computational Domain ◽  
Stall Inception ◽  
Axial Compressors ◽  
Stall Cells ◽  
Unsteady Numerical Simulation ◽  
Aero Engines

Rotating stall is one of the unsteady phenomena in multistage axial compressors that will damage both of performance and service life of aero engines. Stall inception is a dynamic process including appearance of pre-stall disturbance, evolvement of disturbances into stall cells, and development of stall cells. The main purpose in researching stall inception is to reveal the origins of disturbances and stall cells, investigate the effects of aerodynamic design variations on stall inception, and find the effective ways to prevent engines from turning into rotating stall or surge. Numerical simulation is an economic, reliable and rapid tool to study stall inception. As stall inception is three-dimensional and unsteady, numerical simulation should be capable of describing these aspects. In this paper, a three dimensional unsteady computational model based on the three-dimensional unsteady Euler equations and the three dimensional multi actuator-disks model has been developed. The computational domain can be divided into two kinds. One is blade-free regions, which consist of upstream duct, the axial gaps among blade rows, and downstream duct. The other one is blade rows. The flows in blade-free regions considered inviscid, unsteady, and can be resolved using three-dimensional unsteady Euler equations. The blade rows are replaced by multi actuator-disks with different total-to-static characteristics. By added the correlation functions of inlet and outlet flow angles, we can compute the flow field by combining the Euler equations and the multi actuator-disks model. A two-stage low-speed compressor in NUAA has been investigated, and the predicted results indicates that the second stage comes out stall cell first, and the full developed stall cell rotates at about 40.4% rotor speed, which coincides with the experimental data.

A three-dimensional compressible flow model for rotating waves in vaneless diffusers with unparallel walls

2012 ◽  
Vol 226 (9) ◽  
pp. 2230-2249 ◽  
Author(s):  
Feng Sheng ◽  
Hua Chen ◽  
Xiao-cheng Zhu ◽  
Zhao-hui Du
Keyword(s):  
Compressible Flow ◽  
Euler Equations ◽  
Flow Model ◽  
Three Dimensional ◽  
Rotating Stall ◽  
Experimental Result ◽  
Viscous Effects ◽  
Rotating Waves ◽  
Vaneless Diffusers ◽  
Suppression Effects

A three-dimensional compressible flow model is presented to study the occurrence of weak rotating waves in unparallel wall vaneless diffusers in centrifugal compressors. The model extends the three-dimensional compressible flow model for parallel wall diffusers recently developed by present authors. Linearised three-dimensional compressible Euler equations casted on a rotating frame of reference travelling at the same speeds as the waves are employed and the viscous effects are ignored. Complex functions of the solutions to the linearised Euler equations are then obtained by a second-order finite difference method and the singular value decomposition technique. Undisturbed flow is assumed potential and first solved by numerical method of strongly implicit procedure. Critical inlet flow rate and rotating wave speed of diffusers of three different shroud wall shapes, namely, convergent, convergent then divergent and constant area tapered, are studied for three different diffuser outlet-to-inlet radius ratios and for different inlet Mach numbers, and results compared with those from diffusers with parallel walls. The results show suppression effects on rotating stall by the contracting walls and the suppression effects vary with wall contraction rate, wall shape, inlet Mach number and the diffuser radius ratio. Further, the effects of diffuser inlet contraction are studied and prediction of the model is compared with experimental result.

Sign in / Sign up

Export Citation Format

Share Document