Two-Dimensional Collision Simulations of Low-Speed Crash Tests

2013 ◽  
Author(s):  
Eric Deyerl ◽  
Louis Cheng ◽  
Jordan Gatti
Keyword(s):  
Two Dimensional ◽  
Low Speed ◽  
Crash Tests

Mixing in Axial Flow Compressors: Part I — Test Facilities and Measurements in a Four-Stage Compressor

1990 ◽  
Author(s):  
Y. S. Li ◽  
N. A. Cumpsty
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Two Dimensional ◽  
Similar Magnitude ◽  
Low Speed ◽  
The Third ◽  
Mixing Coefficients ◽  
Experimental Facilities ◽  
Axial Flow Compressors

The mechanism of mixing in axial flow compressors has been investigated in two low speed machines. For reasons of length this is described in two parts. Results in a 4-stage compressor are described here in Part I and show that the mixing coefficients across the first and the third stators are of similar magnitude. Part I also describes the background and experimental facilities and techniques used in both parts together with the nomenclature and all the references. Part II describes the results from a large single stage compressor. It also presents measurements of mixing in a simple two-dimensional duct, and presents conclusions for the whole investigation.

A Study of Spike and Modal Stall Phenomena in a Low-Speed Axial Compressor

1997 ◽  
Author(s):  
T. R. Camp ◽  
I. J. Day
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Stability Criteria ◽  
Stall Inception ◽  
Low Speed ◽  
The Stability ◽  
Dimensional Instability

This paper presents a study of stall inception mechanisms a in low-speed axial compressor. Previous work has identified two common flow breakdown sequences, the first associated with a short lengthscale disturbance known as a ‘spike’, and the second with a longer lengthscale disturbance known as a ‘modal oscillation’. In this paper the physical differences between these two mechanisms are illustrated with detailed measurements. Experimental results are also presented which relate the occurrence of the two stalling mechanisms to the operating conditions of the compressor. It is shown that the stability criteria for the two disturbances are different: long lengthscale disturbances are related to a two-dimensional instability of the whole compression system, while short lengthscale disturbances indicate a three-dimensional breakdown of the flow-field associated with high rotor incidence angles. Based on the experimental measurements, a simple model is proposed which explains the type of stall inception pattern observed in a particular compressor. Measurements from a single stage low-speed compressor and from a multistage high-speed compressor are presented in support of the model.

Maximizing 3D Clocking Effect by the Guidance of Edge Matching

2007 ◽  
Author(s):  
LuCheng Ji ◽  
Jiang Chen ◽  
Zhao Yan ◽  
WeiLin Yi
Keyword(s):  
Three Dimensional ◽  
Two Dimensional ◽  
Computational Resource ◽  
Axial Turbine ◽  
Low Speed ◽  
Edge Matching ◽  
Simplified Method ◽  
Resource Requirements

Clocking can produce benefit has become a common viewpoint in turbomachinery field. However, there still is a question, that is “why the benefit of two-dimensional (2D) clocking model is always larger than that of three-dimensional (3D) clocking model?”. A general way of maximizing 3D clocking benefit by edge matching (EM) is put forward. On the basis of experience and knowledge accumulated in investigations on clocking effects, a further simplified method is presented and emphasized. Aachen 1.5 stage low speed subsonic axial turbine is used as an example of maximizing 3D clocking benefits by applying EM. Results show that 3D clocking benefit can be maximized by routinely using EM with relatively low computational resource requirements, and the benefit is considerable enough to be paid more attention.

Mixing in Axial Flow Compressors: Part I—Test Facilities and Measurements in a Four-Stage Compressor

1991 ◽  
Vol 113 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Y. S. Li ◽  
N. A. Cumpsty
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Two Dimensional ◽  
Similar Magnitude ◽  
Low Speed ◽  
The Third ◽  
Mixing Coefficients ◽  
Experimental Facilities ◽  
Axial Flow Compressors

The mechanism of mixing in axial flow compressors has been investigated in two low-speed machines. For reasons of length this is described in two parts. Results in a four-stage compressor are described here in Part I and show that the mixing coefficients across the first and the third stators are of similar magnitude. Part I also describes the background and experimental facilities and techniques used in both parts together with the nomenclature and all the references. Part II describes the results from a large single-stage compressor. It also presents measurements of mixing in a simple two-dimensional duct, and presents conclusions for the whole investigation.

scholarly journals A CFD-Compatible Amplification Factor Transport Equation for Oblique Tollmien-Schlichting Waves in Supersonic Boundary Layers

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
JiaKuan Xu ◽  
Lei Qiao ◽  
Junqiang Bai
Keyword(s):  
Transport Equation ◽  
Amplification Factor ◽  
Flow Instability ◽  
Supersonic Flows ◽  
Boundary Layer Transition ◽  
Linear Stability Theory ◽  
Two Dimensional ◽  
Layer Transition ◽  
Low Speed ◽  
Tollmien Schlichting

Boundary layer transition is a hot research topic in fluid mechanics and aerospace engineering. In low-speed flows, two-dimensional Tollmien-Schlichting (T-S) waves always dominate the flow instability, which has been modeled by Coder and Maughmer from 2013. However, in supersonic flows, three-dimensional oblique Tollmien-Schlichting waves become dominant in flow instability. Inspired by Coder and Maughmer’s NTS amplification factor transport equation for two-dimensional Tollmien-Schlichting waves in low-speed flows and Kroo and Sturdza’s linear stability theory (LST) analysis results for oblique Tollmien-Schlichting waves in supersonic flows, a new amplification factor transport equation for oblique Tollmien-Schlichting waves has been developed based on LST. The compressible Falkner-Skan similarity equations are introduced to build the relationships between nonlocal variables and local variables so that all the variables used in the present model can be calculated using local variables. Applications of this new transport equation to the flows over supersonic flat plate, 3% thick biconvex airfoil, and one modified supersonic laminar airfoil show promising results compared with the standard LST analysis results.

Research on Computational Fluid Dynamics with Effect of Grid Quality on the Accuracy of Simulated Results of Two Dimensional Low-Speed Parallel Flow

2014 ◽  
Vol 685 ◽  
pp. 232-235
Author(s):  
Ning Kang ◽  
Yuan Cao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Direction ◽  
Grid Generation ◽  
Domain Size ◽  
Parallel Flow ◽  
Computational Error ◽  
Two Dimensional ◽  
Low Speed ◽  
Generation Costs

In the field of computational fluid dynamics, grid generation costs most of work. The accuracy and reliability of the simulated results depend directly on grid quality. The two dimensional parallel flow with low speed was used to study the effect of grid quality on simulated results. Several conclusions are obtained. The computational error decreases with the increase of domain size in flow direction. Too many grids in flow direction will lead to bigger round-off error, while too few grids will make it harder to catch the correct flow. The increase of grid quantity in the direction perpendicular to flow direction will decrease the computational error, but the effect is not obvious. Increasing the grid quantity in the area near the wall will decrease the computational error.

scholarly journals Physics of Airfoil Clocking in Axial Compressors

1997 ◽  
Author(s):  
Karen L. Gundy-Burlet ◽  
Daniel J. Dorney
Keyword(s):  
Unsteady Flow ◽  
Thin Layer ◽  
Relative Motion ◽  
Unsteady Aerodynamics ◽  
Flow Fields ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Low Speed ◽  
Axial Compressors ◽  
Potential Interactions

Axial compressors have inherently unsteady flow fields because of relative motion between rotor and statnr airfnils. This relative motion leads to viscous and inviscid (potential) interactions between blade rows. As the number of stages increases in a turbomachine, the buildup of convected wakes can lead in progressively more complex wake/wake and wake/airfnil interactions. Variations in the relative circumferential positions of stators or rotors can change these interactions, leading to different unsteady forcing functions on airfoils and different compressor efficiencies. The current study uses an unsteady, two-dimensional thin-layer Navier-Stokes zonal approach to investigate the unsteady aerodynamics of stator clocking in a low-speed 2 ½-stage compressor. Relative motion between rotors and stators is made possible by the use of systems of patched and overlaid grids. Results include surface pressures instantaneous forces and efficiencies for a 2 ½-stage compressor configuration.

scholarly journals Whiplash Injury Case Studies through Low Speed Rear-end Crash Tests

2016 ◽  
Vol 24 (4) ◽  
pp. 432-438 ◽  
Author(s):  
Namkyoung Lim ◽  
Sangwoo Shim ◽  
Hyuncheol Jung
Keyword(s):  
Case Studies ◽  
Whiplash Injury ◽  
Low Speed ◽  
Crash Tests
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