Nozzle Combination Research Articles

Экспериментальное исследование процессов тушения модельных очагов пожара распре-деленными во времени и пространстве капельными потоками воды

In this paper the main attention is paid to a problem of increase of efficiency of major forest fires suppression. The main popular way of wildfires extinguishing - local dumping of water with use of aircraft was considered. The approach providing suppression of the fires by the distributed in time and space water flows is offered. When carrying out researches the model fire seats corresponds (in temperature and height of a flame) to ground and crown forest fires were used. For model fire seats production the pine whetstones and the typical forest combustible materials making a basis of a forest laying are used. As means of suppression the spray nozzles generating a polydisperse droplet flow with droplet radius of 0.02-0.35 mm were applied. For continuous movement of nozzles over the model fire the special system was used. The system consisted of a set of coordinate mechanisms with adjustable parameters - acceleration and speed of movement. Various ways of water spraying in a fire zone are considered. With using of the model fires (ground and crown forest fires) use of various combinations the spraying nozzles is tested. With use of high-¬speed video registration equipment and panoramic optical methods of flows diagnostics such as PIV and SP, the optimum parameters of dispersion (relative positioning and combinations of spray nozzles) providing smallest times of suppression of the model fire seat and the minimum volumes of the water spent for suppression of a flame are revealed. For the model fire seats corresponding to ground forest fire, the mini¬mum times of suppression were 45 sec, volumes of the spent water - 0.03 l, for the model fire seats corresponding to crown forest fire - 110 sec and 0.135 l. The sizes of sprayed water droplets corresponding to each scheme of dispersion necessary for effective fire extinguishing are determined. For the model fire seats corresponding to ground and crown forest fires these ranges were 0.02-0.25 and 0.08-0.35 mm, respectively. The expediency of the use of such systems in the liquidation of fires in rooms is proved.

Effect of Nozzle Spacing on Nitrogen-Oxide Emissions and Lean Operability

Nitrous-oxide emissions and the equivalence ratio resulting in lean extinction of two adjacent gas turbine fuel/air nozzles are measured as the spacing between the two nozzles is varied. Two swirl-stabilized nozzle types are tested: a high-stability pilot design, and a low-emission design with a much lower swirl number. Jet A is used as the fuel. The lean blowout point is tested for both nozzle types at each spacing. Increased spacing results in blowout at a lower equivalence ratio, which is likely due to increased air velocity between the nozzles that occurs at closer spacings. The spacing has a dramatic effect on the nitrous-oxide emissions index (grams of nitrous-oxide produced per kilogram of fuel burned) for the three possible nozzle combinations. The nitrous-oxide index emissions are greatest when two nozzles are placed close, and they decrease as the internozzle distance grows. The excited hydroxyl radical (OH)* chemiluminescence imaging shows how the OH* intensity is greater on the side of the nozzles toward the neighboring flame. This is an indication that the heat release rate and/or temperature is raised in part of the flame due to the adjacent nozzle. The magnitude of the effects of nozzle spacing, both on emissions and lean blowout, are dependent on the nozzle design. Asymmetries in the flow and flame structure of the two nozzles appear when using two high-swirl pilot nozzles at larger nozzle spacings. This disturbs the emissions trend and causes an increase in nitrous-oxide production for this case.

Water distribution from medium-size sprinkler in solid set sprinkler systems

ABSTRACT The study aimed to evaluate the water distribution from a medium-size sprinkler working in solid set sprinkler systems. Water distribution radial curves from the sprinkler operating under four nozzle diameter combinations (4.0 x 4.6; 5.0 x 4.6; 6.2 x 4.6 and; 7.1 x 4.6 mm) and four working pressures (196; 245; 294 and 343 kPa) were evaluated on the sprinkler test bench of the State University of Maringá, in Cidade Gaúcha, Paraná, Brazil. The sixteen water distribution curves were normalized and subjected to clustering analysis (K-Means algorithm), identifying the occurrence of normalized distribution curves with three different geometric shapes. A computer algorithm, in Visual Basic for Applications in Excel spreadsheet, was developed to simulate the water application uniformity (Christiansen's Coefficient - CU) from the sprinklers working with rectangular and triangular layouts in solid set sprinkler systems. For the three geometric shapes of the normalized water distribution curves, digital simulation results of water distribution uniformity for the sprinklers on mainline and lateral line spaced between 10 to 100% of wetted diameter indicated that sprinkler spacings around 50% of the wetted diameter provide acceptable CU values.

The Effects of Strainer Types on Flow Characteristics of Anti-Drift

This study investigated the effects of four different strainer types on flow characteristics (orifice coefficient (k), exponent coefficient (n), individual flow rate deviation (φ) and discharge coefficient (Cd)) of different nozzle types. The volumetric flow rates of anti-drift (AD) and multi-range (LU) flat-fan nozzles of three different orifice sizes were determined at different operational pressures (1.5, 3.0, 4.0, 6.0 and 8.0 bars). In each treatment, the nozzles were used together with cup screen strainer of 50-mesh, slotted strainer, cylindrical strainers of 40-, 50-, and 80-meshes, and ball-check strainers of 50- and 80-meshes. The flow rate measurements were also obtained without strainers. The relation between the flow rate (Q) and spray pressure (P) for each nozzle combination (nozzle type, strainer type, and orifice size) was presented using the power regression model . The “k” coefficient, which is the slope of the line referring to the relation between the nozzle flow rate and spray pressure, was evaluated as a comparison parameter between the nozzle combinations. The “k” mean values of the nozzle types using with ball-check strainers were lower than those of the without strainer, cup screen, slotted and cylindrical strainers. This result showed that the volumetric flow rate decreased with respect to the other nozzle combinations operated at the same operational pressure. Thus, the deviation rate from the nominal flow rate of the nozzles used with the ball-check strainers exceeded the acceptable deviation limit of ±10%. As the “n” coefficients of the LU and AD nozzles used with cup screen, slotted, cylindrical strainers and without strainers were close to 0.50, the ball-check strainers resulted in increasing the “n” coefficient of the nozzles. The “n” coefficient of the nozzles used with the ball-check strainers of 50- and 80- meshes was determined as 0.586 and 0.608 for the AD nozzle, respectively and, 0.576 and 0.584 for the LU nozzle, respectively. The ball-check strainers dramatically decreased the discharge coefficient (Cd) of the nozzles compared to the other strainers and the usage without strainer. For the cup screen, slotted, cylindrical strainers and the usage without strainer, the Cd means ranged from 0.67 to 0.77 for the AD nozzle, and 0.91 to 0.94 for the LU nozzle. The Cd means of the nozzles used with the ball-check strainers of 50- and 80- meshes were determined as 0.39 and 0.34 for the AD nozzle, respectively, and 0.56 and 0.53 for the LU nozzle, respectively.

Influence of Droplet Size on Efficacy of the Formulated Products Engenia™, Roundup PowerMax®, and Liberty®

As auxin-type herbicide-resistant crops become commercially available, nozzle selection will become a highly important variable for maintaining efficacy of herbicide solutions while minimizing off-target movement. Field experiments were conducted in 2013 and 2014 in Keiser, AR, to evaluate interactions among theN,N-bis-(aminopropyl)methylamine form of dicamba formulated as Engenia™, the potassium salt of glyphosate formulated as Roundup PowerMax®, and glufosinate formulated as Liberty®applied with three different nozzle types. Three TeeJet nozzles with an 11004 orifice (Turbo TeeJet [TT], Air Induction Extended Range [AIXR], and Turbo TeeJet Induction [TTI]) were used. To supplement the field data, droplet spectra for each nozzle and tank mixture combination were determined at the West Central Research and Extension Center in North Platte, NE. For most herbicide treatments and nozzle combinations, Palmer amaranth control 4 wk after treatment was > 95% both years. In 2013, TT nozzles provided 96% control of barnyardgrass and TTI nozzles provided 89% control, averaged across herbicides, except for Engenia alone. A similar effect of nozzle selection was observed in 2014. When treatments were applied to 20-cm-tall barnyardgrass in 2014, compared with 8-cm-tall plants in 2013, an antagonistic effect was observed when Engenia was tank-mixed with Roundup PowerMax. The weed control data correlated with the droplet spectrum analysis such that as volume median diameter (Dv50) increased from TT nozzles to the TTI nozzles, efficacy decreased for most tank mixtures. Results from the droplet analysis showed thatDv50relative to water decreased for Liberty alone and not when tank-mixed with Engenia or Roundup PowerMax. These results suggest that nozzle selection will play a key role in maximizing efficacy of POST applications in dicamba-resistant crops. Additionally, evaluating droplet spectra of potential dicamba-containing tank mixtures is critical for producing desired droplet size to minimize off-target movement.

Artificial neural network model for simulation of water distribution in sprinkle irrigation

ABSTRACTDetermining uniformity coefficients of sprinkle irrigation systems, in general, depends on field trials, which require time and financial resources. One alternative to reduce time and expense is the use of simulations. The objective of this study was to develop an artificial neural network (ANN) to simulate sprinkler precipitation, using the values of operating pressure, wind speed, wind direction and sprinkler nozzle diameter as the input parameters. Field trials were performed with one sprinkler operating in a grid of 16 x 16, collectors with spacing of 1.5 m and different combinations of nozzles, pressures, and wind conditions. The ANN model showed good results in the simulation of precipitation, with Spearman's correlation coefficient (rs) ranging from 0.92 to 0.97 and Willmott agreement index (d) from 0.950 to 0.991, between the observed and simulated values for ten analysed trials. The ANN model shows promise in the simulation of precipitation in sprinkle irrigation systems.

Auto-ejection of liquid drops from capillary tubes

AbstractWicking flow inside capillary tubes can attain considerable momentum so as to produce a liquid jet at the end of the tube. Auto-ejection refers to the formation of droplets at the tip of such a jet. Experimental observations suggest that a tapering nozzle at the end of the capillary tube is necessary for auto-ejection; it has never been reported for a straight tube. Besides, most experimental realizations require microgravity, although it is possible under normal gravity if the nozzle has a sufficiently sharp contraction. This computational study focuses on two related issues: the critical condition for auto-ejection, and the hydrodynamics of the liquid meniscus as affected by geometric parameters. We adopt a diffuse-interface Cahn–Hilliard model for the moving contact line, and allow the dynamic contact angle to deviate from the static one through wall energy relaxation. From analyzing the dynamics of the meniscus in the straight tube and the nozzle, we establish a critical condition for the onset of auto-ejection based on a Weber number defined at the exit of the nozzle and an effective length that encompasses the geometric features of the tube–nozzle combination. In particular, this shows that capillary ejection is not possible in straight tubes. With steeper contraction in the nozzle, we predict two additional regimes of interfacial rupture: rapid ejection of multiple droplets and air bubble entrapment. The numerical results are in general agreement with available experiments.

The application of high pressure jetting drilling in Eastern Sichuan

Based on the problem of the low rate of penetration (ROP) of well sections above Xujiahe formation (mainly sandstone and mudstone) in Eastern Sichuan, Southwest of China, this paper discusses the feasibility of a high pressure jetting drilling scheme in this area and analyses its mechanism of increasing ROP. The paper establishes a physical model of borehole flow path at bottom hole and applied the numerical simulation method to simulate the bottom hole flow field under high pressure jetting circumstance. Reasonable hydraulic parameters are recommended after analysing the influence of pump pressure, flow rate and nozzle combination on bottom hole flow field. According to the simulation results, high pressure jetting drilling tests were performed successfully in this area. The statistical results have demonstrated that high pressure jetting drilling could significantly improve the ROP of well sections above Xujiahe formation in Eastern Sichuan. [Received: May 7, 2013; Accepted: October 1, 2013]

Optimal Design of the Flow Field of Bi-center Bit

Bottom-hole flow field is determined by the hydraulic structure of PDC bit, it is one of the important factors that affect the performance of the bit. The flow field optimizing is an important means of improving the hydraulic performance of drill bit. Because of the complicated structure, the performance of bi-center bit is different from conventional bit, thus its flow field is necessary to be optimized. In this paper, an evaluation method of the bottom-hole flow field of the bi-center bit is proposed, the relationships between flow distribution, nozzle angle and cuttings carrying effect are studied with numerical simulation method, the reflux distributions of the bottom-hole flow field are obtained under the different combinations of different size nozzles and nozzle spray angles, the hydraulic structure of the bit is optimized according to the numerical simulation results, then an optimal hydraulic structure of bi-center bit is obtained

Study and Application on Hydrajet Multistage Fracturing Technology

Hydrajet fracturing has the advantages which not only include perforating without compacted zone, creating fracture exactly, but also include controlling fracture height, shortening the working cycle, reducing operation risk and etc.[. Through studying the optimization of nozzle materials and combination, string structure, operation pressure of surface casing and annular displacement, the hydraulic jet multistage fracturing technology is formed. This technology is successfully used and proves it has good popularization and application.

IDENTIFICATION OF TWO-DIMENSIONAL VOID PROFILE IN A LARGE SLAB GEOMETRY USING AN IMPEDANCE MEASUREMENT METHOD

Multi-dimensional two-phase phenomena occur in many industrial applications, particularly in a nuclear reactor during steady operation or a transient period. Appropriate modeling of complicated behavior induced by a multi-dimensional flow is important for the reactor safety analysis results. SPACE, a safety analysis code for thermal hydraulic systems which is currently being developed, was designed to have the capacity of multi-dimensional two-phase thermo-dynamic phenomena induced in the various phases of a nuclear system. To validate the performance of SPACE, a two-dimensional two-phase flow test was performed with slab geometry of the test section having a scale of 1.43 m × 1.43 m × 0.11 m. The test section has three inlet and three outlet nozzles on the bottom and top gap walls, respectively, and two outlet nozzles installed directly on the surface of the slab. Various kinds of two-dimensional air/water flows were simulated by selecting combinations of the inlet and outlet nozzles. In this study, two-dimensional two-phase void fraction profiles were quantified by measuring the local gap impedance at 225 points. The flow conditions cover various flow regimes by controlling the flow rate at the inlet boundary. For each selected inlet and outlet nozzle combination, the water flow rate ranged from 2 to 20 kg/s, and the air flow rate ranged from 2.0 to 20 g/s, which corresponds to 0.4 to 4 m/s and 0.2 to 2.3 m/s of the superficial liquid and gas velocities based on the inlet port area, respectively.

Air-assisted sprayer adapted for precision horticulture: Spray patterns and deposition assessments in small-sized citrus canopies

An axial-fan air-assisted sprayer, adapted with variable rate nozzles and adjustable air-assist flow control, for citrus tree-specific precision spraying, was tested. Static experiments were conducted to determine spray patterns at varied nozzle flow rates and air-assistance settings. Spray patterns confirmed that the sprayer delivered variable liquid flow rates and the air-diverting louvre controlled the air-assistance providing targeted spray delivery. Field experiments were conducted to determine suitable air-assistance and nozzle combinations needed in the future for sensor-controlled spraying in young (small-sized) citrus canopies. Experiments involved two nozzle treatments, a) nozzles 1–6, and b) nozzles 2–3 at 100% output rates and three (40%, 70%, and 100%) levels of air assistance selected based on spray patterns. The sprayer was operated at a travel speed of 4.5 km h−1 and the water-soluble tracer deposition on biological and artificial targets, at 0.6 m and 1.4 m above ground and laterally at the canopy front, middle, and back, respectively were measured using fluorimetry. Results suggested that within nozzles 1–6 treatments with varied air-assist, 70% air-assistance was more effective for small sized canopies than 100% air-assistance; it appeared that the latter propelled the spray beyond the canopy and reduced the spray deposition efficiency. Also, for the citrus canopies studied, the use of two or three nozzles instead of the lower six nozzles (i.e. the control treatment) might be more suitable since they would result in 50% or less chemical usage while having comparable spray deposition to that of the control.

Numerical and Experimental Studies on the Supersonic Coaxial Jet Mixing

Coaxial nozzles are an integral part of many engineering systems where mixing of different fluid streams is required. Single noncircular nozzles have been shown to have better mixing characteristics than their axisymmetric counterparts. Therefore, a combination of such nozzles into coaxial configurations is promising. The aim of the present study is to quantitatively determine the effects of the geometry of the primary supersonic jet on the mixing characteristics with the secondary high speed subsonic jet. Measurements of pressure profiles at several positions along central axis of jets using identical facilities and nominally identical experimental conditions were done. The mixing is dominated by the vortex structures that are present in the inner shear layers. The interaction of the vortex structures govern the growth, and entrainment, and mixing of the jet. Also, the experimental results show that the radial and centerline pressure profiles through various coaxial jets has good correlation with the CFD simulation.

Drilling characteristics of combinations of different high pressure jet nozzles

The high speed fluid jet for directly or indirectly breaking rock is one of the most effective ways to improve the deep penetration rate. In order to maximize the efficiency of energy use, the flow characteristics of different combinations of high pressure jet nozzles are analyzed through numerical simulations. According to the velocity vectors at the bottom and the bottom hole pressure diagram, the effects of the high pressure nozzle combinations on the flow structure and the penetration rate are analyzed. It is shown that the combination of three vertical edge nozzles is very efficient, but inefficient in cleaning the bottom hole and eroding the wall. The jet velocity is 400 m/s and the radius is 5 mm, with a center nozzle added, the problem can be solved, but the high-pressure fluid displacement would increase. The center nozzle's jet velocity is 200 m/s and the radius is 8 mm, the combination of two vertical edge nozzles and a center tilt nozzle or that of a vertical edge nozzle and a center tilt nozzle would provide a flow structure favorable for drilling. The angle of inclination is 10°. To take advantage of high pressure jet energy to improve the efficiency of drilling, it is important to select a suitable nozzle combination according real conditions.

Evaluation of the spray stability on liquid injection in gas–solid fluidized beds by passive vibrometric methods

AbstractFor some operations, such as fluid coking, gas atomised liquid feed must be injected via spray nozzles into gas–solid fluidized beds. A stable or non‐pulsating spray with a controlled droplet size is desired. The spray stability of various gas–liquid pre‐mixer and nozzle combinations was determined in open air conditions through analysis of vibration measurements on the upstream conduit with an accelerometer correlated to physical downstream spray measurements. The open air vibration measurements did not correspond to vibration measurements while spraying into a fluidized bed due to external vibrations from the fluidisation. The vibration measurements, however, can provide a relative ranking of spray stability of various gas–solid pre‐mixer and nozzle combinations for similar fluidisation conditions. In addition, the gas to liquid ratio (GLR) and the gas properties were all found to affect spray stability.

EVALUATION OF SPRAY DISTRIBUTION FOR LOW PRESSURE EMTF NOZZLES

The full automatic patternometer was used with ultrasonic sensor and compatible software program to measure the spray distribution from different EMTF nozzles under conditions of JKI laboratory in Germany. The goals of present study are measured spray distribution of the EMTF nozzles using the full automatic patternometer single nozzle test, by comparing the distribution profiles of sprays from EMTF nozzles those from standard fan nozzles. As well as investigating to find the optimum combination for EMTF nozzles from the available nozzles in the marketing which may be produced a good uniformity spray distribution. The current investigation research was cared out in the Federal Biological Research Centre for Agriculture and Forestry (JKI), Braunschweig, Germany. The full automatic patternometer was adapted at the optimum air conditions, 20° C air temperature and 80 % relative humidity. Eight external mixing twin fluid nozzles were evaluated in a patternometer single nozzle test to compare spray distribution. Each tip was compared at 60 kPa liquid pressure, parallel to a 150 kPa and 200 kPa air pressure for each. Two levels for nozzle height 50 cm and 70 cm, and co-angling 45° and 60° was treated and studied their effect with the interaction of both nozzles and air pressure on coefficient of variation percent. The results indicated that the minimum CV % values for good spray distribution were 10.6 %, 12.9 % and 14.0 % for EMTF nozzle N8, N3 and N7 at 50 cm nozzle height, 45° co-angling and 200 air pressure respectively. The EMTF nozzle N8 produced the CV % nearly the standard ISO nozzle CV percentages values. The uniformity spray distribution CV percent values for N8 (Lechler FT 5–608 & DG800-04 VK) nozzle at the optimum co-angling 45°were 11.0 % and 12.1% at 50 cm and 70 cm nozzle height respectively. As well as, there are non effects of the interaction of air pressures with the all factors on the CV percentage. It may therefore be concluded that the CV % values are more strongly dependant on the combinations of nozzles in the EMTF nozzles, which is highly significant in data.

Effect of irrigation uniformity on evapotranspiration and onion yield

SUMMARYThe main objective of the current study was to analyse how water application through a sprinkler irrigation system influences yield of onion (Allium cepaL.), taking into account water application heterogeneity and the effects on theoretical crop evapotranspiration (ETc). Field experiments were conducted on commercial onion plots, irrigated with a permanent sprinkler irrigation system, located in Albacete, Spain, over two irrigation seasons. Two experimental plots were selected each study year: plot A (PA), in which water was applied heterogeneously by using sprinklers with different nozzle combinations, and plot B (PB, used as the reference plot) in which the four sprinklers were maintained with the same nozzle combinations. Both experimental plots were divided into 25 subplots with the aim of studying the water distribution (measured as Christiansen uniformity coefficient (CU)), the impact on the actual evapotranspiration (ETa) and the yield obtained. Irrigation was scheduled using a daily simplified water balance method within the root area following the approach of the Food and Agriculture Organization. In the present study, sprinkler irrigation in PAresulted in lower CU (65–82% lower in 2002 and 59–79% lower in 2005) compared with PB(78–92% lower in 2002 and 79–93% lower in 2005). Between 30 May and 18 August 2002, the estimated crop water requirements in PAin the absence of water deficit was 22 mm over the accumulated value of ETc (491v.469 mm), while estimated crop water requirements under water deficit were 187 mm below ETc (282v.469 mm). In 2005, between 29 May and 25 August, ETa without water deficit was more similar to ETc (458v.444 mm) but Eta under water deficit was 242 mm. The greater uniformity of water distribution in PBwas translated into a greater uniformity of yield distribution. A smaller range in yield was observed in PBwhen compared with PA. No statistically significant differences were observed between PAand PBin the crop quality parameters bulb moisture content, total soluble solids, pH and total acidity.

COMPERASION STUDY ON LOW PRESSURE EMTF NOZZLES BASED ON DROPLETS SIZE CHARACTERISTICS

The current study carried out in the Federal Biological Research Centre for Agriculture and Forestry (JKI) Braunschweig, Germany. The goals of this research were to measure the droplet size for the developing external mixing twin fluid nozzles (EMTF) that will target and spray the pesticide, especially biological and herbicides pesticides. As well as investigating to find the optimum combinations of the EMTF nozzles from the available nozzles that applied in the field of agriculture. Also the reduction of the water volume rate is an important aspect in the current research to reduce application costs. The tongue nozzle (Lechler FT5-608) for the air and the eight different nozzles from Lechler and Tee Jet for the liquid nozzle were selected to obtain the combinations of EMTF nozzles. Oxford lasers “VisiSizer” system PDIA was used to test and measured the droplets size from different EMTF nozzles. The two levels of air pressures 150 (1.5 bar) and 200 kPa (2 bar) at liquid pressures 30 (0.3 bar) and 60 kPa (0.6 bar) and two co/angling (injection angles) 60° and 45° were tried to study their effect on droplets size, as well as to find the optimum EMTF nozzle configuration. It was found that the external mixing twin fluid could be producing the different droplet spectrum from medium to very fine droplet at low liquid pressure. The external mixing twin fluid nozzle combination N1 (TT11003+ Lechler FT 5 - 608) produce the medium spectrum compared to the N2, N2, N3, N4, N5, N6, N7 and N8 EMTF nozzles combinations. The spray characteristics droplets size Dv0.1, Dv0.5 and Dv0.9 for N1 EMTF nozzle are 95.2 µm, 226.6 µm, and 486.3 µm at 150 kPa (1.5 bar) air pressures; and 77.2 µm, 171.2 µm, and 450 µm at 200 kPa (2 bar) air pressures respectively. On the other hand, the N5 (Lechler LU 120-015 POM +Lechler FT 5 – 608) nozzle produce the fine spectrum at the above air and liquid pressure conditions. As well as the result indicated that the external mixing twin fluid could be reducing the water volume rate. The increase of liquid pressure tends to decrease of the droplet size spectra. By changing the injection angle may able to produce the finest droplet without any increasing of the applied costs. Also it is able to use the widely available agricultural nozzles to make the external mixing twin fluid which are working at low spray pressure.

Flow impinging onto a conical cavity: A conical and annular nozzle combination

Flow emanating from a combined conical and annular nozzle and impinging onto a conical cavity is considered. Two cone angles of the nozzle and two cavity depths are simulated for flow field around the nozzle and the cavity as well as for the heat transfer rates from the cavity surface. The conical cavity wall is assumed at 1500 K to resemble a laser-heated cavity and air is used as a working fluid. The Reynolds stress turbulence model is incorporated to account for the turbulence. It is found that the Nusselt number along the cavity surface is influenced by the cavity depth. The Nusselt number attains high values in the region close to the cavity edge. The wall shear stress at the cavity edge is influenced by the nozzle cone angle such that the shear stress increases for the nozzle cone angle of 70° in this region over values for the cone angle of 55°.

Flow emerging from annular-conical nozzle combinations and impinging onto a cylindrical cavity

Flow emerging from a combination of annular and conical nozzles and impinging onto a cylindrical cavity at elevated all temperature is considered, and the flow field and heat transfer rates from the cavity are computed. In the simulations, two cavity depths and four average jet velocities at nozzle exit are accommodated. Reynolds Stress Turbulence model is introduced to account for the turbulence. Air is used as working fluid while steel is considered as the cavity material. It is found that the Nusselt number attains high values in the neighborhood of the stagnation zone at the cavity bottom surface, which is more pronounced for 1 mm depth cavity.