The Influence of Supersonic Combustion when the Cavity Parameters Changed on the Chamber Wall

2012 ◽  
Vol 468-471 ◽  
pp. 2620-2623
Author(s):  
Peng Gao ◽  
Xin Long Chang ◽  
Shuang Lin Gao ◽  
Jie Tang Zhu
Keyword(s):  
Flow Field ◽  
Numerical Simulations ◽  
High Efficiency ◽  
Supersonic Combustion ◽  
Chamber Wall ◽  
Flame Stability ◽  
Hydrogen Fuel ◽  
Research Results ◽  
Scramjet Combustor ◽  
Air Mixing

In this paper, the detail numerical simulations were performed on the flow field of the scramjet combustor chamber with the hydrogen fuel, when the cavity parameters changed. The research results indicate that the effect of gas and air mixing and flame stability are altered when the parameter of cavity changed. From the research we will better understand the supersonic combustion. The high efficiency flame stabilities can be designed in future.

Effects of Blade Outlet Width on Flow Field and Characteristic of Centrifugal Pumps

2009 ◽  
Author(s):  
Ming-gao Tan ◽  
Hou-lin Liu ◽  
Shou-qi Yuan ◽  
Yong Wang ◽  
Kai Wang
Keyword(s):  
Flow Field ◽  
Flow Curve ◽  
High Efficiency ◽  
Field Analysis ◽  
Centrifugal Pumps ◽  
Research Results ◽  
Rotor Stator Interaction ◽  
Nominal Condition ◽  
Specific Speed ◽  
Width Change

The present deficiency about numerical simulation research on blade outlet width of centrifugal pumps is pointed out. In the case of different outlet widths, the flow field in six centrifugal pumps whose specific speed vary from 45 to 260 are simulated by using commercial code FLUENT and the characteristics are predicted. The standard k-ε turbulence model and SIMPLEC algorithm are chosen in FLUENT. The simulation is steady and moving reference frame is used to consider rotor-stator interaction. The research results show that the change of impeller outlet width has obvious impacts on characteristics at design point, flow field and the shape of performance curves. At nominal condition, the change of outlet width has more important effects on moderate specific speed centrifugal pumps. The flow field analysis indicates that blade outlet width change has an important effect on the location and area of low pressure region behind the blade inlet, jet-wake structure in impellers, the secondary flow in volute cross section and the back flow in impellers. The head-flow curve becomes more flat with the increase of outlet width. For moderate and low specific speed centrifugal pumps, the high efficiency area of efficiency-flow curve get bigger with the increase of outlet width and the area will be constant within certain outlet width change scope for high specific speed centrifugal pump. The research results agree well with experiment results.

scholarly journals Tandem-wing interactions on aerodynamic performance inspired by dragonfly hovering

2021 ◽  
Vol 8 (8) ◽  
pp. 202275
Author(s):  
Liansong Peng ◽  
Mengzong Zheng ◽  
Tianyu Pan ◽  
Guanting Su ◽  
Qiushi Li
Keyword(s):  
Body Weight ◽  
Flow Field ◽  
Numerical Simulations ◽  
Phase Difference ◽  
High Efficiency ◽  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
The Body ◽  
Wing Surface ◽  
Phase Differences

Dragonflies possess two pairs of wings and the interactions between forewing (FW) and hindwing (HW) play an important role in dragonfly flight. The effects of tandem-wing (TW) interactions on the aerodynamic performance of dragonfly hovering have been investigated. Numerical simulations of single-wing hovering without interactions and TW hovering with interactions are conducted and compared. It is found that the TW interactions reduce the lift coefficient of FW and HW by 7.36% and 20.25% and also decrease the aerodynamic power and efficiency. The above effects are mainly caused by the interaction between the vortex structures of the FW and the HW, which makes the pressure of the wing surface and the flow field near the wings change. During the observations of dragonfly flight, it is found that the phase difference ( γ ) is not fixed. To explore the influence of phase difference on aerodynamic performance, TW hovering with different phase differences is studied. The results show that at γ = 22.5°, dragonflies produce the maximum lift which is more than 20% of the body weight with high efficiency; at γ = 180°, dragonflies generate the same lift as the body weight.

The Numerical Research on the Scramjet Combustion with Different Structure Cavity

2012 ◽  
Vol 468-471 ◽  
pp. 1444-1447 ◽  
Author(s):  
Peng Gao ◽  
Xin Long Chang ◽  
Lei Luo ◽  
Yu Ji Cao
Keyword(s):  
Numerical Simulations ◽  
Combustion Chamber ◽  
Fuel Combustion ◽  
Hydrogen Fuel ◽  
Mixed Fuel ◽  
Research Results ◽  
Numerical Research

In this paper, the detailed numerical simulations were performed in the hydrogen fuel combustion chamber with some different structure cavities. Through the analysis found that the effect of stabilized fire burning at supersonic flowing and mixed fuel and air are quite different. The research results will preferably represent the burning field in scramjet combustion so that the better performance flame stabilizer can be designed.

scholarly journals Direct Measurements of Skin Friction in Supersonic Combustion Flow Fields

1992 ◽  
Author(s):  
K. M. Chadwick ◽  
D. J. Deturris ◽  
J. A. Schetz
Keyword(s):  
Skin Friction ◽  
Fuel Injection ◽  
Force Measurement ◽  
Tangential Force ◽  
Transverse Component ◽  
Supersonic Combustion ◽  
Quartz Tube ◽  
Hydrogen Fuel ◽  
Sensor Head ◽  
Scramjet Combustor

An experimental investigation was conducted to measure skin friction along the chamber walls of supersonic combustors. A direct force measurement device was used to simultaneously measure an axial and transverse component of the small tangential shear force passing over a non-intrusive floating element. This measurement was made possible with a sensitive piezoresistive deflection sensing unit. The floating head is mounted to a stiff cantilever beam arrangement with deflection due to the flow on the order of 0.00254 mm (0.0001 in). This allowed the instrument to be a non-nulling type. A second gauge was designed with active cooling of the floating sensor head to eliminate non-uniform temperature effects between the sensor head and the surrounding wall. The key to this device is the use of a quartz tube cantilever with piezoresistive strain gages bonded directly to its surface. A symmetric fluid flow was developed inside the quartz tube to provide cooling to the backside of the floating head. Tests showed that this flow did not influence the tangential force measurement. Measurements were made in three separate combustor test facilities. Tests at NASA Langley Research Center consisted of a Mach 3.0 vitiated air flow with hydrogen fuel injection at Pt = 500 psia (3446 kPa) and Tt = 3000 R (1667 K). Two separate sets of tests were conducted at the General Applied Science Laboratory (GASL) in a scramjet combustor model with hydrogen fuel injection in vitiated air at Mach = 3.3, Pt = 800 psia (5510 kPa), and Tt = 4000 R (2222 K). Skin friction coefficients between 0.001–0.005 were measured dependent on the facility and measurement location. Analysis of the measurement uncertainties indicate an accuracy to within ±10–15% of the streamwise component.

A Review of Fuel Pre-injection in Supersonic, Chemically Reacting Flows

2007 ◽  
Vol 60 (4) ◽  
pp. 139-148 ◽  
Author(s):  
Viacheslav A. Vinogradov ◽  
Yurii M. Shikhman ◽  
Corin Segal
Keyword(s):  
Dynamic Pressure ◽  
Reacting Flows ◽  
Supersonic Combustion ◽  
Liquid Fuels ◽  
Mixing Efficiency ◽  
Flame Stability ◽  
Chemically Reacting Flows ◽  
Air Mixing ◽  
Chemically Reacting ◽  
Supersonic Aerodynamics

Developing an efficient, supersonic combustion-based, air breathing propulsion cycle operating above Mach 3.5, especially when conventional hydrocarbon fuels are sought and particularly when liquid fuels are preferred to increase density, requires mostly effective mechanisms to improve mixing efficiency. One way to extend the time available for mixing is to inject part of the fuel upstream of the vehicle’s combustion chamber. Injection from the wall remains one of the most challenging problems in supersonic aerodynamics, including the requirement to minimize impulse losses, improve fuel-air mixing, reduce inlet∕combustor interactions, and promote flame stability. This article presents a review of studies involving liquid and, in selected cases, gaseous fuel injected in supersonic inlets or in combustor’s insulators. In all these studies, the fuel was injected from a wall in a wake of thin swept pylons at low dynamic pressure ratios (qjet∕qair=0.6–1.5), including individual pylon∕injector geometries and combinations in the inlet and combustor’s isolator, a variety of injection conditions, different injectants, and evaluated their effects on fuel plume spray, impulse losses, and mixing efficiency. This review article cites 47 references.

Direct Measurements of Skin Friction in Supersonic Combustion Flow Fields

1993 ◽  
Vol 115 (3) ◽  
pp. 507-514 ◽  
Author(s):  
K. M. Chadwick ◽  
D. J. DeTurris ◽  
J. A. Schetz
Keyword(s):  
Skin Friction ◽  
Fuel Injection ◽  
Force Measurement ◽  
Tangential Force ◽  
Transverse Component ◽  
Supersonic Combustion ◽  
Quartz Tube ◽  
Hydrogen Fuel ◽  
Sensor Head ◽  
Scramjet Combustor

An experimental investigation was conducted to measure skin friction along the chamber walls of supersonic combustors. A direct force measurement device was used to measure simultaneously an axial and a transverse component of the small tangential shear force passing over a nonintrusive floating element. This measurement was made possible with a sensitive piezoresistive deflection sensing unit. The floating head is mounted to a stiff cantilever beam arrangement with deflection due to the flow on the order of 0.00254 mm (0.0001 in). This allowed the instrument to be a nonnulling type. A second gage was designed with active cooling of the floating sensor head to eliminate nonuniform temperature effects between the sensor head and the surrounding wall. The key to this device is the use of a quartz tube cantilever with piezoresistive strain gages bonded directly to its surface. A symmetric fluid flow was developed inside the quartz tube to provide cooling to the backside of the floating head. Tests showed that this flow did not influence the tangential force measurement. Measurements were made in three separate combustor test facilities. Tests at NASA Langley Research center consisted of a Mach 3.0 vitiated air flow with hydrogen fuel injection at Pt = 500 psia (3466 kPa) and Tt = 3000 R (1667 K). Two separate sets of tests were conducted at the General Applied Science Laboratory (GASL) in a scramjet combustor model with hydrogen fuel injection in vitiated air at Mach = 3.3, Pt = 800 psia (5510 kPa), and Tt = 4000 R (2222 K). Skin friction coefficients between 0.001–0.005 were measured dependent on the facility and measurement location. Analysis of the measurement uncertainties indicate an accuracy to within ± 10–15 percent of the streamwise component.

Flow-Field-Assisted Dielectrophoretic Microchips for High-Efficiency Sheathless Particle/Cell Separation with Dual Mode

2021 ◽  
Author(s):  
Shitao Shen ◽  
Zichuan Yi ◽  
Xing Li ◽  
Shuting Xie ◽  
Mingliang Jin ◽  
...  
Keyword(s):  
Flow Field ◽  
Cell Separation ◽  
High Efficiency ◽  
Dual Mode

scholarly journals Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 593-603 ◽  
Author(s):  
Zivan Spasic ◽  
Sasa Milanovic ◽  
Vanja Sustersic ◽  
Boban Nikolic
Keyword(s):  
Numerical Simulations ◽  
High Efficiency ◽  
Suction Side ◽  
Standard Test ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Blade Profile ◽  
Operating Characteristics ◽  
Axial Fan ◽  
Increase Energy Efficiency

The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

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