scholarly journals Microramp Flow Control for Oblique Shock Interactions: Comparisons of Computational and Experimental Data

2010 ◽  
Author(s):  
Stefanie Hirt ◽  
David Reich ◽  
Michael O'Connor
Keyword(s):  
Experimental Data ◽  
Flow Control ◽  
Oblique Shock ◽  
Shock Interactions

Glancing interactions between single and intersecting oblique shock waves and a turbulent boundary layer

1986 ◽  
Vol 170 ◽  
pp. 411-433 ◽  
Author(s):  
D. J. Mee ◽  
R. J. Stalker ◽  
J. L. Stollery
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Field ◽  
Superposition Principle ◽  
Three Dimensional ◽  
Oblique Shock ◽  
Shock Interactions ◽  
Expansion Waves ◽  
Shock Generator ◽  
Boundary Layer Interaction

The three-dimensional interactions of weak swept oblique shock and expansion waves and a turbulent boundary layer on a flat plate are investigated. Upstream influences in a single swept interaction are found to be consistent with a model of the flow involving shock/boundary-layer interaction characteristics. The model implies that there is more rapid thickening of the boundary layer close to the shock generator and this is seen to be consistent with surface streamline patterns. It is also found that a superposition principle, which is inherent in the triple-deck model of shock/boundary-layer interactions proposed by Lighthill, can be used to predict the pressure field and surface streamlines for the case of intersecting shock interactions and for the intersection of a shock with a weak expansion.

scholarly journals MHD Flow Control of Oblique Shock Waves Around Ramps in Low-temperature Supersonic Flows

2010 ◽  
Vol 23 (1) ◽  
pp. 22-32 ◽  
Author(s):  
Su Changbing ◽  
Li Yinghong ◽  
Cheng Bangqin ◽  
Wang Jian ◽  
Cao Jun ◽  
...  
Keyword(s):  
Low Temperature ◽  
Shock Waves ◽  
Flow Control ◽  
Mhd Flow ◽  
Supersonic Flows ◽  
Oblique Shock

scholarly journals Experimental data for a flow control valve

Data in Brief ◽  
2019 ◽  
Vol 24 ◽  
pp. 103892 ◽  
Author(s):  
P. Rezazadeh ◽  
M. Bijankhan ◽  
A. Mahdavi Mazdeh
Keyword(s):  
Experimental Data ◽  
Flow Control ◽  
Control Valve ◽  
Flow Control Valve

scholarly journals An Electro-Pneumatic Force Tracking System using Fuzzy Logic Based Volume Flow Control

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 4011 ◽  
Author(s):  
Zhonglin Lin ◽  
Qingyan Wei ◽  
Runmin Ji ◽  
Xianghua Huang ◽  
Yuan Yuan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fuzzy Logic ◽  
Flow Control ◽  
Duty Cycle ◽  
Pulse Width ◽  
Control Method ◽  
Volume Flow ◽  
Pneumatic System ◽  
Step Response ◽  
Average Error

In this paper, a fuzzy logic based volume flow control method is proposed to precisely control the force of a pneumatic actuator in an electro-pneumatic system including four on-off valves. The volume flow feature, which is the relationship between the duty cycle of the pulse width modulation (PWM) period, pressure difference, and volume flow of an on-off valve, is based on the experimental data measured by a high-precision volume flow meter. Through experimental data analysis, the maximum and minimum duty cycles are acquired. A new volume flow control method is introduced for the pneumatic system. In this method, the raw measured data are innovatively processed by a segmented, polynomial fitting method, and a newly designed procedure for calculating the duty cycle is adopted. This procedure makes it possible to combine the original data with fuzzy logic control (FLC). Additionally, the method allows us to accurately control the minimum and maximum opening pulse width of the valve. Several experiments are performed based on the experimental data, instead of the traditional theoretical models. Only 0.141 N (1.41%) overshoot and 0.03 N (0.03%) steady-state error are observed in the step response experiment, and 0.123 N average error is found while tracking the sine wave reference.

scholarly journals Experiments on Oblique Shock Interactions with Planar Mixing Regions

AIAA Journal ◽  
10.2514/2.26 ◽  
1997 ◽  
Vol 35 (11) ◽  
pp. 1774-1777 ◽  
Author(s):  
D. R. Buttsworth ◽  
R. G. Morgan ◽  
T. V. Jones
Keyword(s):  
Oblique Shock ◽  
Shock Interactions

scholarly journals Numerical Investigation of Spray Collapse in GDI with OpenFOAM

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 104
Author(s):  
Jan Wilhelm Gärtner ◽  
Ye Feng ◽  
Andreas Kronenburg ◽  
Oliver T. Stein
Keyword(s):  
Experimental Data ◽  
Direct Injection ◽  
Operating Conditions ◽  
Test Case ◽  
Direct Injection Engines ◽  
Shock Interactions ◽  
Single Hole ◽  
First Case ◽  
Collapse Behavior

During certain operating conditions in spark-ignited direct injection engines (GDI), the injected fuel will be superheated and begin to rapidly vaporize. Fast vaporization can be beneficial for fuel–oxidizer mixing and subsequent combustion, but it poses the risk of spray collapse. In this work, spray collapse is numerically investigated for a single hole and the spray G eight-hole injector of an engine combustion network (ECN). Results from a new OpenFOAM solver are first compared against results of the commercial CONVERGE software for single-hole injectors and validated. The results corroborate the perception that the superheat ratio Rp, which is typically used for the classification of flashing regimes, cannot describe spray collapse behavior. Three cases using the eight-hole spray G injector geometry are compared with experimental data. The first case is the standard G2 test case, with iso-octane as an injected fluid, which is only slightly superheated, whereas the two other cases use propane and show spray collapse behavior in the experiment. The numerical results support the assumption that the interaction of shocks due to the underexpanded vapor jet causes spray collapse. Further, the spray structures match well with experimental data, and shock interactions that provide an explanation for the observed phenomenon are discussed.

A Comparison Between Numerical and Experimental High Reynolds Number Supersonic Jets Generated by Millimeter Scale Converging-Diverging Nozzles

2020 ◽  
Author(s):  
Joseph M. Conahan ◽  
Ozan C. Ozdemir ◽  
Mohammad E. Taslim ◽  
Sinan Muftu
Keyword(s):  
Surface Roughness ◽  
Shock Waves ◽  
Supersonic Jet ◽  
Jet Impingement ◽  
Internal Surface ◽  
Supersonic Jets ◽  
Oblique Shock ◽  
Shock Interactions ◽  
Schlieren Visualization ◽  
High Reynolds

Abstract In thermal spray applications, such as cold spray, an inert gas jet (typically helium or nitrogen) is used to accelerate micron scale particles to supersonic velocities. The complex gas dynamics of these supersonic jets are critical to understand via computational methods for the control of the spray. This work compares supersonic jet waveforms visualized by schlieren imaging with those predicted by computational fluid dynamics (CFD) simulations. A supersonic nitrogen jet is produced by a millimeter scale converging-diverging nozzle with inlet pressures as high as 50 bars. The jet Reynolds numbers based on the nozzle exit diameter and stagnation gas properties range between 60,000 to 325,000. A schlieren visualization setup has been built which shows the first spatial derivative of densities within the flow field. The strong density gradients across the oblique shock waves in the jets allow for clear photographs of the flow pattern of the jets using this schlieren visualization setup. Comparisons between the experiments and the CFD results act as a validation technique for the accuracy of the simulations in terms of the positions and orientations of the oblique shock waves. Through this study, the nozzle internal surface roughness is determined to be a critical parameter in millimeter scale nozzles for the development of the boundary layer. The CFD surface roughness parameters inside the nozzle are incremented until the geometry of the oblique shock waves matches the schlieren images. This work validates the simulation techniques which will be used for future jet simulations, in which shock wave locations and orientations are important, such as jet impingement on a flat plate and particle-shock interactions.

An Assessment of Turbulence Models for S-Duct Diffusers With Flow Control

2013 ◽  
Author(s):  
S. P. Bhat ◽  
R. K. Sullerey
Keyword(s):  
Experimental Data ◽  
Flow Control ◽  
Turbulence Model ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Experimental Results ◽  
Cfd Analysis ◽  
Duct Flow ◽  
Ansys Fluent ◽  
Sst Model

The selection of a turbulence model for a problem is not trivial and has to be done systematically after comparison of various models with experimental data. It is a well known fact that there is no such turbulence model which fits all problems ([3], [13]). The flow in S-duct diffuser is a very complex one where both separation and secondary flow coexist. Previous work by the author on CFD analysis of S-duct diffuser was done using k-ε-Standard model [1], however it has been seen that choosing other turbulence model may result in better capturing of the physics in such a problem. Also flow control, to reduce energy losses, is achieved using a technique called Zero Net Mass Flow (ZNMF), in which suction and vortex generation jets (VGJ) are combined and positioned at optimum location. A proper turbulence model has to be chosen for capturing these phenomena effectively. Extensive experimental data is available on this problem and ZNMF technique from previous work done by one of the authors which is used for validating the CFD results. Here the focus is on choosing the best turbulence model for the S-duct diffuser. Numerical (CFD) analysis is carried out using Ansys Fluent 13.0 with six turbulence models for the geometry with (ZNMF) and without (Bare duct) flow control and then compared with the experimental results. The turbulence models used are Spalart-Allmaras, three variants of k-ε – Standard, RNG and Realizable and two variants of k-ω – Standard and SST model. All the parameters of comparison are non-dimensionalized using the free stream properties, so that the results are applicable to a wider range of problems. This work is limited to incompressible flow analysis, as the experimental data is only available for low Mach number flows. Comparison of all these models clearly shows that results obtained using k-ω-SST model are very comparable to the experimental results for the bare duct (without flow control) and flow controlled duct both in terms of distribution of properties and aggregate results. Compressible flow analysis can be attempted to achieve reliable results in future with ZNMF using the best turbulence model based on this study.

Sign in / Sign up

Export Citation Format

Share Document