Performance Analyses of the Spiral Groove Dry Gas Seal with Inner Annular Groove

2013 ◽  
Vol 420 ◽  
pp. 51-55 ◽  
Author(s):  
Ying Li ◽  
Peng Yun Song ◽  
Heng Jie Xu
Keyword(s):  
Pressure Control ◽  
Operating Conditions ◽  
Performance Parameters ◽  
Spiral Groove ◽  
Dry Gas Seal ◽  
Sealing Performance ◽  
The Common ◽  
The Difference ◽  
Film Stiffness ◽  
The Given

In order to improve the performance of the spiral groove dry gas seal (S-DGS), the spiral groove dry gas seal with an inner annular groove (AS-DGS) was invented. Based on the narrow groove theory, the sealing performance parameters of the AS-DGS were gained by using approximate analytical method to solve the gas film pressure control equations, and the results were compared with those of the common S-DGS. The results show that, in the given operating conditions, the opening force of AS-DGS is smaller than that of the S-DGS with the difference less than 0.5%, and the film stiffness is larger than that of the common S-DGS with the difference less than 5% in the case of low-speed or high-pressure operation, but the leakage is a little larger.

The influence of 3-DOF film thickness disturbance on transient performance of typical spiral groove dry gas seals

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yuan Chen ◽  
Hao Shang ◽  
Xiaolu Li ◽  
Yuntang Li ◽  
Bingqing Wang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Degrees Of Freedom ◽  
Thickness Distribution ◽  
Transient Performance ◽  
Spiral Groove ◽  
Double Row ◽  
Content Type ◽  
Dry Gas Seal ◽  
Sealing Performance ◽  
Gas Seals

Purpose The purpose of this paper is to investigate the influence rule and mechanism of three degrees of freedom film thickness disturbance on the transient performance of spiral groove, upstream pumping spiral groove dry gas seal (UP-SDGS) and double-row spiral groove dry gas seal (DR-SDGS). Design/methodology/approach The transient performance of spiral groove, UP-SDGS and DR-SDGS are obtained by solving the transient Reynolds equation under different axial and angular disturbance coefficients. The transient and steady performance of the above-mentioned DGSs are compared and analyzed. Findings The film thickness disturbance has a remarkable impact on the sealing performance of DGS with different structures and the calculation deviations of the leakage rate of the UP-DGS will increase significantly if the film thickness disturbance is ignored. The axial and angular disturbance jointly affect the film thickness distribution of DGS, but there is no significant interaction between them on the transient sealing performance. Originality/value The influence mechanism of axial disturbance and angular disturbance on the transient performance of typical SDGSs behavior has been explained by theory. Considering small and large disturbance, the interaction between axial disturbance and angular disturbance on the transient performance have been studied.

Development of a Misfire Detection’s Technique Based on an Engine’s Torsional Model

2006 ◽  
Author(s):  
Davide Moro ◽  
Stefano Pantaleoni ◽  
Gabriele Serra
Keyword(s):  
Experimental Tests ◽  
Calibration Procedure ◽  
Angular Speed ◽  
Operating Conditions ◽  
False Alarms ◽  
Hall Effect Sensor ◽  
The Common ◽  
The Difference ◽  
New Diagnosis ◽  
Misfire Detection

The recent OBD requirements enforce the misfire’s diagnosis and the isolation of the cylinder where the missing combustion took place. Most of the common-used techniques developed are based on the engine’s angular speed, that is derived by the signal usually measured with an inductive or Hall-effect sensor already used for the engine’s control. The presence of single or multiple misfires (several misfires within the same engine’s cycle) induces torsional vibration in the powertrain, requiring specific filtering of the diagnostic signal to avoid false alarms. This paper presents some preliminary results, related to a 4 cylinder 1.2 liter engine mounted on an eddy-current brake test bench, obtained by a new diagnosis technique based on two speed sensors, placed near the toothed wheels used respectively for the engine and current brake’s control. The signals coming from the two sensors, applied to an equation derived by a torsional model of the engine powertrain, allow to evaluate an index based on the difference between engine and brake’s torque that highlights the misfire presence. It will be shown that this index does not require any particular calibration procedure. Experimental tests, in which single and multiple misfires are induced in several operating conditions, show clearly the algorithm’s robustness in misfire detection, especially in multiple misfire tests, where the misfiring cylinders are exactly detected.

Hydrodynamics and Sonic Flow Transition in Dry Gas Seals

2014 ◽  
Author(s):  
Azam Thatte ◽  
Xiaoqing Zheng
Keyword(s):  
Linear Partial Differential Equation ◽  
Hydrodynamic Pressure ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Spiral Groove ◽  
Local Pressure ◽  
Choked Flow ◽  
Gas Seals ◽  
Film Stiffness

Dry gas seals (DGS) are widely used in turbomachinery applications. They are recently being also recommended for sealing novel super critical CO2 turbomachinery space. However, these seals can render interesting behavior under certain operating conditions which needs to be carefully monitored so that intended level of dynamic characteristics can be achieved. The ability of these seals to maintain low leakage by riding at small clearances makes them an attractive solution where secondary flows need to be minimized. To understand the significance of some of the key design features of these seals, in this work an analysis on a gas lubricated spiral groove dry gas seal is presented. Equations in polar coordinates governing the compressible flow through the DGS gap and a numerical method to solve such non-linear partial differential equation is presented. The resulting sets of equations are solved for hydrodynamic pressure distribution and the axial separation force and the film stiffness at the rotor-stator interface is calculated. A detailed study on key spiral groove features is then performed to investigate the effect of spiral angle, groove depth, groove pitch and dam width ratio on the hydrodynamic pressure generation capacity, film stiffness and hence on overall performance of the DGS. Another important phenomenon that can occur in DGS under high operating pressure is the sonic transition. It is shown that choked flow under such conditions can take place over the dam section of the seal which manifests itself into large local pressure and temperature variations and can result into dynamic instabilities.

scholarly journals Linguistic Data Model for Natural Languages and Artificial Intelligence. Part 4. Language

Discourse ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 107-114
Author(s):  
O. M. Polyakov
Keyword(s):  
Artificial Intelligence ◽  
Natural Language ◽  
Natural Languages ◽  
New Approach ◽  
Linguistic Model ◽  
The World ◽  
Human World ◽  
The Common ◽  
The Difference ◽  
The Given

Introduction. The paper continues a series of publications on linguistics of relations (hereinafter R–linguistics) and is devoted to questions of the formation of a language from a linguistic model of the world. Moreover, the language is considered in its most general form, without taking into account the grammatical component. This allows you to focus on the general problems of language formation. Namely, this allows us to show why language adequately reflects the model of the world and what are the features of the transition from model to language. This new approach to language is relevant in connection with the formation of an understanding of the common core in all natural languages, as well as in connection with the needs for the formation of artificial intelligence subsystems of interaction with humans.Methodology and sources. Research methods consist in the formulation and proof of theorems about language spaces and their properties. The materials of the paper and the given proofs are based on the previously stated ideas about linguistic spaces and their decompositions into signs.Results and discussion. The paper shows how, in the most general form, the formation of language structures takes place. Namely, why does language adequately reflect the linguistic model, and what is the difference between linguistic and language spaces? The concepts of an open and closed form of the language are formulated, as well as the law of form. Examples of open and closed forms of the language are shown. It is shown that the formation of the language allows you to compensate for the lack of real signs in the surrounding world while maintaining the prognostic properties of the model.Conclusion. Any natural language is a reflection of the human world model. Moreover, all natural languages are similar in terms of the principles of forming the core of the language (language space). Language spaces standardize the models of the world by equalizing real and fictional signs of categories. In addition, the transition to language simplifies some of the problems of pattern recognition and opens the way to the logic of natural language.

scholarly journals The Influence of Using the Traction Booster of the Semi‑Mounted Plough on the Performance Parameters of the Ploughing Set

2018 ◽  
Vol 66 (2) ◽  
pp. 381-388 ◽  
Author(s):  
Lukáš Renčín ◽  
Adam Polcar ◽  
František Bauer
Keyword(s):  
Fuel Consumption ◽  
Confidence Intervals ◽  
Positive Influence ◽  
Performance Parameters ◽  
Effective Performance ◽  
The Difference ◽  
The Given

The objective of this article is to verify the influence of the use of the traction cylinder of the semi‑mounted plough on the performance parameters of the ploughing set., Claas Axion 850 set, equipped with Hexashift mechanical stepped gearbox, fully geared under the load of Pöttinger semi-mounted plough was used for the purposes of the measurement. Assessed parameters included force in the upper rod, slip, effective performance of the set and fuel consumption. The results of the measurement clearly indicate the positive influence of the traction booster on the performance and energetic parameters of the ploughing set. By increasing the force in the upper rod, the torque is transferred to the land-wheel which partially relieves the furrow wheel and transfers the weight pertaining to this wheel to the land-wheel. This has decreased the slip (between 0 – 15 MPa: 7.5 % for plant-bed wheel and 2 % for furrow wheel) and increased the performance of the set (hectare efficiency was increased by 3.7 %) while reducing consumption and eliminating the undesirable compaction. The difference of effective consumption was between the pressure 0 and 15 MPa 0,6 l/ha which corresponds to a decrease of 2.6 % and 2.89 ml/m3, equal to a decrease of 3.9 %. Except for some exceptions, the changes of the monitored parameters were not statistically significant. This was caused especially due to the conditions of the measurement and also due to the chosen aggregation. The measured values fluctuated due to soil non-homogeneity, which was subsequently reflected in the size of the confidence intervals and due to the fact that the tractor was under-dimensioned for the given conditions and the plough construction, the influence of the traction booster has not been proven to such an extent.

Enhancing Film Stiffness of Spiral Groove Dry Gas Seal via Shape Modification at Low Speed: Numerical Results and Experiment

2019 ◽  
Vol 62 (6) ◽  
pp. 931-942 ◽  
Author(s):  
Jinbo Jiang ◽  
Xudong Peng ◽  
Cong Zong ◽  
Wenjing Zhao ◽  
Yuan Chen ◽  
...  
Keyword(s):  
Numerical Results ◽  
Spiral Groove ◽  
Shape Modification ◽  
Low Speed ◽  
Dry Gas Seal ◽  
Film Stiffness

scholarly journals THE PHENOMENON OF ANTONOMASIA IN LANGUAGE AND SPEECH (BASED ON ENGLISH PRESS)

2020 ◽  
Vol 1 (10(78)) ◽  
pp. 48-51
Author(s):  
Olesya Tatarovska
Keyword(s):  
Single Case ◽  
Distinctive Features ◽  
Potential Subject ◽  
New Name ◽  
The Subject ◽  
The Common ◽  
The Difference ◽  
Own Name ◽  
The Given ◽  
Stylistic Device

Antonomasia can not be confidently attributed to a single case of metonymy or metaphor, as antonomasia is based on whether similar or on adjacent identifying objects. In speech antonomasia is a stylistic device, namely, the conscious use of existing or creation of a new name, which is realized together with the given value and is subject-logical at the same time. This leads to the fact that the name not only identifies the object, but characterizes it differently. Depending on whether the common name is transferred to its own (that is, the basis of the new name of the own name is the subject-logical value of the existing common name) or the potential subject-logical value of the embodied name is obtained in the foreground, we distinguish two types of antonomasia. This option indicates not the primary referent of the name, but its characteristics, distinctive features. However, the reference equivalence remains, but may be gradually erased. If it completely disappears, it causes the creation of a new common name. Considering antonomasia from the position of the nomination act, we can characterize it both as a process, and as a result of nominative activity. It is also worth recognizing the difference between antonomasia that characterizes the unit of speech, i.e. its own name, which has a potential subject-logical value implemented in certain contexts, and antonomasia as a stylistic device, i.e., special use of the name in context to achieve certain pragmatic effects.

Ḥadith ‘Āishah fī Man’i al-Nisā’ Min al-Masājid; Niqāsh ‘Ulamā’ Bangladesh Ḥaulahu

2020 ◽  
Vol 9 (1) ◽  
pp. 97-115
Author(s):  
Syed Mahmudul Hasan
Keyword(s):  
Analytical Method ◽  
Inductive Method ◽  
The Common ◽  
The Difference ◽  
Common Situation

The Narration of Aisyah (May Allah be pleased with her), is the main focus of the controversy among Bangladeshi scholars on the issue of women's prayer in the mosque. The reason for the dispute is that a group of them issued the ruling based on the phenomenon of the text, and the others explained the ruling of Hadith according to the common situation in the society. If the circumstances change, the ruling will change along with it, because the originality of the issue is permissible, that is proven from other texts. This research adopts an inductive method to survey the Prophetic hadiths that talk about the prayer of women in the Mosque in terms of permissibility and prohibition and analytical method to analyze the difference in opinion of Bangladeshi scholars related to this issue. The research finds that the ruling of Shari’ah is a process that is continuous and permanent. But in necessity and emergency, it has the notion of flexibility and explanation. In the issue of women’s presence in the mosque, they should be allowed if they abide by the suggestions of Prophet (s) and should not if they don’t. So, Prohibition is not from the prophet (s), but it is from their obedience to the ruling.

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