Turbulent Air Research Articles

Broadening of cloud droplet spectra through eddy hopping: Why did we all have it wrong?

Abstract In situ aircraft observations in adiabatic and close-to-adiabatic cloudy volumes suggest that cloud droplet spectra are often broader than predicted by growth of a droplet population rising from the cloud base. Cloud turbulence has been suggested as one of possible mechanisms for the observed spectral broadening. This paper reviews computational studies of the impact of cloud turbulence on the diffusional growth of cloud droplets in adiabatic cloudy volumes. These studies typically apply direct numerical simulation (DNS) or scaledup DNS approach to represent diffusional growth of cloud droplets embedded within homogeneous isotropic air turbulence. There is also a theory that predicts that the droplet spectral width continuously increases in time because of the individual droplet growth or evaporation within turbulent eddies. This mechanism has been referred to as eddy hopping. This paper expands the discussion in Prabhakaran et al. (J. Atmos. Sci. 2022) and illustrates the fundamental flaw of past computational and theoretical studies. These studies do not consider vertical dispersion of droplet positions that leads to growth of droplets that in the mean move upwards, and to evaporation of those that move downwards. The theoretical prediction comes from confusing spectral broadening with the vertical dispersion of droplet positions when periodic lateral boundaries are used in DNS. Computational examples using a stochastic model mimicking eddy hopping show that droplet spectral width does not continuously increase in time, but it saturates at a small spread. Methodologies for appropriate numerical studies of the adiabatic spectral width evolution in natural clouds are discussed.

Impacts of Changing Atmospheric Circulation Patterns on Aviation Turbulence Over Europe

AbstractAddressing aviation turbulence not only enhances passenger comfort but also help to reduce fuel consumption and environmental impact, supporting aviation sustainability. By using ERA5 reanalysis data we explore how changing atmospheric circulation, monitored via sea level pressure trends, impacts aviation turbulence over Europe. Our results show coherent climate anomalies, with rising turbulence intensity over the UK and Northern Europe where most events involve clear air turbulence, which occurs unexpectedly and without warning, particularly at flight altitudes. We also highlight a clear seasonal patterns in moderate‐or‐greater turbulence encounters, most frequent and intense in winter, with a key role of wind shears due to the sub‐tropical jet position over Southern Mediterranean. Our approach adds to previous studies on the same topic by analyzing individual atmospheric circulation pattern changes and their effects on turbulence‐related factors. This offers insight into how climate change affecting atmospheric dynamics may contribute to increased aviation turbulence.

Detection of production relevant deviations in paint sprays

AbstractSpray painting is still a poorly manageable process due to the complex interaction of physical, chemical and environmental influences like turbulent air flows, strong electrostatic fields, complex viscosity of paints and paint booth conditions. Consequently, many important properties of the painted film, like thickness, color, surface structure and the efficiency of the process are not controllable in an adequate manner, despite the enormous economic ramifications of poor quality control in high volume applications, such as in the automotive industry. This study shows how novel, online spray monitoring can instantaneously generate characterizing quantities from the spray to detect harmful deviations in the process. In this study, several minute changes have been experimentally imposed on a paint system, such as changed paint viscosity or pigmentation, deviations in air flow and paint flow rates, and defective or used and worn equipment parts. It will be shown that all these deviations lead to features which allow a clear distinction from the intact and reference cases. Additionally, it is shown that most of the deviations, if not detected, would have led to quality issues of the paint coating.

Atmospheric Turbulence Parameters Deduced from VerticalProfile of Cn2

The proposed framework can capture realistic spatiotemporal variations in atmospheric turbulence parameters based on local meteorological conditions, such as Fried's parameter r0, isoplanatic angles θ0, seeing ε, scintillation rate , and the wavefront coherence time τ0. Those parameters have been deduced from the refractive index structure parameter Two Iraqi locations were compared, specifically the middle and southern borders, and atmospheric turbulence parameters relevant to astronomical observation were measured, lines were drawn at latitudes 34.26° and 28.31°, respectively. The methodology included collecting meteorological data from both sites and performing numerical simulations based on atmospheric turbulence parameters. According to the criteria of air turbulence, the results showed that the middle of Iraq was better than the southern location for astronomical observation.

Development of a New Correlation Model for Heat Transfer in Solar Air Heater with Corrugated Absorber Plates Using Swarm Optimization

Solar air heaters play a crucial role in distributing heated air at low to medium temperatures. The heart of these systems lies in the absorber plate, which directly absorbs solar heat energy and then efficiently transfers it to the flowing air. However, the challenge lies in achieving optimal thermal efficiency by modifying the absorber plate roughness. Traditional smooth absorber plates have a limited contact area for heat transfer, leading to suboptimal performance. Using passive techniques, such as corrugation on the absorber plate, may increase thermal efficiency by creating turbulence in the laminar sublayer. In this study, corrugated solar air heaters are considered, with the absorber plates roughened into square, semicircular, and triangular ribs. The flow characteristics of heat due to the roughness of the absorber plate is simulated using the computational fluid dynamic (CFD) technique. The ANSYS Fluent 2019R3 is used to investigate the turbulent air flow in the absorber plate. The simulation analyses are performed over a Reynolds number range of 4000–18,000 using three different pitches. As the main contribution, two different model equations, namely M1 and M2, for the correlation model of the solar heat transfer were proposed to predict the Nusselt number, where M2 is an original model and M1 is newly established with the fine-tuned coefficients. Also, for the first time in the literature, the recent swarm optimization algorithm, namely Honey Formation Optimization with Single Component (HFO-1), is used to optimize the solar air heater and a comparison study with a popular non-swarm optimization, namely the Generalized Reduced Gradient (GRG) optimization, is provided. The Nusselt number was obtained using HFO-1 with a percentage error (MAPE) of 2.15% and 0.86% for the models M1 and M2, respectively. Moreover, the average achievement of HFO-1 on the proposed correlation models is 50% better than that of the GRG optimization, with respect to the RMSE.

Indoor Airborne Microplastics: Human Health Importance and Effects of Air Filtration and Turbulence

Microplastics (MPs) are omnipresent particles that receive special attention because of their persistent nature and their potential impact on human disease and on the environment. Most MPs are generated by the degradation of larger plastic items such as clothing, car tires, and discarded plastic materials. In indoor environments, where human beings spend most of their time, aerial MP levels are higher, and the majority are fibers produced from textiles. Airborne MPs indoors are a greater potential danger to humans than MPs ingested in food and drink. Fragments small enough to remain substantially suspended in the air column, the small airborne microparticles that are measured as PM10 and PM2.5, become available for assimilation by human beings through respiration, potentially producing various health problems. Larger MPs act by ingestion and skin contact. MPs can carry microorganisms and micropollutants adsorbed to their surfaces, facilitating their uptake and survival within the human body. Indoor airborne MPs thus represent emerging pollutants of fast-growing concern that are especially important as potential invaders of the human respiratory system, reaching the alveoli of the lungs and finally entering the circulatory system and other tissues. Since this direct human exposure to MP contamination via indoor air is so important, we discuss in this article the ways in which MP concentration and dispersal in indoor air can be affected by air turbulence that is induced by anthropogenic objects such as air conditioners, filters, and purifiers. Much evidence is equivocal and further research is necessary.

Air-jet impact craters on granular surfaces: a universal scaling

Craters form as the lander's exhaust interacts with the planetary surfaces. Understanding this phenomenon is imperative to ensuring safe landings. We investigate the crater morphology, where a turbulent air jet impinges on granular surfaces. To reveal the fundamental aspect of this phenomenon, systematic experiments are performed with various air-jet velocities, nozzle positions and grain properties. The resultant crater morphology is characterized by an aspect ratio. We find a universal scaling law in which the aspect ratio is scaled by a dimensionless variable consisting of the air velocity at the nozzle, the speed of sound in air, the nozzle diameter, the nozzle-tip distance from the surface, the grain diameter, the density of the grains and the density of air. The obtained scaling reveals the cross-over of the length scales governing the crater aspect ratio, providing a useful guideline for ensuring safe landings. Moreover, we report a novel drop-shaped sub-surface cratering phenomenon.

Design and assessment of an adapted absorber solar air collector tailored for sustainable drying applications

The design of a relevant solar air collector (SAC) is imperative to make the drying industries self-reliant and sustainable in terms of energy. However, the literature doesn’t describe the coherent design assessment of SAC, and its viability for a drying system provided the scale-up opportunity for commercial applications. Hence, the present work was devoted to estimating the heat load for a particular drying condition, a methodological understanding of SAC design, and an investigation of the performance of the newly developed solar collector. The essential design criteria were the moisture content of fresh and intended dried items, physical attributes of items, dryer capacity, preferred drying temperature, projected drying duration, required air speed (based on dryer type), and local climate (solar radiation, ambient temperature and relative humidity). The regular semi-hexagonal shape aluminium (Al) sheet was chosen to introduce air turbulence while maximizing the surface area available for heat transfer. The regular semi-hexagonal absorber was outfitted with helical springs to generate air turbulence and augment heat transfer. A double glazing (polycarbonate) of 5 mm apart was mounted to impede radiation heat loss. Three successive days of the experimental study showed that the average temperature increases of air passing through SAC were 36.02 °C, 37 °C, and 39.2 °C. The optimal tilt angle with the horizontal surface was found to be 35° in a south-facing direction for the month of January. The highest energy efficiency was found to be 40.5 %, while the lowest was found to be 24.73 %. The sustainability index of the SAC was found to be 1.02. The experimental results clearly demonstrate that the designed SAC was capable of supplying adequate heat energy (at the minimum of 155.86 W/hr.) to meet the necessary heat load (125.82 W/hr.) for agro-products drying at the designed capacity.

Turbulent diffusion and air pollution: A comprehensive review of mechanisms, impacts, and modeling approaches

Turbulent diffusion is often a desirable phenomenon in many contexts, but it also presents significant challenges, particularly in the realm of air pollution. Air pollution, a universally recognized and frowned upon issue, degrades air quality and poses serious long-term health risks. Turbulent flows, characterized by chaotic and random fluid motions, give rise to turbulent diffusion, a process that acts as a transport mechanism for dispersing pollutants in the atmosphere. Despite its inherent complexities, the study of turbulent diffusion has advanced significantly, building on foundational concepts like Osborne Reynolds' decomposition in the 1850s and extending to Kolmogorov's length scale framework. These developments have enabled a deeper understanding of turbulent diffusion and its wide-ranging applications across various fields as new methods are continuously employed to broaden the scope of research and application.

A New Drying Method of Thermolabile Flexible Endoscope Channels by Laminar and Turbulent Airflow: A Prospective, Randomized-Controlled, Single-Center, Proof-of-Concept Trial.

International guidelines suggest different possibilities for drying of endoscopes during reprocessing. Clinical results of these available drying methods are not satisfactory. The aim of this study was to compare the drying cycle of a standard endoscope washer-disinfector (EWD) (standard drying method [SD]) with a shortened mandatory drying by the EWD followed by a special drying device using laminar and turbulent air flow (novel drying method [ND]). Sixty endoscopes (duodenoscopes, colonoscocopes, and gastroscopes) from 3 different manufacturers underwent high-level disinfection and drying depending on the randomization group. Operational time of drying was measured for both groups. Residual fluid in the channels was measured using a laboratory scale. After a 14-day storage period, a sample of the endoscope channels was obtained to determine bacterial contamination. ND had significantly fewer residual water in endoscope channels (SD: 90% vs ND: 0%; P < 0.001) after high-level disinfection and drying and less bacterial contamination after storage for 14 days (SD: 47% vs ND: 20%; P = 0.028). Time consumed for drying in ND was also significantly shorter (SD: 16 minutes 4 seconds vs ND: 5 minutes 59 seconds; P < 0.001). Drying with a special automatic drying device was superior compared with an EWD's drying program as evidenced by no measurable residual water, reduced microbiological contamination, and a more than 2-fold decrease in operational time. Thus, drying by laminar and turbulent airflow may represent an attractive alternative to the currently used standard approach in the reprocessing process of flexible endoscopes.

Near-field propagation of a flat-topped gaussian beam: analysis in weakly ‎turbulent atmospheres

We investigate the analysis of optical communication employing the shape beams, definitely concentrating on the effect of factors on the physical characteristics of a Flat Top Gaussian (FTG) beam. The propagation of a beam of laser light in the atmosphere layer is disposed to being affected by many optical phenomena such as scattering, absorption, and turbulence. These phenomena arise from differences in the scintillation index and the intensity modes realized in the source and receiver planes. This work is a numerical investigation of the FTG laser beam as it beams trekking through a zone of low turbulence using open-source software. This simulation will be conducted using a mathematical model derived from the split-step beam propagation technique. The intensity distributions of the source plane and the average intensity is received in air turbulence are computed, with an extra contour at the transducer plane. The Rytov approach to develops the scintillation index, structural constant, source size, and supplementary parameters to measure the weak turbulent model. Furthermore, these factors are studied in the context of near-field propagation. Also, the impression of the scintillation and wander of the beam is assessed. All simulated results are analyses and contrasted with the TEM00 Gaussian beam. At last, these discoveries are compared with the data obtained in the experimental piece of the study, additionally by applied in laser applications.

Microplastic dynamics and risk projections in West African coastal areas: Developing a vulnerability index, adverse ecological pathways, and mitigation framework using remote-sensed oceanographic profiles

Microplastic pollution presents a serious risk to marine ecosystems worldwide, with West Africa being especially susceptible. This study sought to identify the key factors driving microplastic dynamics in the region. Using NASA's Giovanni system, we analyzed environmental data from 2019 to 2024. Results showed uniform offshore air temperatures due to turbulence (25.22–45.62 K) with significant variations nearshore. Salinity levels remained largely stable (4 PSU) but slightly decreased in southern Nigeria. Surface wind speeds rose from 4.206–5.026 m/s in Nigeria to over 5.848 m/s off Mauritania, while eastward stress hotspots were prominent in Nigeria and from Sierra Leone to Senegal. Photosynthetically available radiation (PAR) beam values peaked off Mauritania and dipped from Nigeria to Sierra Leone, with the inverse pattern observed for diffuse PAR. Hotspots of high absorption, particulate backscattering, elevated aerosol optical depth, and remote sensing reflectance all pointed to substantial particulate matter concentrations. The Microplastic Vulnerability Index (MVI) identifies the coastal stretch from Nigeria to Guinea-Bissau as highly vulnerable to microplastic accumulation due to conditions that favor buildup. In contrast, moderate vulnerability was observed from Guinea-Bissau to Senegal and in Mauritania, where conditions were less extreme, such as higher offshore temperatures that could promote widespread microplastic suspension and cooler nearshore temperatures that favor sedimentation. Increased turbulence and temperatures in coastal areas of Senegal and Mauritania may enhance microplastic transport and impact marine life. In Nigeria, stable coastal conditions—characterized by consistent temperatures, low turbulence, and uniform salinity—may lead to increased persistence and accumulation of microplastics in sensitive habitats like mangroves and coral reefs. These findings highlight the need for region-specific management strategies to address microplastic pollution and effectively protect marine ecosystems.

Turbulent impinging air jet for cooling the heated surface

The present work deals with the experimental and numerical study of steadystate conjugate heat transfer during impingement of turbulent air jet over a heated stainless steel. The plate is heated using copper heater located at the middle. The temperature field is measured using an infrared camera and compared with the numerical simulations. Numerical simulations are performed using three-dimensional finite volume based formulation. The turbulence shear-stress transport (SST) is modeled using k−ω model based on the Reynolds averaged Navier Stokes (RANS) equations. The numerical simulations are in good agreement with the experimental data with marginal discrepancy in the steel plate region due to the contact thermal resistance between steel and copper. It is observed that the local Nusselt number increased in the stagnation region with increasing velocity of the impinging turbulent flow and practically unaltered in the region of the steel plate.

Anomalous intensification of vortex heat transfer in the case of separated air flow over an inclined groove in a hot isothermal region of a flat plate

Anomalous heat transfer intensification in turbulent separated air flow over a long groove of moderate depth made in a plate inclined at an angle of 45°to the freestream is revealed both experimentally and numerically. The region under investigation includes a rectangle heated to 100°C by saturated water vapor. The Reynolds number varied from 103to 3×104. Using the gradient heatmetry the twofold increase, as compared with the case of a flat plate, of the heat transfer coefficient on the groove bottom is established at the Reynolds number Re = 3×104. The relative Nusselt number in different regions of the groove is determined both in the physical experiment and in the RANS calculations with the application of multiblock computational technologies and the SST model in the VP2/3 software package. The results are in good agreement in the turbulent flow regime at Re = (5, 10, and 30) ×103.

CFD design and testing of an air flow distribution device for microwave infrared hot-air rolling-bed dryer

In this study, a new microwave infrared hot air rolling bed dryer (MIHRBD) was developed and computational fluid dynamics (CFD) techniques were introduced into the design process of the integrated drying system. The structure of the air distribution device was optimised to improve the airflow uniformity over the curved surface of the rolling bed in the microwave-hot air drying combined equipment. The research findings reveal that, across eleven models, the outlet airflow velocity stabilises once the number of mesh elements reaches 5 million, achieving significant computational accuracy at that point. Optimizing components like the uniform air distribution pipe, turbulence plates, and wind deflectors significantly enhanced airflow distribution uniformity by 52.1%. The best airflow and temperature distribution uniformity on the rolling bed surface was achieved when the inlet airflow velocity ranged from 1 to 3 m s−1, with minimum Vd, Uv and temperature non-uniformity coefficients of 0.007 m s−1, 7.2% and 0.2%, respectively. Validation tests on the MIHRBD pilot equipment showed that after optimizing the uniform air distribution device, the minimum temperature difference on the pleurotus eryngii surface was 3.1 °C. This confirmed the feasibility of the computational fluid dynamics method. Introducing hot air significantly enhanced pleurotus eryngii's drying uniformity, with the Page model effectively predicting the MIHRBD drying process. This study provides technical support for future developments in this field of equipment manufacturing and drying process analysis.

Turbulence effect on disk settling dynamics

Turbulence can have a strong effect on the fall speed of snowflakes and ice crystals. In this experimental study, the behaviour of thin disks falling in homogeneous turbulence is investigated, in a range of parameters relevant to plate crystals. Disks ranging in diameter from 0.3 to 3 mm, and in Reynolds number $Re = 10\unicode{x2013}435$ , are dispersed in two air turbulence levels, with velocity fluctuations comparable to the terminal velocity. For each case, thousands of trajectories are captured and reconstructed by high-speed laser imaging, allowing for statistical analysis of the translational and rotational dynamics. Air turbulence reduces the disk terminal velocities by up to 35 %, with the largest diameters influenced most significantly, which is primarily attributed to drag nonlinearity. This is evidenced by large lateral excursions of the trajectories, which correlate with cross-flow-induced drag enhancement as reported previously for falling spheres and rising bubbles. As the turbulence intensity is increased, flat-falling behaviour is progressively eliminated and tumbling becomes prevalent. The rotation rates of the tumbling disks, however, remain similar to those displayed in still air. This is due to their large moment of inertia compared to the surrounding fluid, in stark contrast with studies conducted in water. In fact, the observed reduction of settling velocity is opposite to previous findings on disks falling in turbulent water. This emphasizes the importance of the solid-to-fluid density ratio in analogous experiments that aim to mimic the behaviour of frozen hydrometeors.

СОВРЕМЕННОЕ СОСТОЯНИЕ ИССЛЕДОВАНИЙ И ПРОГНОЗИРОВАНИЯ ВЛИЯЮЩЕЙ НА АВИАЦИЮ ТУРБУЛЕНТНОСТИ В СВОБОДНОЙ АТМОСФЕРЕ

Three main physical processes are responsible for generation of turbulence affecting the aircraft: (1) hydrodynamic instability of the airflow stratified in wind and temperature (Kelvin-Helmholtz instability), which manifests itself in origination of turbulent patches called clear-air turbulence (CAT) in the free atmosphere; (2) breaking of large-amplitude mountain waves over the obstacles and at their leeward slopes, which causes so called orographic turbulence or mountain wave turbulence (MWT); (3) outflow of highly turbulent air from convective storms, which leads to the formation in their vicinity of turbulent zones of deep convection, that is, convectively induced turbulence (CIT). In the paper, the state of the art in studying and forecasting the turbulence generated by the mentioned physical processes is considered. The present short-range forecasting and nowcasting techniques are characterized by transition to the universal standard for intensity of aviation turbulence, that is, to the energy dissipation rate (EDR) defined in terms of the theory of homogeneous and isotropic turbulence, and by taking into account the informativity of empirical turbulence diagnostics. For the CIT nowcasting, special techniques for convection diagnosis are developed based on the satellites, radars, and lightning registers data.

Free Space Optical Communication and its Implementation Using Diffractive Optical Elements Using Artificial Intelligence (AI)

Background: Free Space Optics (FSO) is a wireless data transmission method for infrastructure that uses laser beam energy to transmit information waves through the atmosphere. Furthermore, due to its high bandwidth potential and simple deployment, FSO has garnered considerable interest. However, atmospheric turbulence and misalignment present obstacles to establishing dependable and effective FSO links. Objective: For systems varying from space invariant to totally space variant, the optimal design of free-space optical connectivity systems using diffractive optics is found from an engineering perspective. Parameters such as the light's wavelength, the system's total number of optical sources and detectors, their sizes, and their spacing are used to determine the system's volume. Another important parameter is the diffractive lens's f-number. Diffraction Optical Elements (DOEs) have emerged as a promising means of addressing these difficulties. Also, the patent related to automated honey beehive box gives the insight of its monitoring system. Methods:: This paper provides an overview of the implementation and advancements of FSO systems utilizing DOEs, including the fundamental principles, design considerations, and performance improvements. The study discusses the basics of diffraction and the role of DOEs in FSO systems. It explores the diffraction grating equation and the Huygens-Fresnel principle to understand wave propagation and interference phenomena. Design considerations for FSO systems equipped with DOEs are discussed, including the selection of appropriate DOEs and evaluation of performance benefits. The study also investigates the application of AI methods, such as machine learning and deep learning, in optimizing FSO systems with DOEs. Results: A thorough overview of Free Space Optics (FSO) systems utilizing Diffraction Optical Elements (DOEs) is given in this review study. It examines diffraction theory and DOE use in FSO, emphasizing their potential for beam forming, beam steering, and adaptive optics. The study examines FSO with DOE design concerns, performance improvements, applications, and future approaches. FSO systems may overcome problems with air turbulence, misalignment, and fading by using the characteristics of DOEs, opening the door for dependable and effective wireless communication. Conclusion: In conclusion, the effect of DOEs on BER efficiency is also modified by the obscuration ratio. Transmission power is increased when more DOEs are used by an amount defined by their obscuration ratios. Additionally, because of the increased power complement in these systems, the effect of DOEs is more pronounced. The integration of AI further enhances FSO capabilities by providing adaptive optimization, fault detection, predictive maintenance, and improved security. Future research directions may include exploring advanced AI techniques and conducting practical implementations of FSO systems with DOEs for various applications, particularly in Internet of Things (IoT) scenarios.

Efficient aerodynamic design using BézierGAN and model order reduction: A computational study

Bézier Generative Adversarial Networks (BézierGANs) is one of the most widely used Convolutional Neural Network (CNN) technique-based algorithms for generating smooth curves to analyze and optimize complex shapes and flow patterns, particularly aerodynamics. Airfoils, the basic cross-sectional shape to design air wings, are generated here by selecting the vital parameters wisely after alternating the typical BézierGANs algorithm instead of relying on pre-existing models. When these predicted airfoils are used to develop the physical structure of the adjacent air layer to observe the phenomena, they become the subject of computationally expensive simulations of turbulent airflow. Simulations of turbulent airflow that are computationally expensive are required when these anticipated airfoils are utilized to create the physical structure of the adjacent air layer to monitor the physical events. To prevail over this computational burden, the Model Order Reduction (MOR) technique is applied to develop the best-fitted lower-order model of the original turbulent air layer model around the airfoils by filtering the most effective system's singular values while preserving all the essential characteristics of the original large-scale model. As evidence of the effectiveness of the Reduced Order Model (ROM) of the turbulent air layer regarding the truncation of the design time and computational costs, the comparative analysis of the computational time is occupied by the original and prescribed system to ensure about 99.7660% of less time consumption by the ROM. The regeneration of the reduced-order physical model is also covered in this paper, which analyzes the physical behaviors regarding the air pressure and the velocity patterns of the airflow around the airfoils and compares the similarities to the physical characteristics of the Full Order Model (FOM). It was found that the ROM can be one of the best alternatives to FOM in real-life implementation.

Planar Concentration Field Measurement In A Transient Jet Using Mie Scattering

An experimental method for time resolved concentration measurements in the near field of a transient starting turbulent air jet is presented. Planar Laser Mie Scattering (PLMS) using DEHS droplets produced by a Laskin nozzle as tracers of concentration is applied on an air jet with Reynolds number of 62.000 and is recorded with 10.000 frames per second. A jet penetration of about 20 nozzle diameters into the ambient environment is resolved with more than 100 frames. A linear response between grey scale values and concentration is found for mixtures up to 13% of the air-particle flow from the Laskin nozzle mixed with clean air. The calibration is based on images with no particles and images with a homogeneous particle concentration. A correction for light scattered by particles outside the laser sheet is proposed. The experimental results agree well with mean concentration measured with other techniques.