scholarly journals Leakage-Flow Models for Screw Extruders

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1919
Author(s):  
Christian Marschik ◽  
Wolfgang Roland ◽  
Marius Dörner ◽  
Georg Steinbichler ◽  
Volker Schöppner
Keyword(s):  
Regression Models ◽  
Leakage Flow ◽  
The Novel ◽  
Flow Models ◽  
Modeling Techniques ◽  
Temperature Development ◽  
Flow Through ◽  
Pressure Flows ◽  
Screw Extruders ◽  
Theoretical Analyses

Many theoretical analyses of extrusion ignore the effect of the flight clearance when predicting the pumping capability of a screw. This might be reasonable for conventional extruder screws with “normal” clearances but leads to errors when more advanced screw designs are considered. We present new leakage-flow models that allow the effect of the flight clearance to be included in the analysis of melt-conveying zones. Rather than directly correcting the drag and pressure flows, we derived regression models to predict locally the shear-thinning flow through the flight clearance. Using a hybrid modeling approach that includes analytical, numerical, and data-based modeling techniques enabled us to construct fast and accurate regressions for calculating flow rate and dissipation rate in the leakage gap. Using the novel regression models in combination with network theory, the new approximations consider the effect of the flight clearance in the predictions of pumping capability, power consumption and temperature development without modifying the equations for the down-channel flow. Unlike other approaches, our method is not limited to any specific screw designs or processing conditions.

scholarly journals Temperature development in the leakage flow of screw extruders

1978 ◽  
Vol 18 (4) ◽  
pp. 288-292 ◽  
Author(s):  
H. E. H. Meyer ◽  
J. F. Ingen Housz ◽  
W. C. M. Gorissen
Keyword(s):  
Leakage Flow ◽  
Temperature Development ◽  
Screw Extruders

Modeling Critical Flow Through Steam Generator Tube Cracks

2014 ◽  
Author(s):  
Andrew Oussoren ◽  
Jovica R. Riznic ◽  
Shripad Revankar
Keyword(s):  
Steam Generator ◽  
Critical Flow ◽  
Steam Generator Tube ◽  
Flow Rates ◽  
Flow Models ◽  
Modeling Techniques ◽  
Small Flow ◽  
Flow Through ◽  
Experimental Values ◽  
Similar Accuracy

Modeling of leakage rates through geometries representative of steam generator tube cracks is being investigated. These cracks are characterised by very small flow areas and low length to diameter ratios. Two sets of experiments were conducted by researchers at Purdue University measuring flow rates through several slits in 3.175 mm and 1.3 mm thick samples, with L/D ratios as low as 1.2. A pressure differential of 6.8 MPa was applied across the samples with varying degrees of subcooling. Flow rates through these samples were modeled using the thermal-hydraulic system codes RELAP and TRACE, using different nodalization techniques and both the Henry Fauske and Ransom Trapp critical flow models available in RELAP. Model results are compared to experimental values and modeling techniques are discussed. TRACE and RELAP were found to have similar accuracy in predicting flow rate trends, with higher accuracy at larger L/D. In general best results were achieved by modeling the crack as a junction component.

Film cooling characteristics on blade platform with a leakage flow through mid-passage gap

2021 ◽  
Vol 167 ◽  
pp. 120800
Author(s):  
Sehjin Park ◽  
Ho-Seong Sohn ◽  
Sangwoo Shin ◽  
Osamu Ueda ◽  
Hee Koo Moon ◽  
...  
Keyword(s):  
Film Cooling ◽  
Leakage Flow ◽  
Flow Through

Numerical Analysis of Leakage Flow Through Two Labyrinth Seals

2007 ◽  
Vol 19 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Wei-zhe Wang ◽  
Ying-zheng Liu ◽  
Pu-ning Jiang ◽  
Han-ping Chen
Keyword(s):  
Numerical Analysis ◽  
Leakage Flow ◽  
Labyrinth Seals ◽  
Flow Through

Leakage flow analysis in the gas turbine shroud gap

2019 ◽  
Vol 91 (8) ◽  
pp. 1077-1085 ◽  
Author(s):  
Filip Wasilczuk ◽  
Pawel Flaszynski ◽  
Piotr Kaczynski ◽  
Ryszard Szwaba ◽  
Piotr Doerffer ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Gas Turbine ◽  
Mass Flow ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Original Design ◽  
Reference Case ◽  
Content Type ◽  
Flow Through ◽  
The Impact

Purpose The purpose of the study is to measure the mass flow in the flow through the labyrinth seal of the gas turbine and compare it to the results of numerical simulation. Moreover the capability of two turbulence models to reflect the phenomenon will be assessed. The studied case will later be used as a reference case for the new, original design of flow control method to limit the leakage flow through the labyrinth seal. Design/methodology/approach Experimental measurements were conducted, measuring the mass flow and the pressure in the model of the labyrinth seal. It was compared to the results of numerical simulation performed in ANSYS/Fluent commercial code for the same geometry. Findings The precise machining of parts was identified as crucial for obtaining correct results in the experiment. The model characteristics were documented, allowing for its future use as the reference case for testing the new labyrinth seal geometry. Experimentally validated numerical model of the flow in the labyrinth seal was developed. Research limitations/implications The research studies the basic case, future research on the case with a new labyrinth seal geometry is planned. Research is conducted on simplified case without rotation and the impact of the turbine main channel. Practical implications Importance of machining accuracy up to 0.01 mm was found to be important for measuring leakage in small gaps and decision making on the optimal configuration selection. Originality/value The research is an important step in the development of original modification of the labyrinth seal, resulting in leakage reduction, by serving as a reference case.

scholarly journals Study on Flow Boiling Characteristics in Rectangle Channel After Formation of Blisters

2021 ◽  
Vol 9 ◽  
Author(s):  
Huijian Huang ◽  
Chong Chen ◽  
Luguo Liu ◽  
Yu Liu ◽  
Linfeng Li ◽  
...  
Keyword(s):  
Flow Boiling ◽  
The Novel ◽  
Local Flow ◽  
Flow Through ◽  
Cfd Method ◽  
Dry Out ◽  
Fuel Elements ◽  
Type Fuel ◽  
Plate Type ◽  
Structure Choice

Plate-type fuel elements is one of the first fuel structure choice for the novel integrated PWR, however, blisters will appear on the cladding induced by irradiation and fission. In this work CFD method was used to investigate the subcooled boiling characteristic of the water in rectangle channel with round and pillow blisters, the modified RPI model was also proposed, we can draw conclusions as follows: In the channel with round blister, as the blisters will increase the local flow resistance and more fluid will flow through center of the channel. Boiling occurred only in the area near the edges, nearly no vapor appeared at the center of the channel. The boiling region in channel with pillow shape blisters is wider and concentrated between two pillow blisters and downstream of the non-blisters side. The dry out area are both in the downstream region of blisters for the two types of channels.

scholarly journals The novel solution of ball valve with replaceable orifice. Numerical and field tests

2019 ◽  
Vol 9 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Grzegorz Romanik ◽  
Janusz Rogula
Keyword(s):  
Power Plant ◽  
Experimental Verification ◽  
Theoretical Approach ◽  
Field Tests ◽  
Ball Valve ◽  
Numerical Calculations ◽  
Compressed Air ◽  
The Novel ◽  
Measuring Device ◽  
Flow Through

AbstractThe article presents the results of numerical calculations and experimental results of a flow through the orifice. Such a measuring device was built-into the ball valve that gave unique possibility of the orifice exchange without the pipeline disassemble. The advantages of using the prototypical solution has been described. This patented solution has been tested extensively for the durability and tightness. The article contains comparison between flow character in the case of single-hole orifice and a multi-nozzle one. The prototypical measuring device has been produced and assembled in compressed air system in the Power Plant Opole, that gave experimental verification of theoretical approach.

A Review of Nonsteady Flow Models for Compressor Stability

1994 ◽  
Vol 116 (2) ◽  
pp. 202-215 ◽  
Author(s):  
J. P. Longley
Keyword(s):  
Fluid Dynamics ◽  
Flow Field ◽  
Rotating Stall ◽  
Time Development ◽  
Mathematical Treatment ◽  
Two Dimensional ◽  
Nonsteady Flow ◽  
Physical Processes ◽  
Flow Models ◽  
Modeling Techniques

This paper presents a review of the different approaches to modeling the nonsteady fluid dynamics associated with two-dimensional compressor flow fields. These models are used to predict the time development of flow field disturbances and have been found useful in both the study of rotating stall and the development of active control. The opportunity to digest the earlier investigations has now made it possible to express the modeling ideas using only a very simple mathematical treatment. Here, the emphasis is on the underlying physical processes that the models simulate and how the assumptions within the models affect predictions. The purpose of this work is to produce, in a single document, a description of compressor modeling techniques, so that prospective users can assess which model is the most suitable for their application.

Theoretical Modelling of Relative Wall Motion Effects in Tip Leakage Flow

1995 ◽  
Author(s):  
I. K. Nikolos ◽  
D. I. Douvikas ◽  
K. D. Papailiou
Keyword(s):  
Wall Motion ◽  
Tip Clearance ◽  
Calculation Procedure ◽  
Theoretical Modelling ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Complete Calculation ◽  
Flow Through ◽  
Good Agreement

The influence of relative wall motion in modifying the leakage flow through the tip clearance is investigated. A theoretical model is developed, in order to calculate the mass flow rate through the gap. The physical mechanism by which relative wall motion affects the leakage flow is analyzed and the differences between the turbine and compressor case are identified. This model, being an extension of an already existing one, not taking into account relative wall motion, is incorporated into the tip clearance calculation procedure, already developed by the authors. Theoretical results of the complete calculation procedure (secondary flow plus tip clearance model) are compared with experimental data, for the case of compressor and turbine cascades, as well as for the case of a single rotor. Good agreement between theory and experiment is obtained.

Sign in / Sign up

Export Citation Format

Share Document