Spray Angle Research Articles

Numerical study on the effects of blocking ratio and spraying angle on the smoke flow characteristics of new energy vehicle fires in tunnels

Compared with traditional fuel vehicle fires, new electric vehicle fires have a fast flame propagation rate and higher smoke toxicity. Thus, higher requirements need to be implemented when designing tunnel fire protection. In this study, a horizontal highway tunnel with a rectangular cross-section is taken as the research scenario, and the FDS numerical simulation method is used to study the effects of different blocking ratios and key parameters of the water mist system in a rectangular tunnel under longitudinal ventilation on the smoke temperature and flow state near the fire source area. The results indicate that the average velocity of smoke in the vicinity of the fire source in the tunnel is mainly related to the cross-sectional size of the obstruction, and changing the spray angle does not affect the state of the smoke flow field. The relationship between the cross-sectional size of the blocked vehicles in the tunnel and the spray angle is proposed. In addition, when the blocking ratio reaches 25%, the back-layer length of smoke corresponding to the subsequent blocking ratio remains basically unchanged. Setting a reasonable spray angle can significantly reduce the CO mass fraction in the tunnel, while the visibility of the tunnel will also decrease. Using the dimensionless analysis method, a critical velocity correction model based on the blocking ratio factors is proposed. These research results provide a theoretical reference for the design of longitudinal ventilation and smoke exhaust for new energy-electric vehicles in highway tunnels.

A Simulation of Artificial Neutral Gas‐Dust Plasma in the Ionosphere

AbstractDusty plasma is generally defined as a plasma system containing a large number of nano‐ or micron‐sized dust particles. Its plasma properties and propagation properties of wave travel through it is of great scientific significance to the understanding of many fundamental problems in space physics and astrophysics. Based on previous studies on rocket exhaust and Polar Mesosphere Summer Echoes, fluid mechanics and dust microphysics are combined to simulate the ionospheric plasma structure generated by neutral gases and charged aerosols using fluid theory and kinetic theory. The Total Electron Content of the in‐situ detection beacon is simulated and compared with the experimental phenomenon given in Charged Aerosol Release Experiment by Bernhardt et al. The ray tracing algorithm is used to simulate the path deflection of the radio wave when it passes through the artificial disturbance area generated by the gas‐solid mixture, and the simulation results of ionosonde and analysis are given. Since the neutral gas expands substantially isotropically after being released, the resulting depleted structure is an approximately isotropic sphere, or an acorn‐like structure. The solid particles are constrained by the nozzle, and particles will distribute within a spray angle, and the depletion structure will appear as a “broom‐like” or “cone‐like” structure. If the size of dust particles is small enough, the particle movement will be restricted by the geomagnetic field, resulting in a “squid‐like” ionospheric structure. Because of the fishtail‐like sharp boundary, radio waves passing through it are deflected in a specific path, which is markedly different from the effect of pure neutral gas injected into the ionosphere.

Effect of piston bowl geometry and spray angle on engine performance and emissions in HCCI engine using multi‐stage injection strategy

AbstractThe homogeneous charge compression ignition (HCCI) and combustion chamber geometry play significant roles in improving the potential of compression ignition engines and their environmental sustainability. However, a major hindrance to the progress of HCCI technology has been the notable decline in brake thermal efficiency and emit high levels of hydrocarbon (HC) and carbon monoxide (CO) which is mainly due to the low temperatures during combustion and low post oxidation of these components. Combustion chambers like hemispherical combustion chamber (TCC) and toroidal combustion chamber (TCC) are known to provide better combustion characteristics due to their increased surface‐to‐volume ratio. Moreover, injection timing and spray position have shown a significant effect on the controlling onset of combustion and emission in HCCI engine. Therefore, the primary objective of this numerical study is to enhance the engine characteristics in HCCI mode using an HCC and TCC piston bowl geometry coupled with multistage injection and compare the results with flat piston bowl geometry. The results show that the toroidal shape piston geometry provides 3%–5% higher brake thermal efficiency compared to the conventional piston geometry. Additionally, the energy balance analysis revealed that the combination of modified piston geometry and multi stage injection improved the combustion process by reducing the energy losses due to incomplete combustion and heat transfer to the engine walls. These findings suggest that the proposed injection strategy combined with modified piston geometry has the potential to enhance the performance of HCCI engines and reduce their environmental impact.

Prediction of atomization characteristics of pressure swirl nozzle with different structures

The structure of the pressure swirl nozzle is an important factor affecting its spray performance. This work aims to study pressure swirl nozzles with different structures by experiment and simulation. In the experiment, 10 nozzles with different structures are designed to comprehensively cover various geometric factors. In terms of simulation, steady-state simulation with less computational complexity is used to study the flow inside the nozzle. The results show that the diameter of the inlet and outlet, the direction of the inlet, the diameter of the swirl chamber, and the height of the swirl chamber all affect the atomization performance, and the diameter of the inlet and outlet has a greater impact. It is found that under the same flow rate and pressure, the geometric differences do have a significant impact on the atomization characteristics, such as spray angle and SMD (Sauter mean diameter). Specific nozzle structures can be customized according to the actual needs. Data analysis shows that the spray angle is related to the swirl number, and the SMD is related to turbulent kinetic energy. Through data fitting, the equations for predicting the spray angle and the SMD are obtained. The error range of the fitting equation for the prediction of spray angle and SMD is within 15% and 10% respectively. The prediction is expected to be used in engineering to estimate the spray performance at the beginning of a real project.

Clotrimazole-Loaded Borneol-Based In Situ Forming Gel as Oral Sprays for Oropharyngeal Candidiasis Therapy.

Oral candidiasis encompasses fungal infections of the tongue and other oral mucosal sites with fungal overgrowth and its invasion of superficial oral tissues. Borneol was assessed in this research as the matrix-forming agent of clotrimazole-loaded in situ forming gel (ISG) comprising clove oil as the co-active agent and N-methyl pyrrolidone (NMP) as a solvent. Their physicochemical properties, including pH, density, viscosity, surface tension, contact angle, water tolerance, gel formation, and drug release/permeation, were determined. Their antimicrobial activities were tested using agar cup diffusion. The pH values of clotrimazole-loaded borneol-based ISGs were in the range of 5.59-6.61, which are close to the pH of 6.8 of saliva. Increasing the borneol content in the formulation slightly decreased the density, surface tension, water tolerance, and spray angle but increased the viscosity and gel formation. The borneol matrix formation from NMP removal promoted a significantly (p < 0.05) higher contact angle of the borneol-loaded ISGs on agarose gel and porcine buccal mucosa than those of all borneol-free solutions. Clotrimazole-loaded ISG containing 40% borneol demonstrated appropriate physicochemical properties and rapid gel formation at microscopic and macroscopic levels. In addition, it prolonged drug release with a maximum flux of 370 µg·cm-2 at 2 days. The borneol matrix generated from this ISG obsentively controlled the drug penetration through the porcine buccal membrane. Most clotrimazole amounts still remained in formulation at the donor part and then the buccal membrane and receiving medium, repectively. Therefore, the borneol matrix extended the drug release and penetration through the buccal membrane efficiently. Some accumulated clotrimazole in tissue should exhibit its potential antifugal activity against microbes invading the host tissue. The other predominant drug release into the saliva of the oral cavity should influence the pathogen of oropharyngeal candidiasis. Clotrimazole-loaded ISG demonstrated efficacious inhibition of growth against S. aureus, E. coli, C. albicans, C. krusei, C. Lusitaniae, and C. tropicalis. Consequently, the clotrimazole-loaded ISG exhibited great potential as a drug delivery system for oropharyngeal candidiasis treatment by localized spraying.

Anisotropy and macro porosity in wet sprayed concrete: Laminations, fibre orientation and macro pore properties measured by image analysis, PF test, water penetration and CT scanning

Sprayed concrete typically contains large, irregularly shaped macro pores. These are a product of the spray application and are different to spherical pores formed by an air entrainment agent for frost protection. Image analysis, capillary suction and pressurised saturation (PF test) and CT scanning were used to measure and analyse the macro porosity in specimens taken from 20 different panels sprayed in four series with varying accelerator doses, varying spraying distances and angles and varying sprayed concrete mixes. Macro porosity measurements by image analysis (3.8–7.5%) and CT scanning (4.7–10.1% measured on five specimens only) were higher than measurements by pressure saturation (2.5–4.9%). The macro porosity increased with increased set accelerator dose. 9–20% of the PF macro pore volume filled with water when submerged at atmospheric pressure. The shape of the macro pores was measured to be non-spherical, with 50% of length/width ratios greater than 1.5. The macro pores were measured to tend towards orientation parallel to the substrate. Likewise fibre orientation was measured by CT scanning to tend towards orientation towards parallel to the substrate. Water penetration tests were done on specimens with the water pressure applied parallel and perpendicular to the direction of sprayed concrete application. Water penetration was measured to be very low parallel to the direction of application, but much higher perpendicular to the direction of application, due to macro porosity and laminations in this direction, indicating the importance of execution in wet spraying of concrete.

Impact of spray angle and particle velocity in cold sprayed IN718 coatings

Cold spray (CS) deposition has potential applications in repair technology or additive manufacturing due to its ability to operate at low temperatures, achieve high deposition rates, and produce thick, dense coatings. For adoption of CS in repair applications, it is crucial to evaluate the influence of spray angles since geometry of repair zones are typically complex and non-flat. In this work, we investigated the influence of spray angles and particle velocities on the cold spray deposition of Inconel 718 (IN718) powder particles using N2 as propellant gas. Three oblique spray angles including 50, 60 and 70° were compared with the 90° normal spray angle for cold spray deposition of IN718 powders on Al6061 substrate. Three sets of cold spray parameters at each spray angle, giving particle velocities from 820 to 920 m/s were employed to study their effect on the coating properties. Particle velocity was found to have greater impact on coating porosity compared to spray angle. Coating with lowest porosity and lowest surface roughness but highest compressive surface residual stress was achieved with deposition at lowest spray angle (50°) and highest particle velocity (920 m/s). Changing the spray angle has greater influence on the deposition efficiency, with thickest coating observed at normal spray angle of 90° across all three cold spray conditions. Finite element method (FEM) simulations were also performed to understand the influence of powder and substrate temperatures on critical angles for bonding. The simulation results suggest that elevating the powder temperature is likely to cause a slight increase in the critical bonding angle.

Study on the effect of injection temperature and nozzle geometry on the flashing transition of liquid ammonia spray

Ammonia is a promising alternative fuel for carbon emission reduction in industry, transport, and power generation. For high-pressure combustion environment applications, direct injection of liquid ammonia (LNH3) is considered. Because of its thermophysical properties, and dependence on the injection and combustion environment conditions, the direct injection of ammonia in its liquid state can lead to flash-boiling, changing drastically the spray characteristics. In this study, we characterized the effect of injection temperature and nozzle geometry on the spray characteristics and transition to flashing using backlit imaging. Flow rates pressure curves and spray angles were obtained in a well-controlled environment and can be used as a database for simulation. Finally, some practical considerations on the design of nozzles are highlighted in the present work.

Experimental Study on Spray Cooling Heat Transfer of LN2 for a Large Area

Spray cooling has been considered one of the most promising thermal control methods of high-heat flux devices. Most of the spray cooling research focuses on electronic components as the main application object to achieve higher heat dissipation heat flow in ambient temperature regions for small areas. Water is the most common cooling medium. This paper investigates the application of spray cooling thermal control over large areas. In this study, the heat-transfer characteristics of liquid nitrogen (LN2) for large areas was investigated by conducting experiments. The test surface is 500 mm × 500 mm, which was cooled by a nine-nozzle array. The spray nozzles used in the experiment were conical nozzles with an orifice diameter of 1.6 mm, a spray angle of 120°, and a spray height of 42 mm. Liquid nitrogen was forcefully ejected from nozzles by the high pressure of a liquid storage tank to cool the test surface. According to the cooled surfaces, spray directions, and spray pressures, three groups of experiments were conducted. The results showed that the smooth flat surface has the best heat-transfer performance in three kinds of surface structures, which are macro surface, porous surface, and smooth flat surface. The heat-transfer coefficient varied by ±20% with different spray directions, and the surface heat-transfer coefficient increased linearly with increasing spray pressure. Most of the spray cooling research focuses on heat dissipation in the ambient temperature region for equipment over small areas. The results can benefit thermal control application in various fields. The research in this paper can provide a reference for the application of large-area spray cooling, and the application areas mainly include metal manufacturing processing cooling, aircraft skin infrared radiation characteristics modulation, and laser weapon equipment cooling.

Effect of ambient pressure on the performance of a gas-centered swirl coaxial injector

In this study, water and air were used as simulated media to investigate the spray characteristics of a gas-centered swirl coaxial (GCSC) injector under different ambient pressures through experimental, simulation, and theoretical approaches. The results showed that for the same liquid mass flow rate, the breakup length of the liquid film decreased with increasing ambient pressure, with the extent of the decrease diminishing as the ambient pressure increased. In addition, it was found that under the same ambient pressure, the larger the liquid mass flow rate, the shorter the liquid film breakup length. Moreover, for any gas–liquid mass flow ratio (GLR), the spray angle increased significantly with ambient pressure, and the liquid film suddenly expanded compared to the no-ambient pressure condition. At the same time, the breakup length of the liquid film increased. As ambient pressure increased, the spray angle increased while the breakup length decreased. When the GLR was small, self-pulsation occurred, which gradually disappeared with increasing ambient pressure. The frequency of self-pulsation decreased with increasing ambient pressure. The periodic self-pulsation of the spray was the result of the combined effects of the centrifugal force of the rotating liquid film, surface tension of the liquid film, aerodynamic force, and pressure difference inside and outside the liquid film. Overall, these findings provide insight into the spray characteristics of GCSC injectors under different ambient pressures, which can be of importance to the design and optimization of liquid rocket engines.

A nasal spray vaccination device based on Laval nozzle and its experimental test

In order to realize the application of the nasal spray vaccination in the prevention and protection of respiratory infectious diseases, a nasal spray vaccination device is designed in this paper. The device uses a Laval nozzle structure to generate a high-speed airflow that impinges on the vaccine reagent and forms nebulized particles. Through optimizing of the Laval nozzle structure and testing experiments on spray particle size, spray velocity, spray angle and spray rate, a set of parameters which is applicable to actual nasal spray vaccination is obtained. The experimental results show that when the air source pressure is 2 bar, the spray angle is about 15°, the diameter of the spray particles Dv50 is about 17 μm, the volume fraction of particles with diameter smaller than 10um is about 24%, the spray rate is close to 300 μl/s. The vaccine activity tests demonstrate that under these conditions, not only the biological activity of vaccines is guaranteed, but also the delivery efficiency is well assured.

Effect of Spray Angle on Some Physical Properties of a Ceramic System Produced by Thermal spraying Coating

The angle of thermal spraying by the flame is considered one of the important influences on the coating layer, where alumina (Al2O3)% was used as a base material, and it was reinforced with two metals (TiAl) with weight ratios of (25%) in order to produce a cermet composite material with a final thickness ranging between (300-400) µm and with a fixed thermal spray distance of 16cm, the samples resulting from the paint were thermally sintered at a temperature of (1000°C) for an hour and a half, after the samples were taken out of the oven and some mechanical operation was performed on them, some physical tests were conducted, the most important of which included an examination X-ray diffraction, as well as porosity, hardness, and adhesion strength, to show through laboratory tests that the best thermal spray angle is 90°, at a mixing ratio of 25% after thermal sintering.

Effect of Spray Angle on Some Physical Properties of a Ceramic System Produced by Thermal spraying Coating

Effect of Spray Angle on Some Physical Properties of a Ceramic System Produced by Thermal spraying Coating

A study of the temperature effect on the spray characteristics in the cone-jet mode of electrohydrodynamic atomization (EHDA) with viscous liquids

In this work, the near-field spray characteristics of electrohydrodynamic atomization (EHDA) for viscous liquids (ethanol, G20, G40, G50, G66, and glycerol) under various temperatures T (T is from 293 to 343 K), electric Bond numbers BoE (BoE is from 0 to 3.5) and dimensionless flow rate Q* (Q* is from 11 to 400) have been investigated by employing a high-speed imaging technique. The transition of the spray modes, variations of the spray angle θ1, semi-angle of Taylor cone θ2, and spraying droplet size (the Sauter mean diameter D32 and the probability density function) in the cone-jet mode have been studied experimentally. The results indicate that the stable cone-jet mode disappeared regardless of increasing BoE for working fluids with relatively higher viscosity (G50, G66, and glycerol). Nevertheless, the temperature elevation promotes the appearance of the stable cone-jet mode, e.g., G66 fluid could form the stable cone-jet as liquid temperature increases to 343 K. Moreover, the temperature plays a significant role in improving the spray angle and the semi-angle of the Taylor cone, as well as droplet size distributions. Specifically, in the case of G40 fluid, the spray angle increased from about 20.8°–23.9° at room temperature (293 K) to around 34.1°–37° at 343 K. Meanwhile, the droplet size distributions were shifting from 9.73–35.49 μm at 293 K to 4.39–23.84 μm at 343 K. The increase in temperature causes a dramatic viscosity reduction in highly viscous fluids, and the viscous dissipation during the atomization reduced substantially. As a result, more kinetic energy was retained to overcome the surface energy and thus improve the quality of the spray. In addition, the dimensionless droplet size D* in the stable cone-jet mode shows a linear scaling relationship with Q*. By introducing an Arrhenius-type equation to account for the temperature effect, a model to predict dimensionless droplet size D* under various dimensionless flow rates Q* and liquid temperatures T has been proposed. The model is in good agreement with the experimental data under the stable cone-jet mode in the EHDA for viscous fluids at a range of temperatures.

Investigation on suitable swirl ratio and spray angle of a large-bore marine diesel engine using genetic algorithm

The swirl flow and spray angle are crucial to the organization of the combustion process in marine engines. In this work, to explore the suitable swirl ratio and corresponding spray angle for large-bore marine diesel engines, the artificial neural network (ANN) coupled with the genetic algorithm (GA) was used. At the same time, to increase the swirl ratio without affecting the scavenging efficiency, the cylinder gas recirculation (CGR) strategy was adopted in this manuscript. Compared with the original design, results indicate that the optimal swirl ratio is about 10 for the large-bore marine diesel engine when applying the CGR strategy. Due to the improved fuel–air mixing process and combustion process, the thermal efficiency and the output power of the optimal case increased by 4.86% and 5.2%, respectively. The present results are helpful for the design and optimization of the fuel–air mixing and combustion processes for large-bore marine diesel engines.

Effect of flow number of pilot-stage centrifugal atomizer on idle performance of internally staged combustor

Idle performance is critical to the combustion stability of internally staged combustors. Five pilot-stage atomizers are compared in an internally staged combustor, and the effects of the flow number (FN) on the combustion characteristics and emissions are investigated under idle conditions. Experimental results show that the maximum outlet temperature is 1.02–1.04 times the average outlet temperature, and the maximum temperature is located at the dimensionless radial location of 0.66. The key influencing mechanism of the temperature distribution lies in the matching between the spray angle of the pilot-stage atomizer and the angle of the recirculation zone. When the flow number (FN) of the pilot-stage atomizers was increased from 1.6 to 10, the combustion efficiency (η) showed a “decrease-increase-decrease” trend, whereas the emission of unburned hydrocarbon (UHC) showed a opposite trend. At the meantime, the emission of CO remained unchanged, and NOx remained at the undetectable level. In addition, the low sensitivity of pressure loss (3.3%-4%) and combustion stability (0.66%-0.85%) to idle conditions is attributed to the influence of combustion efficiency and outlet temperature. After a comprehensive evaluation, it is determined that an intermediate FN of 5.0 possesses the most balanced combustion characteristics and emissions under idle conditions in the pilot-stage atomizer.

Numerical simulation on gas-droplet flow characteristics and spray evaporation process in CFB-FGD tower

Nozzle arrangement in the nozzle spray system has a significant impact on the gas-droplet flow characteristics and the temperature distribution within the circulating fluidized bed flue gas desulphurization (CFB-FGD) tower, which is critical to the SO2 removal efficiency. The effects of spray direction, nozzle number and nozzle spray angle on gas-droplet distribution and temperature distribution inside the FGD tower are investigated with numerical simulation based on a Eulerian-Lagrangian mathematical model. An optimal nozzle arrangement scheme is proposed to improve the contact between gas and water droplets and the flue gas temperature distribution. Results show that upward spray direction is beneficial to the interaction between water droplets, improving gas-droplet flow characteristics and spray evaporation process, and water droplets number trapped by tower wall could be reduced in the water droplets evaporation. With the increase in nozzle number, it is conducive to the contact between flue gas and water droplets to increase the evaporation efficiency of water droplets, as well as the uniformity of temperature distribution inside the tower. With nozzle spray angle increases from 30° to 120°, flue gas velocity decreases, water droplets number trapped by the tower wall increases. The temperature distribution at different cross-section is the most uniform when the nozzle spray angle is 60°.

A Study on Dust-Control Technology Used for Large Mining Heights Based on the Optimization Design of a Tracking Spray Nozzle

Intense cutting-induced dust production in fully mechanized mining faces (FMMFs) with large mining heights produces a high amount of dust that is difficult to capture and severely affects the working environment, threatening the health of occupational staff. The effective spray range and atomization performance of tracking sprays are counteracted by the influences of the mine’s height and ventilation airflow in FMMFs. Thus, optimizing the spray’s parameters and relationship between the effective spray range and atomization performance to reduce dust levels is the main priority of dust-control techniques. In this study, a new swirl-core atomization nozzle is developed based on fluid mechanics and the solid–liquid coalescence mechanism. The liquid generates a circumferential velocity when passing through the swirl core, which considerably increases the droplet breaking power and reduces the droplet cohesion factor, achieving a remarkable atomization effect. The spray angle of the new nozzle is 57°, which is 80.9% greater than the GZPW-16 mine-use nozzle (31.5°); the effective spray range increases from 5.2 to 5.9 m; and the spray’s mist saturation is significantly better than the GZPW-16 mine-use nozzle. Under different test pressures, the particle size range of the droplets produced by the new nozzle and dust particles on site satisfied the best synergy of droplet–dust coalescence. The total and respirable dust-reduction rates were 78% and 75.1%, respectively, which were 42% and 65% higher than those of the original nozzle. The new nozzle effectively improves the efficiency of the single dust-control technique of the tracking spray, which is significant for the dust-prevention and -control technology of FMMFs with large mining heights.

Simulation on a new reverse circulation fishing tool: Design and evaluation of the salvage capacity and efficiency

AbstractTo solve the insufficient energy for reverse circulation fishing tools in complex structure wells, it is necessary to further optimize the design of the tools to improve the impurity salvage efficiency. In this work, a three‐dimensional (3D) flow field simulation model of reverse circulation fishing tool with venturi negative pressure is employed to identify the vortex zone of circulation channel and to investigate the negative pressure and jet velocity distribution around the spray nozzle based on the ANSYS‐CFX. The effects of the spray angle, diameter of the suction nozzle, and the nonstructural parameters on negative pressure and jet velocity are investigated through sensitivity analysis. As revealed from the results, there may be an optimum value for the spray angle, and the nozzle jet direction can indeed affect the propagation and attenuation of the bottom hole flow field greatly. The combination of the inner diameter of the nozzle outlet and that of the nozzle inlet (Φ + Φ′ = 3 mm + 6 mm) is the best design solution when the negative pressure at the nozzle outlet can be the highest. The negative pressure and jet velocity increase with the increasement of the inlet flow rate. The comparative analysis of different bottom hole impurity mass in the cases of the borehole inner diameter 5′ and 8.5″ on the salvage efficiency are conducted numerically. It is observed that the impurity mass salvaged and salvage time are not directly related to its total amount, but only related to the flow rate of the sucked fluid flow. The impurity salvage efficiency can be as high as 95.4%, which meets the engineering requirements in the field. This work improves the working performance of the reverse circulation fishing tool and provides theoretical guidance for well washing.

Correlation of single-phase convective heat transfer on spray cooled plain surfaces with high Prandtl number liquids

Spray cooling with transmission oils is an innovative cooling concept for electrical machines, whereby the coolant wets the end windings directly. The thermal design process of such machines requires reliable correlations of the heat transfer coefficients obtainable. Thereby, the majority of the literature only focuses on low Prandtl number coolants at ideal nozzle distances. The transferability of the existing heat transfer models to highly viscous coolants above and below the optimal nozzle distance has yet to be investigated. Therefore, the heat transfer coefficients of spray cooling on plain surfaces with aqueous glycerol solutions (model fluid) and a transmission oil of type ATF VI was investigated. The model fluid serves the purpose of covering the entire range of material properties of commercial transmission oils with only one liquid. Prandtl numbers ranging from 80 to 340 were investigated. Various cases of spray coverage were researched by varying the nozzle distance (2mm−100mm), the spray angle (20∘−80∘) and the size of the spray cooled surface (6.35×6.35mm2;12.7×12.7mm2). Regarding the case of the optimal nozzle distance, where the spray impact area just inscribes the cooled surface, the experimental data was validated with models from the literature. Large deviations of up to 450% resulted at nozzle distances above and below the optimum. Therefore, a dimensionless correlation of the heat transfer coefficient is proposed which includes all cases of spray coverage investigated, exceeding the applicability range of the existing models. The model describes the experimental data with a mean absolute percentage error of 15%.