Types Of Test Sections Research Articles

A Study on the Effect of Hollow Tubular Flange Sections on the Behavior of Cold-Formed Steel Built-Up Beams

This paper deals with a study conducted on flexural behavior of cold-formed steel built-up I-beams with hollow tubular flange sections. There were two types of test sections, namely, built-up sections that were assembled with either stiffened or unstiffened channels coupling back-to-back at the web and a hollow tubular rectangular flange at the top and bottom of the web to form built-up I-beam. The flexural behavior along with the strength and failure modes of the built-up sections was examined using the four-point loading system. Nonlinear finite element (FE) models were formulated and validated with the experimental test results. It was observed that the developed FE models had precisely predicted the behavior of built-up I-beams. Further, the verified FE models were used to conduct a detailed parametric study on cold-formed steel built-up beam sections with respect to thickness, depth, and yield stress of the material. The flexural strength of the beams was designed using the direct strength method as specified in American Iron and Steel Institute (AISI) for the design of cold-formed steel structural members and was compared with the experimental results and the failure loads predicted from FE models. Since the results were not conservative, a new customized design equation had been mooted and delineated in the study for determining the flexural strength of cold-formed steel built-up beams with hollow tubular flange sections.

Design and performance of a small-scale aeroacoustic wind tunnel

The D5 aeroacoustic wind tunnel at Beihang University is a newly commissioned small-scale closed-circuit wind tunnel with low turbulence intensity and low background noise. The wind tunnel is built to study both aerodynamic and aeroacoustic performance of aircraft components or scaled models. The wind tunnel has two types of test sections, the closed type test section is used for aerodynamic tests while the open type test section is mainly used for aeroacoustic experiments. Both types of test section are 1m in height and 1m in width, and the maximum wind velocity in the test section can be up to 80m/s. An anechoic chamber is built surrounding the test section to provide the non-reflecting condition. This paper provides an overview of design criteria and performance of the small-scale wind tunnel. The layout of the wind tunnel and some critical design treatments to improve aerodynamic and acoustic performance are discussed in detail. Some experiments are conducted to verify the performance of D5 wind tunnel, results confirm that the turbulence intensity is less than 0.08% in the core of test section and the background noise is comparable with other aeroacoustic wind tunnels. A scaled simplified nose landing gear model is also measured as a benchmark test, results reveal that noise radiated from the model is adequately higher than the background noise for a wide frequency range and remarkably consistent with other results from literatures.

Experimental Results of Pebble Bed Thermal-Hydraulic Characteristics

The purpose of this paper is to present the results of the experimental investigation of the thermal-hydraulic characteristics for two types of test sections: thin annular pebble beds (i.e., spheres dumped in thin annular slots) and pebble beds placed between cylinders. The experimental results of heat transfer from the spheres and from a cylinder, as well as hydraulic drag for both types of test sections, are presented in this paper. The results of the thin annular pebble bed experiments demonstrate that the maximum heat transfer and hydraulic drag is at the annular slot with the relative width K equal to 1.07 and 1.75 of the sphere diameter. The heat transfer in the internal layers at these values of K is equal to the heat transfer in the internal layers of large (unlimited) rhombic packing. The results of the experimental investigation of pebble beds between cylinders demonstrate that the randomly arranged pebble bed is preferable to the regular rhombic structure from the viewpoints of design simplicity, heat transfer from the cylinder, and drag coefficient.

Experimental Investigation of Heat Transfer and Flow Mixing in Pebble Beds

The purpose of this paper is to investigate the thermal hydraulic characteristics of two types of test sections: pebble beds placed between cylinders and thin annular pebble beds (i.e., spheres dumped in thin annular slots). The investigations were performed for axial air flow. The experimental results of heat transfer from the spheres, as well as the results of heat transfer from a cylinder for both types of test sections, are presented. In addition, the results of flow-mixing investigations in pebble beds between axially streamlined cylinders are described. From these results, correlations were developed that can be used to predict the heat transfer characteristics. The results of the experimental investigation of pebble beds between cylinders demonstrated that the randomly arranged pebble bed is preferable to the regular rhombic structure from the points of view of design simplicity, heat transfer from the cylinder, drag coefficient, and flow mixing. The results of the experiments in the case of thin annular pebble beds demonstrated that the maximum heat transfer from the spheres is at the relative width of the annular slot K, equal to 1.07 and 1.75 of the sphere's diameter

Critical Heat Flux and Onset of Nucleate Boiling Tests in a Finned Rod Bundle

Critical heat flux (CHF) tests using rod bundles were performed under low-flow conditions to supplement the CHF database for HANARO fuel. The test rod had the same geometric configuration as the HANARO fuel, and its aluminum cladding with fins was made by coextrusion on the stainless steel heating tube. Three types of test sections were used: hexagonal with seven rods, triangular with three rods, and rectangular with four rods. Each test bundle has three spacers axially, and a view window is located in the upper region of the test section. Flow patterns until the CHF condition are typically varied from bubbly flow to annular flow, and then CHF occurs through the long annular flow period. A total of 36 bundle CHF data were obtained from the 3 test sections. The results showed that the CHFs for bundles are larger than those for a single rod with the same geometrical dimension by a maximum 26% as the mass flux changes. It is considered that these results are induced by the enhancement of the turbulence and thermal mixing generated by the spacers. In addition, measurement of the onset of nucleate boiling (ONB) in the rectangular bundle was attempted using sound signals. A hydrophone was attached near the outlet wall of the test section. Hydrophone signals around the ONB point were measured and analyzed based on the frequency through the real fast Fourier transform. Frequency analysis showed clear differences in the power spectral densities for two different frequency ranges before and after ONB, which verifies the usefulness of sound signals for ONB detection.

Review of existing research on microgravity boiling and two-phase flow: future experiments on the international space station.

This paper describes research objectives on boiling and two-phase flow under microgravity conditions from both scientific and technological points of view. Existing research for various systems in flow boiling are briefly reviewed and problems indicated for research conducted by available facilities with short microgravity duration. A wide range of experimental subjects that become possible by using different types of test sections is clarified and the validity of long term experiments is emphasized. A first step outline is described for a test loop with interchangeable test sections, such as transparent heated tubes, transparent flat heating surfaces, and narrow channels optimized for individual objectives and restricted by specifications of the facility.

A New Facility for Measurements of Three-Dimensional, Local Subcooled Flow Boiling Heat Flux and Related Critical Heat Flux for PFCs

In the development of plasma-facing components for fusion reactors and high-heat-flux heat sinks (or components) for electronic applications, the components are usually subjected to a peripherally nonuniform heat flux. Even if the applied heat flux is uniform in the axial direction (which is unlikely), both intuition and recent investigations have clearly shown that both the local heat flux and the eventual critical heat flux (CHF) in this three-dimensional (3-D) case will differ significantly from similar quantities found in the voluminous body of data for uniformly heated flow channels. Although this latter case has been used in the past as an estimate for the former case, more study has become necessary to examine the 3-D temperature and heat flux distributions and related CHF. Work thus far has shown that the nonuniform peripheral heat flux condition enhances CHF in some cases.To avoid the excess costs associated with using electron or ion beams to produce the nonuniform heat flux, a new facility was developed that will allow 3-D conjugate heat transfer measurements and two-dimensional, local subcooled flow boiling heat flux and related CHF measurements.The configurations under study for this work consist of (a) a nonuniformly heated cylinder-like test section with a circular coolant channel bored through the center and (b) a monoblock that is a square cross-section parallelepiped with a circular drilled flow channel along the channel centerline. The theoretical or ideal cylinder-like test section would be a circular cylinder with half (-90 to 90 deg) of its outside boundary subjected to a uniform heat flux and the remaining half insulated. For the monoblock, a uniform heat flux is applied to one of the outside surfaces, and the remaining surfaces are insulated. The outside diameter of the cylinder-like test section is 30.0 mm, and its length is 200.0 mm. The monoblock square is 30.0 mm long. The inside diameter of the flow channel for both types of test sections is 10.0 mm. Water is the coolant. The inlet water temperature can be set at any level in the range from 26.0 to 130.0°C, and the exit pressure can be set at any level in the range from 0.4 to 4.0 MPa. Thermocouples were placed at 48 locations inside the solid cylinder-like or monoblock test section to obtain 3-D wall temperature variations and related local heat flux. Finally, the mass velocity can be set at any level in the range from 0.4 to 10.0 Mg/m2·s for the 10.0-mm-diam channel.

Effects of the spacer and mixing vanes on critical heat flux for low-pressure water at low-velocities

The effects of spacer grids and mixing vanes on critical heat flux (CHF) have been experimentally investigated for low-pressure water at low, using two different types of test sections: an annulus (19-mm I.D., 33.5-mm O.D., 0.7-m long) and a round tube (10.8-mm I.D. and 0.7-m long). An obstruction-type spacer and a split-vane-type mixing vane were used for the annulus and round tube test sections, respectively. The spacer or mixing vane generally increase the CHF for flow rates higher than a threshold; however, they do not affect or even decrease the CHF under lower flow rates. The major contributing mechanisms would be (a) directing entrained liquid droplets to the heated wall (positive effect) and (b) break-up of the liquid film in annular flow (negative effect).

Pressurized Water Reactor Fuel Assembly Subchannel Void Fraction Measurement

The void fraction measurement experiment of pressurized water reactor (PWR) fuel assemblies has been conducted since 1987 under the sponsorship of the Ministry of International Trade and Industry as a Japanese national project. Two types of test sections are used in this experiment. One is a 5 x 5 array rod bundle geometry, and the other is a single-channel geometry simulating one of the subchannels in the rod bundle. Wide gamma-ray beam scanners and narrow gamma-ray beam computed tomography scanners are used to measure the subchannel void fractions under various steady-state and transient conditions. The experimental data are expected to be used to develop a void fraction prediction model relevant to PWR fuel assemblies and also to verify or improve the subchannel analysis method. The first series of experiments was conducted in 1992, and a preliminary evaluation of the data has been performed. The preliminary results of these experiments are described.