Numerical investigation of cooling performance with the use of Al2O3/water nanofluids in a radial flow system

2011 ◽  
Vol 50 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Yue-Tzu Yang ◽  
Feng-Hsiang Lai
Keyword(s):  
Numerical Investigation ◽  
Radial Flow ◽  
Flow System ◽  
Cooling Performance

Errors Associated With the Application of the G-Function Plot for Analyzing Pressure Fall-Off Tests in Water Injection Wells

2021 ◽  
Author(s):  
Jun Wu ◽  
Iraj Ershaghi
Keyword(s):  
Research Study ◽  
Radial Flow ◽  
Flow System ◽  
Water Injection ◽  
Reservoir Modeling ◽  
Injection Wells ◽  
Analysis Technique ◽  
Fracture Closure ◽  
Closing Pressure ◽  
Pressure Fall

Abstract Castillo1 suggested the use of the G-Function plot based on the work of Nolte2. It has been a standard practice in the fracturing community to estimate the fracture closing pressure from a tangent to the G*dp/dg plot. In this analysis technique, the assumption is that a fracture has already developed under the high-pressure fracturing fluid. Then when the pumping is relaxed, one can estimate the fracture closing pressure. In many California waterfloods, the issue of maximum allowable injection gradient has been debated. Various solutions have been proposed to calculate a safe injection gradient. One method that has been promoted is the application of the G-function plot. In this paper, we maintain that this application can be misleading using the prescribed cartesian G function plots. We present the results of an extensive research study for analyzing pressure fall-off data using the G-Plot function. We studied a reappraisal of the G function plot using waterflood conditions where no prior fractures had formed, and no fracture closing pressure was meaningful or applicable. We show from analysis of generated data, using both numerical reservoir modeling and analytical derivations for a radial flow system, that fall-off tests analyzed using the cartesian G function can generate false indications of fracture closing where in fact, the entire injection has been based on radial flow homogeneous injection systems. We also studied systems with a pre-existing fracture before injection. We show that if such a reservoir system is subjected to injection and fall-off tests, again, one may compute a false indication of the irrelevant fracture closure pressure. We discuss how the cartesian scale used for the G function plot can be misleading for the analysis of fall-off test data.

Numerical Investigation on Film Cooling Performance of Fusiform Diffusion Holes

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu
Keyword(s):  
Numerical Investigation ◽  
Cross Section ◽  
Film Cooling ◽  
Discharge Coefficient ◽  
Cross Sectional ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Section Area ◽  
Two Sides ◽  
Dynamics Method

This paper presents a numerical investigation of the film-cooling performance of a kind of diffusion hole with a fusiform cross section. Relative to the rectangular diffusion hole, the up- and/or downstream wall of the fusiform diffusion hole is outer convex. Under the same metering section area, six fusiform diffusion holes were divided into two groups with cross-sectional widths of W = 1.7D and W = 2.0D, respectively. Three fusiform cross section shapes in each group included only downstream wall outer convex, only upstream wall outer convex, or a combination of both. Simulations were performed in a flat plate model using a 3D steady computational fluid dynamics method under an engine-representative condition. The simulation results showed that the fusiform diffusion hole with only an outer convex upstream wall migrates the coolant laterally toward the hole centerline, and then forms or enhances a tripeak effectiveness pattern. Conversely, the fusiform diffusion hole with an outer convex downstream wall intensely expands the coolant to the hole two sides, and results in a bipeak effectiveness pattern, regardless of the upstream wall shape. Compared with the rectangular diffusion holes, the fusiform diffusion holes with only an upstream wall outer convex significantly increase the overall effectiveness at high blowing ratios. The increased magnitude is approximately 20% for the hole of W = 1.7D at M = 2.5. Besides, the fusiform diffusion holes with an outer convex upstream wall increase the discharge coefficient about 5%, within the moderate to high blowing ratio range.

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