[en] A cassette particularly for supporting a gamma radiography film is discussed. The cassette comprises a channel section bar with two flanges to which a tube is welded. A cooling fluid is made to flow through said tube. The film needs cooling when hot, recently welded parts are inspected for weld defects

[en] In the present study, flow field and film-cooling effectiveness of several double-jet film-cooling geometries on a flat plate are measured. The streamwise distance varies as s/d = 3.0, 4.0, 5.0, and 6.0, while three spanwise distance conditions (p/d) are considered. The density ratio varies as DR = 1.0, 1.5, and 2.5. Both effects of the streamwise distance and the density ratio are focused. Results show, though the streamwise distance effect is not monotonic for all the cases, a general trend is witnessed when comparing with the baseline of s/d = 3.0. For p/d = 0, with an increased streamwise distance, the lateral coverage widens and the laterally averaged effectiveness rises. However, for p/d = 0.5 and 1.0, increasing the s/d may weaken the interaction between the two jets, and reduce the film coverage and effectiveness. With an increased density ratio, the jet momentum decreases, therefore better attachment and higher film-cooling effectiveness are obtained. However, in most cases, the range of lateral coverage is mainly dominated by the spanwise distance, rather than the streamwise distance or the density ratio. By comparing the area averaged effectiveness, an optimal DJFC configuration (among the geometries in this study) is identified for each operation condition.

[en] In the present study, the influence of coolant supply condition was investigated, the coolant supply at the hole entrance were considered to be either a plenum condition or a coolant cross-flow condition. The results indicated that at low blowing ratio M=0.5, the coolant supply channel structure has little effect on film cooling performance, however, at high blowing ratio M=1.0, the adiabatic wall film cooling effectiveness was significantly different between the plenum case and the cross-flow cases. In general, for the plenum condition, film cooling is better at M=0.5 than M=1.0, while for the cross-flow condition, the film cooling effectiveness is better at blowing ratio M=0.5 in the near hole region, while at further downstream region, the film cooling effectiveness is better at M=1.0. (authors)

[en] Highlights: • A coupled method is established to simulate transpiration cooling under hypersonic condition. • The downstream film cooling effect derived by transpiration cooling is systematically analyzed. • An innovative composite cooling concept combining transpiration and film cooling is proposed. • A single channel coolant supply scheme to realize non-uniform coolant allocation is exhibited. -- Abstract: Aimed at solving the thermal protection problems of the leading edge and entire structure of hypersonic vehicles synchronously, this paper presents an innovative conception of active thermal protection, which combines transpiration and film cooling within separate porous matrixes, and a coupled numerical method to simulate the combined cooling effect of the entire field. The numerical method is validated by experimental data obtained at Ma = 4.2 in an arc-heated wind tunnel. Using gaseous Nitrogen as coolant: (1) the downstream film cooling effect derived by upstream transpiration cooling is systematically investigated; (2) the comprehensive cooling effects of two layouts of porous matrix, single porous matrix (SPM) and binary porous matrixes (BPM), are compared in detail; (3) a single channel coolant supply scheme is designed to realize desired non-uniform coolant allocation for BPM. These discussions and results are valuable for the designers searching for large area thermal protection and light weight systems.

[en] The paper represents an overview of the design study of a divertor system with liquid metal coolant (gallium) related to ARIES project. The work has been conducted by a group of specialists from Institute of Nuclear Fusion of Russian Scientific Center Kurchatov Institute within the scope of subcontract No. E212601 with General Atomics, San Diego, CA, USA. The key features of the proposed divertor design concept based on the specific LM coolant properties are as follows: (1) the requirement of the vacuum tightness of the divertor cooling tract is dismissed; (2) the pressurized coolant ducts can be separated from the plasma facing structure (PFS) elements which are subject to the thermal loads, and with this feature PFS can be replaced independently, without disturbing the cooling system; this is achieved with using free LM jets sprayed on the back side of the PFS elements, free LM film cooling and free LM draining under the action of gravity force. The divertor design has been developed formally as particularly applicable to ARIES-II reactor, the major reason for this being the choice of a vanadium-based alloy as the structural material compatible with gallium. Though there are some good prospects that carbon based materials including SiC-composite might be compatible with gallium as well. Then this concept could be used also in ARIES-IV and this possibility should be kept in mind for future

[en] This paper deals with a numerical investigation of the film cooling effectiveness on five different curved surfaces and a flat surface. The models consist of 11 rectangular cross-sectioned injection holes aligned in a single row. The blowing ratios are from 0.5 to 2.0, and the injection angle with respect to the horizontal plane is 30^o. The hole geometry, the slope of the curved surface and the blowing ratio have important effects on the film cooling effectiveness. The results show that the film cooling effectiveness of a given curved surface, both along the mainstream and the spanwise direction, depends on the optimum selection of the parameters mentioned above

[en] Highlights: • Large eddy simulation is used to study the detailed flow field of trenched holes. • The different flow structures for compound angles of 0° and 90° are investigated. • The flow fields at different coolant inflow orientations are summarized. • The influence of coolant inflow orientations is reduced by trenched holes. -- Abstract: The trenched-hole film cooling with different compound angles and coolant inflow orientations is investigated at the blowing ratio of M = 1.0 by large eddy simulation (LES). The compound angle (CA) is 0° and 90° which are commonly used in the actual application. The plenum inflow directions include the inflow fed from the plenum base (VP), the coolant orientation into the plenum vertical to (VV) and parallel to (PM) the mainstream flow. Results show that the compound angle of 90° generates a downstream asymmetrical vortex and increases the complexity of flow characteristics. This vortex is related to the low-speed recirculation region in the jet tube. Nevertheless, the trenched hole of CA = 90° improves the lateral coolant coverage, compared with CA = 0°. The coolant inflow orientations have been demonstrated to exert a significant effect on film cooling effectiveness for the round and shaped hole. The trench hole of CA = 0° narrows the difference of velocity distribution on the trench exit due to the redistribution of coolant in the trench. For CA = 90°, the decline of cooling effectiveness declines more obviously while the plenum inflow direction is vertical to the direction of the jet tube.

[en] Highlights: • LES method is used for simulating film cooling of a fanshaped hole. • Coherent structures for film cooling of fanshaped hole is analyzed in detail. • Time frequency analysis of fluctuation signals for film cooling of fanshaped hole is performed. - Abstract: Large eddy simulation was applied for studying interaction between hot crossflow and coolant jet from a fanshaped hole. Simulations were performed at two blowing ratios, M = 0.5 and 1.5, and the Reynolds number, Re = 45674, based on the crossflow velocity and hole diameter. Downstream of shaped hole, plenty of hairpin vortexes distribute disorderly on the flat plate, and form ‘forests of hairpin vortexes’. Roller vortexes and horseshoe vortexes are the important structures in the near filed region. Because of low jet velocity, fanshaped holes show weaker roller vortexes and horseshoe vortexes compared with round holes. In the far filed region, small-scale vortexes originating from break up of large-scale coherent structures take the dominant role. The projections of vortexes on vertical, spanwise and streamwise directions for fanshaped hole were discussed in detail. By time–frequency analysis of velocity fluctuation signals, the dominant frequency for fanshape holes is indistinct, and periodicity of film cooling of shaped holes is weaker than that of round hole.

[en] Highlights: • The 1-D method lacks the ability to differentiate cooling performance between multi-row arrangements. • The proposed 2-D method demonstrates satisfactory accuracy in predicting multi-row cooling performance. • The 2-D method is reliable in recognizing the local over-cooling or under-cooling. • The relative error is reduced from 45.64% to 19.77% by adopting the 2-D method. This work develops a new and effective method to predict the 2-D cooling effectiveness distribution. The assumption in the existing 1-D method is abandoned and replaced by a scalar diffusion equation to model the lateral spreading of the coolant. The proposed model can be used for predicting 2-D multi-row cooling performance and is validated over four arrangements of double-row cooling holes against in-house experimental data. The paper further presents the advantages of the current method over the classic 1-D method. 2-D distributions for different multi-row configurations are successfully obtained and the relative error is reduced to 19.77% as opposed to that of 45.65% with the 1-D model. The time consumption by the proposed method is on the order of $1\times 10^{-3}$ s which is exceedingly efficient for the cooling design process. To sum up, the proposed method is accurate, capable of 2-D multi-row modeling and of simple form and high efficiency. Hence it is potentially an effective tool for film cooling design.

[en] The influence of a small hole geometry variation on the jet cross flow interaction is investigated experimentally using particle image velocimetry and liquid crystal thermography. The flow characteristics correspond to film cooling in gas turbines. A production imperfection is represented with the small variation of the hole geometry. The experiments were conducted without and with the hole imperfection at three velocity ratios. If the imperfection is absent, the flow field is stable and clockwise vortices are detected downstream. The imperfection blocks the hole, accelerates the jet and changes the formation of large vortical structures. It produces the additional windward vortices, which influence the flow field and enhance the inflow of the cross-stream towards the cooled surface. The imperfection reduces the film cooling effectiveness