Enhancing the surge margin of a Centrifugal Compressor with different Blade Tip Geometry

The reliability operation for small fuel cells and hybrid fuel cell with gas turbine requires centrifugal compressor surge prevention. This study concerns a high speed centrifugal compressor stage with different blade tip geometries. The investigations were performed with unsteady three-dimensional, compressible flow simulations. A novel parameterization method has been developed to alter the tip geometry of an impeller blade. Different tip geometries are investigated includes flat tip blade, main blade winglet, main and splitter blade winglet and finally pressure side grooved tip. The performance and internal flow results are presented at surge, design and near choke points. The conclusion is that the tip geometry has a significant effect on the compressor performance and the operation stability at lower flow rates. The pressure ratio and surge margin for the blades with winglet have been improved, and decreased for the grooved tip geometry. More uniform flow at impeller outlet with winglet blade. The use of winglet tip displaces the tip leakage vortex away from the blade and weakening the impingement effect. The winglet tip reduces the aerodynamic losses by unloading the tip section, reducing the leakage flow rate and turning the leakage flow in a more stream wise direction

Dry gas seat simulation with different spiral tapered grooves / Ibrahim Shahin … [et al.]

The flow and performance analysis for a dry gas seal (DGS) with a standard and tapered spiral grooves is developed using a verified FLUENT CFD model. A comprehensive analysis is proposed to resolve the effect of modifying the seal grooves geometry on gas film pressure distribution and the seal performance. The effect of the fluid state and the rotational speed on the gas seal performance and internal flow field are studied and presented. The fluid state effect on the gas seal internal flow and performance is studied, Laminar and turbulent flow with RNG K-e turbulence model and LES is examined for the same geometrical and operating conditions. Also different rotational speed effect on gas seal performance is examined for 0, 2500, 5000, 7500 and 10380 rpm. Three taper spiral grooves are studied each with three different angles, including taper grooves in the radial, circumferential and combined radial-circumferential directions. The laminar flow simulation for the dry gas seal agree well with the experimental results more than the turbulent flow simulation which overestimate the pressure distribution inside the seal. The results indicate that as the rotational speed increase the seal open force and leakage increase. The use of tapered type spiral groove causes a reduction in the seal open force and the leakage rate. Increasing the angle of radial taper groove reduces the temperature distribution inside the gas film. The Reduction in seal open force and leakage rate is higher when use combined Radial-circumferential taper more than radial and circumferential taper used

Influence of deep excavation on behavior of adjacent single pile: effect of pile location

Even when located atop piles, deep excavations might result in Settlement and harm to nearby buildings. This work aims to investigate single-pile reactions to deep-braced excavation-induced soil movement in soft clay with a sand covering. The main goal of the experiment is to determine how a vertical single pile responds to produced axial force, lateral deflection, induced bending moment, and pile settlement. The pile\u27s diameter (dp) is 5 meters, and its embedded length (Lp) is 22 meters. The pile horizontally from the diaphragm wall is situated 3.75 meters (.25 He). The pile was simulated using the Embedded pile structural element. To enhance comprehension of the behavior of a single pile, a parametric analysis was conducted. to offer more information regarding the pile\u27s response. Design, procedure, and strategy A thorough three-dimensional numerical study is performed to explore pile responses during a nearby deep-braced excavation using the explicit finite element code PLAXIS 3D. Conclusions: The acquired data made it possible to fully comprehend the phenomena of soil-pile-structure interactions as well as the pile reaction. The results show that there could be significant axial forces, lateral deflections, and bending moments in the surrounding piles as a result of the deep excavation. Parametric research revealed that the position of the pile has a significant impact on the pile reactions. This work used 3D numerical modeling to fully examine the pile reaction in multi-layered soil. In this investigation, the Hardening soil model with small-strain stiffness was employed to account for the soil\u27s nonlinear small-strain behavior

Influence of deep excavation on behavior of adjacent single pile: effect of pile location

Even when located atop piles, deep excavations might result in Settlement and harm to nearby buildings. This work aims to investigate single-pile reactions to deep-braced excavation-induced soil movement in soft clay with a sand covering. The main goal of the experiment is to determine how a vertical single pile responds to produced axial force, lateral deflection, induced bending moment, and pile settlement. The pile\u27s diameter (dp) is 5 meters, and its embedded length (Lp) is 22 meters. The pile horizontally from the diaphragm wall is situated 3.75 meters (.25 He). The pile was simulated using the Embedded pile structural element. To enhance comprehension of the behavior of a single pile, a parametric analysis was conducted. to offer more information regarding the pile\u27s response. Design, procedure, and strategy A thorough three-dimensional numerical study is performed to explore pile responses during a nearby deep-braced excavation using the explicit finite element code PLAXIS 3D. Conclusions: The acquired data made it possible to fully comprehend the phenomena of soil-pile-structure interactions as well as the pile reaction. The results show that there could be significant axial forces, lateral deflections, and bending moments in the surrounding piles as a result of the deep excavation. Parametric research revealed that the position of the pile has a significant impact on the pile reactions. This work used 3D numerical modeling to fully examine the pile reaction in multi-layered soil. In this investigation, the Hardening soil model with small-strain stiffness was employed to account for the soil\u27s nonlinear small-strain behavior

Three Dimensional Computational Study for Spiral Dry Gas Seal with Constant Groove Depth and Different Tapered Grooves

AbstractThe three dimensional simulation for dry gas seal with constant depth spiral grooves and with different taper grooves is done using ANSYS FLUENT CFD code. Grid independence study and code validation are done with experimental work. The fluid state effect on the gas seal internal flow and performance is studied. The laminar and turbulent flow with RNG K-ɛ turbulence model and LES is examined for the same geometrical and operating conditions. The influence of film thickness for constant depth groove gas seal is simulated for 2, 3 and 4μm film. The effect of different rotational speeds on gas seal performance is examined for 0, 2500, 5000, 7500 and 10380rpm. Three taper spiral grooves are studied each with three different angles, including taper grooves in the radial, circumferential and combined radial-circumferential directions. The laminar flow simulation for the dry gas seal agree well with the experimental results more than the turbulent flow simulation which overestimate the pressure distribution inside the seal. The results indicate that as the rotational speed increases the seal open force and leakage increase. The use of tapered type spiral groove causes a reduction in the seal open force and the leakage rate. Increasing the angle of radial taper groove reduces the temperature distribution inside the gas film. The reduction in seal open force and leakage rate is higher when the combined radial-circumferential taper is more than radial and circumferential taper used

Roadmap for recommended guidelines of leak detection of subsea pipelines

The leak of hydrocarbon-carrying pipelines represents a serious incident, and if it is in a gas line, the economic exposure would be significant due to the high cost of lost or deferred hydrocarbon production. In addition, the leakage of hydrocarbon could pose risks to human life, have an impact on the environment, and could cause an image loss for the operating company. Pipelines are designed to operate at full capacity under steady-state flow conditions. Normal operations may involve day-to-day transients such as the operations of pumps, valves, and changes in production/delivery rates. The basic leak detection problem is to distinguish between the normal operational transients and the occurrence of non-typical process conditions that would indicate a leak. To date, the industry has concentrated on a single-phase flow, primarily of oil, gas, and ethylene. The application of a leak-monitoring system to a particular pipeline system depends on environmental issues, regulatory imperatives, loss prevention of the operating company, and safety policy rather than pipe size and configuration. This paper provides a review of the recommended guidance for leak detection of subsea pipelines in the context of pipeline integrity management. The paper also presents a review of the capability and application of various leak detection techniques that can be used to offer a roadmap to potential users of the leak detection systems. © 2024 by the authors

GTL Diesel Way Forward to Improve Properties by Separating Light Ends and Formulating the Specifications

Gas-To-Liquid (GTL) Diesel fuel produced from synthetic crudes obtained from natural gas that is converted by the Fisher Tropsch (FT) technology is a promising key player for the mobility industry future along with conventional diesel fuels. The main distinctive properties that distinguish between GTL Diesel and conventional Diesel fuels include density, viscosity, lubricity and Cetane Index. The aim of this study was to identify the effect of the change in GTL Diesel’s composition and boiling range on its market specifications, then to develop predictive models for the GTL Diesel properties based on the fuel’s composition. The study recommends how the industry can use these data for upgrading the fuel quality based on distribution market demand. Intensive testing to analyze many characteristics for GTL Diesel was done at Texas A&M University at Qatar (TAMUQ), and ORYX GTL Company provided the GTL Diesel samples. The study was divided into two sections; the first section consisted of the experimental and modeling work where multiple GTL Diesel cuts were initially prepared. The properties of the prepared cuts were analyzed for five critical GTL Diesel fuel market specifications: Density, Viscosity (kinematic and dynamic), Flash point, Cetane index and Cold properties (Pour and Cloud points). In the second section, these properties were compared with the original market specifications in order to identify whether an improvement in fuel characteristics is obtained. In the third section, the properties of these fuel cuts are used to generate mathematical models for properties-compositions relationships. Finally, we proposed certain modifications to the existing GTL Plants that will improve the separation of specific quality of fuels and value-added chemicals cut. This study also identified the potentials for the light cuts obtained from GTL Diesel fuel to be used for the production of Linear Alkyl Benzene (LAB), which is considered as an expensive value-chemical and a feedstock to detergents manufacturing plants

Women in the Whirlpool: Traversing the Tie-up of Personality and Work-Life Balance of Pakistani Academicians

This research strives to explain the impact of personality type on the work-life balance of women academicians. With the positivist paradigm and quantitative approach, this study has been conducted with a survey methodology. Data was collected from 362 women academicians on adopted instruments and analyzed with multiple regression and ANOVA tests. Results revealed a positive effect of agreeableness, extraversion, and openness personality types on work-life balance. Those women academicians who are with agreeableness personalities are more in a capacity to manage their work-life balance. The results also show a difference in managing the work-life balance between those who are single and married, those who belong to a nuclear family, and those who belong to joint or extended families. This study will facilitate them to develop the personality type which has more capacity to manage work-life balance. It will help policymakers to facilitate women academicians to ensure better work-life balance.JEL Classification: M12How to Cite:Shahin, S., Baloch, M. N., Shaikh, N., Ibrahim, I., & Abbassi, A. A. (2021). Women in the Whirlpool: Traversing the Tie-up of Personality and Work-Life Balance of Pakistani Academicians. Etikonomi, 20(2), xx – xx. https://doi.org/10.15408/etk.v20i2.17272

Ouch! How Embodied Damage Indicators in First-Person Shooting Games Impact Gaming Experience

Abstract. In this paper we present results from an exploratory study on firstperson shooting game damage indicators, comparing a red flash, a paper doll, and an x-ray mechanism, observing impact on gaming experience. Introduction and Related Work In first-person shooting games players interact with virtual worlds through multiple modalities (first-person graphics, spatial sound, movement) from the perspective of a virtual character, with the aim of enabling the player to experience the game as the character. While creating a first-person gaming experience it is not entirely feasible to cause pain to a player when the character receives an injury, and so games attempt to replicate aspects of getting an injury without actually causing pain. In this paper we explore how damage indication methods impact players emotional and cognitive experience of gameplay, rather than other metrics such as task efficiency (e.g., best score) -an approach termed "affective ludology" Evaluation of a person's affective state, and correlating it with measures of immersion and enjoyment, are still active research problems with various facets ranging from qualitative analysis of written questionnaires and interview

On the aero acoustic and internal flows structure in a centrifugal compressor with hub side cavity operating at off design condition

This paper covers the characterization of the acoustic noise and the unsteady flow field of a high speed centrifugal compressor NASA CC3. In order to accurately predict the noise, all analyses are carried out through the use of Large Eddy Simulation and Ffowcs Williams–Hawkings model for noise prediction. The relative effect of hub cavity on flow characteristics and sound levels is investigated, for a compressor stage with a total pressure ratio equal to 4, working from surge to near choke condition. In comparison with the experimental results from literature, the predicted compressor performance and flow field are predicted well, some trends seen in experiments are captured. The hub cavity flow effect on the compressor aero acoustic generated noise is shown in the paper. The unsteady static pressure and sound pressure levels are compared not only at different location but also for design and off design operating points. The internal flow results inside the hub cavity are presented at surge, design and near choke points. The conclusion is that the cavity effect of the centrifugal compressor cannot be ignored in the numerical prediction of aerodynamic generated noise. The impeller back plate of the rotor experiences a strong pressure fluctuation, which is maxima at the impeller outer radius for all operating point, but higher pressure values at the surge point.This publication was made possible by NPRP grant No. 4-651-2-242 from the Qatar National Research Fund (a member of Qatar Foundation)