No abstract

A study of the effect of secondary fluid injection through single nontangential slots on the surface heat transfer in regions near the injection site is presented. The nondimensional parameters governing the heat transfer are obtained from the pertinent differential equations, and experimental results were obtained which cover the range of interest of these parameters for many situations encountered in film cooling applications. The experimental heat transfer rates were obtained from a novel transient test facility, and are presented as ratios of the heat transfer obtained with film injection to the heat transfer obtained with only the single mainstream.

Results are presented from an experimental study conducted to determine friction coefficient behavior in OCTG connections. The study was conducted using the OCTG friction and galling tester at Texas Tech University. The tester employs tubular pin and box specimen pairs fabricated from 73-mm (2 7/8 in.) diameter OCTG tubing. Friction coefficient was determined for test specimens made of material grades L80 and J55 at loads of up to 620 kN (140,000 lb) acting on a surface area of up to 645 mm2 (1 in.2) with sliding velocities of 0.53 and 1.78 cm/s (1 and 3.5 ft/min), and nominal surface roughnesses of 0.37, 1.2, and 1.5 micron (15, 47, and 60 μin.) Ra. An API Modified thread compound was used for all tests. When plotted versus the applied load, the friction coefficient behavior is seen to be highly nonlinear. In addition to load, the variables of sliding velocity, material, and surface roughness are shown to have an effect. Preliminary experiments show that the test surface geometry also has a significant effect on the friction coefficient.

The results of galling experiments are strongly dependent on the method used and vary from test machine to test machine. However, by a well-developed test method and testing machine, one can obtain reliable and repeatable results. The primary objective of this research is to develop a new test method and machine for evaluating galling resistance in OCTG (oil country tubular goods) connections. Through the application of basic principles of statistical design of experiments, the galling resistance in OCTG threaded connections has been investigated. For estimating the nominal failure stress, two statistical methods, namely, up-and-down and frequency distribution, have been applied and compared. Galling resistance, one of the most important design factors of OCTG connections, has been studied and discussed.

Results are presented from an experimental study which demonstrates the feasibility of using an existing galling tester and test method as a screening device for evaluating thread compound additives for galling protection. The galling tester employs tubular pin and box specimen pairs fabricated from steel tubing used in the oil field. For the test thread compounds, four different additive packages were used, all with the same grease base of lithium stearate. For reference purposes, the lithium stearate grease base without any additives was tested as one of the thread compounds. The data obtained on contact stress at galling failure show that of the five thread compounds tested, the best galling protection is afforded by the API Modified thread compound, the industry standard for casing and tubing used by the oil industry. The other four compounds show lower galling failure contact stresses of varying degrees. Friction coefficient data obtained during the tests are also presented and discussed.