Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
High Speed ◽  
Experimental Results ◽  
Turbulent Regime ◽  
Frequency Of Occurrence ◽  
Visualization Method ◽  
Entire Flow

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

Experimental Study of a Variable Pressure Damper on Automotive Valve Motion

1996 ◽  
Author(s):  
Jin-Jang Liou ◽  
Grodrue Huang ◽  
Wensyang Hsu
Keyword(s):  
Experimental Study ◽  
Friction Coefficient ◽  
Friction Force ◽  
High Speed ◽  
Experimental Results ◽  
Variable Pressure ◽  
Friction Forces ◽  
Valve Spring ◽  
Valve Motion

Abstract A variable pressure damper (VPD) is used here to adjusted the friction force on the valve spring to investigate the relation between the friction force and the valve bouncing phenomenon. The friction force on the valve spring is found experimentally, and the corresponding friction coefficient is also determined. Dynamic valve displacements at different speeds with different friction forces are calibrated. Bouncing and floating of the valve are observed when the camshaft reaches high speed. From the measured valve displacement, the VPD is shown to have significant improvement in reducing valve bouncing distance and eliminating floating. However, experimental results indicate that the valve bouncing can not be eliminated completely when the camshaft speed is at 2985 rpm.

The effect analysis of an engine jet on an aircraft blast deflector

2018 ◽  
Vol 41 (4) ◽  
pp. 990-1001
Author(s):  
Song Ma ◽  
Jianguo Tan ◽  
Xiankai Li ◽  
Jiang Hao
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
High Speed ◽  
Deflection Angle ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Experimental Results ◽  
Exhaust Gases ◽  
The Impact

This paper establishes a novel mathematical model for computing the plume flow field of a carrier-based aircraft engine. Its objective is to study the impact of jet exhaust gases with high temperature, high speed and high pressure on the jet blast deflector. The working condition of the nozzle of a fully powered on engine is first determined. The flow field of the exhaust jet is then numerically simulated at different deflection angle using the three-dimensional Reynolds averaged Navier–Stokes equations and the standard [Formula: see text]-[Formula: see text] turbulence method. Moreover, infra-red temperature tests are further carried out to test the temperature field when the jet blast deflector is at the [Formula: see text] deflection angle. The comparison between the simulation results and the experimental results show that the proposed computation model can perfectly describe the system. There is only 8–10% variation between them. A good verification is achieved. Moreover, the experimental results show that the jet blast deflector plays an outstanding role in driving the high-temperature exhaust gases. It is found that [Formula: see text] may be the best deflection angle to protect the deck and the surrounding equipment effectively. These data results provide a valuable basis for the design and layout optimization of the jet blast deflector and deck.

An experimental study of high-speed rotor supported by air bearings: test RIG and first experimental results

2006 ◽  
Vol 39 (8) ◽  
pp. 839-845 ◽  
Author(s):  
Guido Belforte ◽  
Terenziano Raparelli ◽  
Vladimir Viktorov ◽  
Andrea Trivella ◽  
Federico Colombo
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Experimental Results ◽  
Air Bearings ◽  
Test Rig

Experimental Study of Kick up Phenomenon in Thermosonic Wire-Bonding

2012 ◽  
Vol 160 ◽  
pp. 77-81
Author(s):  
Jing Jing Tian ◽  
Lei Han
Keyword(s):  
Image Processing ◽  
Experimental Study ◽  
High Speed ◽  
Gold Wire ◽  
Wire Bonding ◽  
Processing Method ◽  
Experimental Results ◽  
High Speed Camera ◽  
Depth Study ◽  
Thermosonic Wire Bonding

Kick-up phenomenon during looping is an important factor in thermosonic wire bonding. In this study, the loping process during wire bonding was recorded by using high-speed camera, and wire profiles evolution was obtained from images sequence by image processing method. With a polynomial fitting, the wire loop profiling was described by the curvature changing, and kick-up phenomenon on gold wire was found between the instant of 290th frame(0.0537s) to 380th frame (0.0703s), the change of curvature is divided into three phases, a looping phase, a mutation phase and a kick-up phase. While in the kick-up phase, the kick up phenomenon is the most obvious. These experimental results were useful for in-depth study of kick-up phenomenon by simulation.

Experimental Study on the Response Characteristics of Oilcans under High-Velocity Fragment Impact

2012 ◽  
Vol 510 ◽  
pp. 500-506
Author(s):  
Chang Hai Chen ◽  
Xi Zhu ◽  
Hai Liang Hou ◽  
Li Jun Zhang ◽  
Ting Tang
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
High Speed ◽  
Room Temperature ◽  
Experimental Results ◽  
Fuel Oil ◽  
High Speed Camera ◽  
Response Characteristics ◽  
Fuel Oils ◽  
The Impact

To explore the deflagration possibility of the warship cabin filled with fuel oil under impact of high-speed fragments in the condition of room temperature, experiments were carried out employing the small aluminium oilcans filled with fuel oil. Response processes of the oilcans were observed with the help of a high-speed camera. The disintegration as well as flying scattering of the oilcans were analyzed. The reasons for atomization of the fuel oils were presented. Finally, the deflagration possibility of warship oil cabin was analyzed. Results show that the pressure inside the oilcan is quite great under the impact of the high-speed fragment, which makes the oilcan disintegration and flying scattering. Simultaneously, fuel oils inside the oilcans are atomized quickly followed by ejected in front and back directions. Under the same condition as in present tests, deflagration will not occur for fuel oils used by warships. Experimental results will provide valuable references for the deflagration analysis of warship fuel oil cabins subjected to the impact of high-velocity fragments.

Experimental Visualization Study on the Explosion Process of Gasoline Vapor in Narrowly-Confined Space

2013 ◽  
Vol 791-793 ◽  
pp. 2108-2111 ◽  
Author(s):  
Jian Jun Liang ◽  
Yang Du ◽  
Yi Hong Ou ◽  
Xin Sheng Jiang ◽  
Hai Bing Qian ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Data Acquisition ◽  
High Speed ◽  
Development Stage ◽  
High Speed Camera ◽  
Confined Space ◽  
Vapor Explosion ◽  
Gasoline Vapor ◽  
Explosion Process

In this paper, experimental study on gasoline vapor explosion was conducted with data acquisition technology of high-speed camera. In the experiments, the flame behaviors and the flow field movements were shot by the high-speed camera, the space pressure were recorded by high-speed dynamic tester, and the explosion process were analyzed refinedly and intuitively. Studies have shown that according to variations of flame behaviors and pressure characteristics, process of gasoline vapor explosion can be divided into four stages: the ignition stage, the development stage, the intensification stage and the plume stage.

An Experimental Study of Influence of Slits in Throat Position on Suppression of Cavitation Instabilities in Liquid Propellant Rocket Inducer

2019 ◽  
Author(s):  
Moena Kanamaru ◽  
Yoshito Kamikura ◽  
Satoshi Kawasaki ◽  
Takashi Shimura ◽  
Iga Yuka
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Pressure Fluctuation ◽  
High Speed ◽  
Cavity Length ◽  
High Speed Camera ◽  
Liquid Propellant ◽  
Suppression Effect ◽  
Suction Performance ◽  
Propellant Rocket

Abstract Experiments of an inducer with symmetric slits were conducted. The purpose of the study is to explore the suppression effect on cavitation instabilities by slits. The slits are located in a throat position in each blade and it means symmetric slits. The experiments are done through measuring pressure fluctuation in the flow field and shaft displacement and visualization using high speed camera. In this study, the head performance, the suction performance, the cavity length and the occurrence range and the strength of the cavitation instabilities are compared with the results of inducer without slit. As a result, the slit in throat position does not give bad effect on head performance, improves suction performance, and has a relation to suppression of oscillation of cavitation instabilities because of the suppression effect of cavity length, although the occurrence range of super-synchronous rotating cavitation unfortunately increases because the cavity develops slowly.

scholarly journals Prediction of 3-D Viscous Flow of Centrifugal Impeller With Tip-Clearance: Part 1 — High Speed Compressor

1997 ◽  
Author(s):  
E. Y. K. Ng
Keyword(s):  
Flow Field ◽  
Viscous Flow ◽  
High Speed ◽  
Flow Patterns ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Suction Surface ◽  
Compressor Rotor ◽  
Entire Flow

This paper described a 3-D, finite-volume procedure for simulating the entire viscous flow field within the impellers of a high subsonic radial compressor with uniform tip-clearance. The aim of the calculation is to verify the compressible Navier-Stokes solvers by comparing the computation against the experimental data of Krain backswept compressor at choke condition. The time-marching implicit technique used is a modified form of the basic Beam-Warming algorithm with a mixing length turbulence model in the blade-relative frame using rotating cylindrical coordinate system and appropriate source terms. An outline of the scheme is addressed and the present capabilities of the solver are assessed. The numerical calculations of the well-known jet/wake-type flow patterns agree well with measurement for the compressor rotor, and detailed comparisons indicate that the tip-clearance effect must be accurately modeled to compute the impeller flow patterns properly. In the case of larger separation region near suction surface of Krain compressor, it is due to the larger tip gap used in the model which causes the thickening of the casing boundary layer followed by the deterioration of the entire flow field.

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