Measurement of pressure loss and observation of the flow field in viscoelastic flow through an undulating channel

2000 ◽  
Vol 44 (1) ◽  
pp. 65-78 ◽  
Author(s):  
Takashi Koshiba ◽  
Noriyasu Mori ◽  
Kiyoji Nakamura ◽  
Shiro Sugiyama
Keyword(s):  
Flow Field ◽  
Pressure Loss ◽  
Viscoelastic Flow ◽  
Flow Through

Influence of a Honeycomb Facing on the Flow Through a Stepped Labyrinth Seal

2000 ◽  
Vol 124 (1) ◽  
pp. 140-146 ◽  
Author(s):  
V. Schramm ◽  
K. Willenborg ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Experimental Investigations ◽  
Labyrinth Seals ◽  
Numerical Predictions ◽  
Flow Through ◽  
Aero Engines

This paper reports numerical predictions and measurements of the flow field in a stepped labyrinth seal. The theoretical work and the experimental investigations were successfully combined to gain a comprehensive understanding of the flow patterns existing in such elements. In order to identify the influence of the honeycomb structure, a smooth stator as well as a seal configuration with a honeycomb facing mounted on the stator wall were investigated. The seal geometry is representative of typical three-step labyrinth seals of modern aero engines. The flow field was predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grid includes the basic seal geometry as well as the three-dimensional honeycomb structures.

Paper 3: Steady Flow Tests on Twin Poppet Valves

1967 ◽  
Vol 182 (4) ◽  
pp. 126-133 ◽  
Author(s):  
W. A. Woods
Keyword(s):  
Steady Flow ◽  
Pressure Loss ◽  
Pressure Ratio ◽  
Effective Area ◽  
Valve Lift ◽  
Cylinder Wall ◽  
Large Area ◽  
Pressure Losses ◽  
Flow Through ◽  
Poppet Valves

This paper presents the results of an experimental investigation of steady flow through a pair of exhaust poppet valves. An account is given of the gas exchange process on engines which use poppet valves and the reason why pressure losses should be kept to a minimum is explained. Tests carried out on the cylinder head of a uniflow two-stroke cycle engine are described following a brief description of the apparatus used. The results of a simple analysis of incompressible flow are also given. It is shown that the two previous models of flow through a valve, namely the sudden enlargement and constant static pressure, both give unrealistic pressure losses for large area ratios, i.e. at high valve lifts. A new model is introduced which leads to realistic pressure losses at small and large area ratios, i.e. at low and high valve lifts. Effective areas for the present tests are calculated on the basis of the constant pressure model, and details of calculation of pressure losses are outlined. The blockage effect caused by placing the exhaust valves near the cylinder wall is given in the discussion of the test results. This is zero for 0 < l/d < 0·08, but reaches a maximum blockage of 10 per cent at l/d = 0·28. With unrestricted twin valves the effective area is about twice that of a single valve up to l/d = 0·18 with a progressively larger effective area at lifts up to 13 per cent higher at l/d = 0·4. A comparison is also made with other data readily available. The pressure losses determined from the tests were analysed using a parameter derived in the simple theory. The parameter used is found to be almost independent of pressure ratio and the results are presented by means of this pressure loss parameter as a function of valve lift. The representation provides a quantitative method of comparing the performance of a given configuration of valve and port. On this basis the twin poppet valves are shown to give a slightly higher pressure loss than a single valve.

High Speed Flow Through Wire Gauzes

1959 ◽  
Vol 63 (584) ◽  
pp. 474-475 ◽  
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
High Speed ◽  
Static Pressure ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Speed Flow ◽  
Wire Gauze ◽  
Flow Through

The Flow of Fluids through screens has been widely studied with particular importance being attached to the measurement of the pressure drop caused by a screen and its relation to the screen geometry and the flow conditions. The majority of the investigations have been carried out on wire gauze screens mounted in ducts with air passing through them, the static pressure being measured on either side of the gauze. Attempts have been made by Weighardt Annand and Grootenhuisto correlate the gauze geometry with the pressure drop and to enable the pressure loss over a given screen and with given flow conditions to be predicted.

Multiphase viscoelastic flow through porous media

AIChE Journal ◽  
1968 ◽  
Vol 14 (1) ◽  
pp. 50-56 ◽  
Author(s):  
John C. Slattery
Keyword(s):  
Porous Media ◽  
Viscoelastic Flow ◽  
Flow Through Porous Media ◽  
Flow Through

scholarly journals Computational fluid dynamics simulations of the flow field characteristics in a novel exhaust purification muffler of diesel engine

2018 ◽  
Vol 37 (4) ◽  
pp. 816-833 ◽  
Author(s):  
Fu Jun ◽  
Zhang ZengFeng ◽  
Chen Wei ◽  
Mao Hong ◽  
Li JianXing
Keyword(s):  
Flow Field ◽  
Pressure Loss ◽  
Cavity Length ◽  
Great Influence ◽  
Expansion Ratio ◽  
Ceramic Foam ◽  
Length Ratio ◽  
Maximum Pressure ◽  
Flow Field Characteristics ◽  
Exhaust Purification

The purpose of this paper is to improve the emission performance of diesel engines. A novel exhaust purification muffler was proposed and designed. The flow field characteristics of the exhaust purification muffler were studied based on the finite volume method, the pressure loss of the exhaust purification muffler was 3315 Pa, and the pressure loss of the exhaust purification muffler was just 2% higher than the original muffler. Then, a three-dimensional numerical simulation model was established and used to investigate the effect of different expansion ratio, cavity length ratio, and ratio of length to diameter on the flow field characteristics in an exhaust purification muffler of diesel engine. The study was shown that the porous media (ceramic foam) had a great influence on the flow field distribution, where the air flow velocity was stable and the pressure distribution was trapezoidal, having a good pressure reduction and deceleration effect. With the increase of the expansion ratio parameter, the airflow cross-section area changed when air entered into the inlet silencing cavity, which had great influence on the velocity field and the pressure loss. Because of the improvement of cavity length ratio parameter, the flowing distance in the inlet silencing increased, which caused more local turbulence and pressure fluctuation. Also with the increase of the ratio of length to diameter parameter, the volume of inlet silencing chamber and the air flow space increased. The change of the structural parameters of each scheme had a certain influence on the pressure loss. The maximum pressure loss changing value among the expansion ratio schemes was 878 Pa, then the maximum pressure loss changing value among the cavity length ratio schemes was 328 Pa, and it was 89 Pa among the cavity length ratio schemes. The pressure loss caused by the expansion ratio parameter changed greatly, and the pressure loss changing value caused by the change of the cavity length ratio parameter and the ratio of length to diameter parameter was relatively small. In this paper, a muffler which contained a ceramic foam and had the functions of exhaust soot purification and noise elimination was supplied. The effects of the structure factors on flow field characteristics were studied. The guidance for the design and improvement of muffler is able to be supplied in this paper.

Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System

2020 ◽  
Author(s):  
Vaclav Slama ◽  
Lukas Mrozek ◽  
Bartolomej Rudas ◽  
David Simurda ◽  
Jindrich Hala ◽  
...  
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Numerical Simulations ◽  
Pressure Loss ◽  
Operational Reliability ◽  
Operating Conditions ◽  
The Real ◽  
Pressure Losses ◽  
Flow Fluctuations ◽  
Valve Assembly

Abstract Aerodynamic measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for nozzle governing of a turbine with 135MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field. It is an important task since undesirable flow fluctuations can lead to operational reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences (IT) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operating points. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve’s strainers, which were historically used in order to stabilize the flow, and without them. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From measured pressure fluctuations, it was found out where and for which conditions a danger of flow instabilities occurs. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve’s strainers are used or not. Therefore, the areas of safe and danger operational reliability can be predicted. The influence of the control valve’s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are highly overloaded. For normal operating conditions, there is no difference. As a result, the control valve’s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid with similar valve assemblies.

Semi-empirical pressure loss model for viscous flow through high aspect ratio rectangular orifices

2019 ◽  
Vol 31 (7) ◽  
pp. 073603
Author(s):  
Yishak Yusuf ◽  
Reza Sabbagh ◽  
David S. Nobes
Keyword(s):  
Aspect Ratio ◽  
Viscous Flow ◽  
High Aspect Ratio ◽  
Pressure Loss ◽  
Loss Model ◽  
Flow Through ◽  
Semi Empirical

Numerical Simulation of Cold Swirl Field for Solid Fuel Ramjet with NACA Airfoil

2014 ◽  
Vol 716-717 ◽  
pp. 711-716
Author(s):  
Jie Yu ◽  
Xiong Chen ◽  
Hong Wen Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radial Velocity ◽  
Solid Fuel ◽  
Velocity Gradient ◽  
Pressure Loss ◽  
Total Pressure ◽  
Swirl Flow ◽  
Total Pressure Loss ◽  
Swirl Number

In order to study the swirl flow characteristics in the solid fuel ramjet chamber, a new type of annular vane swirler with NACA airfoil is designed. The cold swirl flow field in the chamber is numerically simulated with different camber and t attack angle, while the swirl number , swirl flow field structure, total pressure recovery coefficient were studied. According to numerical simulation result, the main factors in swirl number are camber and angle of attack, the greater angle of attack, the greater the camber ,the stronger swirl will be. Results show that the total pressure loss is mainly concentrated in the inlet section, the total pressure loss cause by vane swirler is small. Radial velocity gradient exists in swirling flow, and increases with the swirl number. With the influence of centrifugal force and combustion chamber structure, the radial velocity gradient increases.

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