Hypersonic compression corner flow with large separated regions

2019 ◽  
Vol 877 ◽  
pp. 471-494 ◽  
Author(s):  
Sudhir L. Gai ◽  
Amna Khraibut
Keyword(s):  
Large Scale ◽  
Asymptotic Theory ◽  
Reverse Flow ◽  
Boundary Layer Separation ◽  
Recirculation Region ◽  
Hypersonic Boundary Layer ◽  
Temperature Ratio ◽  
Scale Separation ◽  
Compression Corner ◽  
Corner Flow

The structure of large-scale hypersonic boundary layer separation and reattachment is studied numerically using a flat plate/compression corner geometry. Apart from verifying the large scale separation characteristics in hypersonic flow, a detailed discussion of secondary separation and fragmentation into multiple vortices embedded within the main recirculation region is presented. The unique relation between the second minimum in shear stress and the scaled angle is highlighted in the context of the reverse flow singularity of Smith (Proc. R. Soc. Lond. A, vol. A420, 1988, pp. 21–52) and it appears that for a small wall temperature ratio, such a singularity is unlikely. It is shown that the size of the separation can be estimated in terms of Burggraf’s expression based on asymptotic theory.

scholarly journals Numerical study on the standing morphology of an oblique detonation wave under the influence of an incoming boundary layer

Open Physics ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Jin Zhou ◽  
Yu Liu ◽  
Zhi-yong Lin
Keyword(s):  
Boundary Layer ◽  
Detonation Wave ◽  
Transverse Wave ◽  
Large Scale ◽  
Numerical Study ◽  
Boundary Layer Separation ◽  
Adiabatic Wall ◽  
Scale Separation ◽  
Oblique Detonation Wave ◽  
Wall Condition

AbstractThe influence of an incoming boundary layer to the standing morphology of an oblique detonation wave (ODW) induced by a compression ramp is numerically studied in this paper. The Spalart-Allmaras (SA) turbulence model is used to perform simulation of detonationboundary- layer interactions. Three different wall conditions are applied to realize control on the boundary-layer separation scales. Accordingly, different standing morphologies of the ODWs are obtained, including smooth ODW (without transverse wave) under no-slip, adiabatic wall condition with large-scale separation, abrupt ODW (with transverse wave) under no-slip, cold wall condition with moderate-scale separation, and bow-shaped detached ODW under slipwall condition without a boundary layer.

Numerical Analysis on the CO-NO Formation Production near Burner Throat in Swirling Flow Combustion System

2014 ◽  
Vol 69 (2) ◽  
Author(s):  
Mohamad Shaiful Ashrul Ishak ◽  
Mohammad Nazri Mohd Jaafar
Keyword(s):  
Swirling Flow ◽  
Reverse Flow ◽  
Flow Behavior ◽  
Recirculation Region ◽  
Mixing Enhancement ◽  
Ansys Fluent ◽  
Pressure Losses ◽  
No Formation ◽  
Swirl Angle ◽  
Air Mixing

The main purpose of this paper is to study the Computational Fluid Dynamics (CFD) prediction on CO-NO formation production inside the combustor close to burner throat while varying the swirl angle of the radial swirler. Air swirler adds sufficient swirling to the inlet flow to generate central recirculation region (CRZ) which is necessary for flame stability and fuel air mixing enhancement. Therefore, designing an appropriate air swirler is a challenge to produce stable, efficient and low emission combustion with low pressure losses. A liquid fuel burner system with different radial air swirler with 280 mm inside diameter combustor of 1000 mm length has been investigated. Analysis were carried out using four different radial air swirlers having 30°, 40°, 50° and 60° vane angles. The flow behavior was investigated numerically using CFD solver Ansys Fluent. This study has provided characteristic insight into the formation and production of CO and pollutant NO inside the combustion chamber. Results show that the swirling action is augmented with the increase in the swirl angle, which leads to increase in the center core reverse flow, therefore reducing the CO and pollutant NO formation. The outcome of this work will help in finding out the optimum swirling angle which will lead to less emission.  

Large-scale separation of alkaloids from Corydalis decumbens by pH-zone-refining counter-current chromatography

2006 ◽  
Vol 1115 (1-2) ◽  
pp. 267-270 ◽  
Author(s):  
Xiao Wang ◽  
Yanling Geng ◽  
Fuwei Li ◽  
Xingang Shi ◽  
Jianhua Liu
Keyword(s):  
Large Scale ◽  
Zone Refining ◽  
Scale Separation ◽  
Counter Current

SPECIAL REVIEWS

PEDIATRICS ◽  
1948 ◽  
Vol 2 (4) ◽  
pp. 489-497
Author(s):  
CHARLES A. JANEWAY
Keyword(s):  
Plasma Proteins ◽  
Chemical Structure ◽  
Large Scale ◽  
Blood Donors ◽  
Red Cross ◽  
American Red Cross ◽  
Scale Separation ◽  
Medical Progress ◽  
Scientific Curiosity ◽  
Free People

This brief review of some of the recent accessions to our knowledge of the chemical structure, physiologic functions, and therapeutic applications of the plasma proteins serves to emphasize three important elements in medical progress—scientific curiosity, the humanitarian impulse, and effective social organization. We have had the privilege of summarizing the work of hundreds of investigators, whose studies are giving us new tools for the investigation and treatment of disease. Their work has only been possible because the magnificent response of a free people to the call for blood donors by a voluntary philanthropic agency, the American Red Cross, was coupled with a technical triumph, the development of practical methods for the large-scale separation of the plasma proteins, itself the culmination of highly theoretical and seemingly impractical investigations by protein chemists in various countries for many years.

INVESTIGATION ON HEAT TRANSFER ENHANCEMENT IN A CORRUGATED FIN-AND-TUBE COMPACT HEAT EXCHANGER

2016 ◽  
Vol 78 (10-2) ◽  
Author(s):  
Ahmadali Gholami ◽  
Mazlan A. Wahid ◽  
Hussein A. Mohammed ◽  
A. Saat ◽  
M. Y. M. Fairus ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Pressure Loss ◽  
Boundary Layer Separation ◽  
Performance Criteria ◽  
Recirculation Region ◽  
Moderate Pressure ◽  
Compact Heat Exchangers ◽  
Heat Transfer Augmentation

Heat transfer augmentation and pressure loss penalty in the fin-and-tube compact heat exchangers (FTCHEs) with the corrugated shape as a special form of the fin are numerically investigated to improve heat transfer performance criteria in low Reynolds numbers. The corrugated fin as the newly design of fin pattern is presented in this study. The influence of applying corrugated design adjustments on the thermal and hydraulic characteristics of air flow are analyzed on the in-line tube arrangements. The performance of air-side heat transfer and fluid flow is investigated by numerical simulation for Reynolds number ranging from Re = 400 to 800 based on the tube collar diameter, with the corresponding frontal air velocity ranging from 0.35 to 0.72 m/s. The outcomes of simulation revealed that the corrugated fin could significantly improve the heat transfer augmentation of the FTCHEs with a moderate pressure loss penalty. The computational results indicated that some eddies were developed behind the fluted domain of corrugated finwhich produce some disruptions to fluid flow and enhance heat transfer compared with plain fin. The corrugated form of fins could enhance the thermal mixing of the fluid, delay the boundary layer separation, and reduce the size of the wake and the recirculation region behind tubes compared with the conventional form of the fin at the range of Reynolds number used in this study. In addition, the results showed that the average Nusselt number for the FTCHE with corrugated fin increased by 7.05–10.0% over the baseline case and the corresponding pressure loss decreased by 5.0–6.2%.

scholarly journals Separation and Purification of Two Flavone Glucuronides fromErigeron multiradiatus(Lindl.) Benth with Macroporous Resins

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Zhi-feng Zhang ◽  
Yuan Liu ◽  
Pei Luo ◽  
Hao Zhang
Keyword(s):  
Large Scale ◽  
Raw Materials ◽  
Sorption Isotherms ◽  
Preparative Separation ◽  
Separation And Purification ◽  
Bioactive Constituents ◽  
Simple Method ◽  
Scale Separation ◽  
Adsorption And Desorption ◽  
Macroporous Resins

Scutellarein-7-O-β-D-glucuronide (SG) and apigenin-7-O-β-D-glucuronide (AG) are two major bioactive constituents with known pharmacological effects inErigeron multiradiatus. In this study, a simple method for preparative separation of the two flavone glucuronides was established with macroporous resins. The performance and adsorption characteristics of eight macroporous resins including AB-8, HPD100, HPD450, HPD600, D100, D101, D141, and D160 have been evaluated. The results confirmed that D141 resin offered the best adsorption and desorption capacities and the highest desorption ratio for the two glucuronides among the tested resins. Sorption isotherms were constructed for D141 resin under optimal ethanol conditions and fitted well to the Freundlich and Langmuir models (R2>0.95). Dynamic adsorption and desorption tests was performed on column packed with D141 resin. After one-run treatment with D141 resin, the two-constituent content in the final product was increased from 2.14% and 1.34 % in the crude extract ofErigeron multiradiatusto 24.63% and 18.42% in the final products with the recoveries of 82.5% and 85.4%, respectively. The preparative separation of SG and AG can be easily and effectively achieved via adsorption and desorption on D141 resin, and the method developed can be referenced for large-scale separation and purification of flavone glucuronides from herbal raw materials.

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