Inlet Air Research Articles

Effects of Tip Injection on a Turbofan Engine with Non-Invasive High-Speed Actuators

This paper presents an analysis of the stability margin improvement (SMI), which is also known as stall margin improvement, achieved by continuous tip air injection. New piezoelectric actuators were designed and manufactured with a new engine inlet for the Larzac 04 C5 jet engine. It has noninvasive injection positions that do not have any measurable effect on the inlet air flow when it is switched off. The main focus of the system design was to achieve high power of the injected air and, as a result, a high SMI. The results presented enable a maximum SMI of 99%. A variety of engine operating conditions and injection positions were experimentally tested and discussed regarding SMI. Additionally, the complex relationship between SMI gains and thrust specific fuel consumption (TSFC) is explored in a power balance analysis, revealing a trade-off between SMI improvement and increased energy consumption.

Numerical investigation on positional optimisation of extra air channels for conventional battery cooling models

Abstract Currently, as the use of electric vehicles is rapidly increasing, the battery pack that powers the system is one of the most important issues. Li-ion batteries are the most preferred battery type because of their high energy density, fast-charging capabilities, and long life. However, the heat generated by the current drawn by the system affects battery performance and poses safety risks. Effective battery thermal management systems (BTMSs) are required to quickly remove this heat from battery packs. For this purpose, three different models were created by adding extra air inlet channels to three points on the 4 × 6 battery module, and their cooling efficiency was investigated. Numerical analyses of the models were performed using the Ansys Fluent software package, and comparisons were made both among themselves and with the conventional model. The models (Basic Model, Model A, Model B and Model C) were analyzed at four different Reynolds numbers (104, 2 × 104, 3 × 104, and 4 × 104) calculated according to the air velocity and channel cross sections. Based on these results, the calculated Nusselt number (Nu), temperature values, friction factor, pressure drop, and PEC (performance criteria) values were obtained. Compared to the Base Model, the most effective methods were determined as Model A, Model B and Model C, respectively. Adding extra cooling channels to the battery module resulted in at least a 23.86% increase in Nu numbers, 40% lower pressure drop, and a 3.5% PEC number.

Investigating the Influence of Axial Velocity and Tangential Velocity on Combustion Characteristics in a Cylindrical Vortex Combustor

Efficient combustion is essential for various applications, including gas turbines, industrial furnaces, and propulsion systems. The interaction between axial and tangential velocities significantly influences combustion stability, flame shape, and pollutant formation. However, a comprehensive understanding of these effects in a cylindrical vortex combustor remains elusive. The primary of this study is to analyse how axial and tangential velocities impact combustion characteristics within the Cylindrical Vortex Combustor (CVC). Specifically, we aim to determine the optimal velocity combination that ensures stable combustion, minimal emissions, and efficient energy release. The CVC geometry was modelled, and the simulations were conducted for various axial and tangential velocity combinations by Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent software were employed to explore the behaviour of the vortex combustor under varying conditions. The Navier-Stokes equations, energy equation, and species transport equations were solved. Air inlet conditions included a mass flow rate of 40 mg/s and for fuel inlet was set 3.0 to 4.0 mg/s through an equivalence ratio (j) ranging from 0.5 to 1.5. The numerical findings indicate higher axial velocities enhance mixing and promote stable combustion and this velocity component excessive lead to flame blowout. The tangential velocities influence vortex strength and flame stability and will enhances recirculation and flame anchoring. Due to these conditions, an optimal balance between axial and tangential velocities yields efficient combustion. Understanding the interplay between axial and tangential velocities is essential for designing efficient vortex combustors. The findings provide valuable insights for optimizing combustion systems, reducing emissions, and improving overall performance.

Analysis and optimization of thermal management system for super elliptic battery cell geometry in electric vehicles

Battery technology is the most important parameter affecting the range of electric vehicles. One of the biggest concerns in battery systems developed for electric vehicles is in particular, the temperature in the cells of lithium-ion (li-ion) batteries allows a limited degree of variation (°C) within the entire battery pack. Therefore, today’s electric vehicle research and development studies are focused on this issue. In this study, the battery systems of electric vehicles are parametrically designed with a 3D solid modeling program according to the super ellipse geometry, which offers a wide range of geometries, and the thermal management of the battery systems is realized. TM studies were done in ANSYS CFX. Air was selected as the coolant and the effect of different parameters (cell geometry, inter-cell distance, cell height, heat flux, inlet air velocity, and inlet air temperature) on the battery cell temperature was analyzed. D-Optimal experiment design was created with MATLAB. A two-alternative optimization study was carried out as constrained function local optimization and genetic algorithm optimization. Accordingly, it was observed that the battery pack gives the best thermal result when the distance between the cells increases and the inlet air temperature decreases. In addition, when the most well-known envelope type, cylindrical and rectangular prism shaped battery geometries in the literature are evaluated, it is concluded that the most ideal result is closer to the envelope type geometry.

Recurrent Neuronal Networks for the Prediction of the Temperature of a Synchronous Machine During Its Operation

This work presents the development of an adaptive thermal protection system for synchronous machines (SMs), taking into consideration the final cooling temperature and the operation point of the machine. This system aims to improve current thermal protections, which consist of a fixed alarm and trip thresholds regardless of the generator’s operating point or ambient temperature. A recurrent neural network (RNN)-based approach has been employed to predict SM temperatures during operation. Multiple tests have been conducted on a specially designed test bench. Inside the windings and iron core of the 5.5 kVA generator, multiple Pt100 sensors have been installed to train the neural network with real temperature values, enabling accurate predictions. The selected RNN model is Long Short-Term Memory (LSTM). Its inputs include electrical variables and the inlet and outlet air temperatures of the SM’s cooling system. The results show that the model accurately defines warning and trip thresholds, significantly improving thermal protection, as these thresholds are no longer fixed values. Additionally, the study suggests validating the model under cooling system failures and exploring its application in water-cooled systems. This research is supported by a patent on real-time thermal diagnostics for synchronous machines, highlighting its potential contribution to predictive maintenance and the monitoring of power generation systems.

Evaporative Condensation Air-Conditioning Unit with Microchannel Heat Exchanger: An Experimental Study

A new evaporative condensation refrigerant pump heat pipe air-conditioning unit based on a microchannel heat pipe heat exchanger is proposed. Performance experiments were conducted on the unit, and the experimental results show that the cooling capacity of the unit in the dry, wet, and mixed modes can reach 112.1, 105.8, and 115.4 kW, respectively, the optimal airflow ratio of the secondary/primary airflow is 2.2, 1.8, and 1.8, respectively, and the EER decreases with increasing airflow ratio. With increasing dry- and wet-bulb temperatures of the secondary-side inlet air, the cooling capacity and energy efficiency ratio of the unit decrease, and the energy efficiency ratio in the wet mode is higher than that in the dry mode, which can prolong the operating hours of the wet mode within the operating temperature range of the dry mode and improve the energy efficiency of the unit. A new calculation method for the refrigerant charge is proposed, and the optimal refrigerant charge is 32 kg based on the experimental results, which agrees with the theoretical calculation results.

Enhancing operational efficiency and compliance through ventilation system designs in radiopharmaceutical facilities

ABSTRACT Maintaining optimal environmental conditions in radiopharmaceutical facilities is essential for operational efficiency, product quality, and regulatory compliance. This study focuses on assessing ventilation systems within the test chamber as a case study to address these critical needs. Using COMSOL Multiphysics, a detailed simulation framework was developed to model airflow and heat transfer dynamics in the chamber. The simulation results were compared with experimental measurements, including inlet velocity, temperature, and heat flux, producing air temperature and velocity profiles consistent with analytical global models. The study compared mixing and displacement ventilation strategies within the test chamber, finding that displacement ventilation was more efficient, providing better control over thermal conditions while minimising temperature variations. In contrast, mixing ventilation, although effective, demonstrated less uniformity in temperature distribution. Additionally, the impact of warm air inlet jets on airflow patterns and temperature distribution was investigated, utilising the Nonisothermal Turbulent Flow, k-ω model interface. Employing the k-ω turbulent model allowed for a comprehensive analysis of complex fluid dynamics, offering valuable insights into airflow patterns and their implications for operational efficiency and compliance. The findings provide facility managers and engineers with a robust methodology for assessing ventilation systems in radiopharmaceutical settings, guiding the design and optimisation of strategies that enhance operational efficiency, ensure regulatory compliance, and protect the integrity of radiopharmaceutical products.

Spatial analysis of airborne bacterial concentrations and microbial communities in a large-scale commercial layer facility.

Spatial analysis of airborne bacterial concentrations and microbial communities in a large-scale commercial layer facility.

Numerical Simulation on the Effect of Different Airflow Schemes in a Large Space

Abstract The underground plant of a pumped storage power station was taken as the object for studying the airflow in a large space. Computational Fluid Dynamics (CFD) is utilized to analyze the characteristics and patterns of airflow organization under summer operating conditions. Three airflow organization schemes including variable inlet dimension, number and air supply velocity are set. The airflow effects are compared according to the air velocity and air temperature distribution. The longitudinal profile of the air supply as well as the horizontal height of the work area are selected. Results demonstrate that a reasonably designed air outlet layout can fulfill the wind speed and temperature requirements for the working area. Moreover, homogeneity and stability of the airflow field in the working zone can be realized.

Antimicrobial and insecticidal activity of spray dried juniper berry (Juniperus communis L.) essential oil microcapsules prepared by using gum arabic and maltodextrin.

Antimicrobial and insecticidal activity of spray dried juniper berry (Juniperus communis L.) essential oil microcapsules prepared by using gum arabic and maltodextrin.

CFD Analysis of Hydrogen Gas Behaviour in a Multi-Zone Flow System: A Parametric Study

The ANSYS CFD analysis made use of hydrogen in this study. The investigation aims at understanding the behaviour of hydrogen gas in such interactions with the inlet air and other fluid zones around it. Such research took advantage of sophisticated simulation tools to offer useful insights into gas flow and mixing patterns, thereby justifying why hydrogen could possibly become an alternative fuel one day (hydrogen is future-oriented). In addition, a model was created to establish the interaction between combustion involving hydrogen as well as tanks of inlet air. This was done on volumes for such tanks. Many factors affect performance and efficiency for different operational conditions of hydrogen gas that were explored through elaborate simulations. These findings should improve our comprehension about physics involved which plays an important role in enhancement of systems using hydrogen for power generation and also help various industries' operations using this element in their processes. It is research that looks at the complicated flow structures and behaviours that arise in fluid domains to uncover key parameters for better designs and more efficient hydrogen systems. Consequently, it is expected that the present study will help future designs of hydrogen technology so that they play a part of sustainable energy source.

NUMERICAL SIMULATION OF AIR COOLING PROCESSES IN A POULTRY HOUSE WITH A TUNNEL-SIDE VENTILATION SYSTEM

During the warm season, when ambient temperatures exceed +28 °C, the tunnel ventilation system is predominantly used in poultry facilities. This system effectively removes excess heat from the environment. However, under conditions of high ambient temperatures and high humidity, specialized systems are required to cool the incoming air and create a controlled microclimate within the poultry house. In ventilation systems, various types of cooling methods are employed to reduce the temperature of incoming air during the summer. Most commonly, these involve water spray systems. The core objective of this study is to conduct theoretical research on regulating heat and mass transfer processes in poultry houses, considering both internal dynamics and interactions through external barriers. This study proposes an innovative approach to cooling incoming air in poultry house ventilation systems. The method utilizes water sourced from underground wells and heat exchangers-recovery units (recuperators) to efficiently cool the incoming air. As a result of the numerical modeling, the temperature distribution within the service zone of the poultry house was determined. When heat exchangers are used, the inlet air temperature in the facility is maintained at +20 °C. The temperature increase along the length of the facility is clearly observed in the provided diagrams. The outlet temperature of the cooled air is +27.89 °C, which is attributed to heat generated by the poultry and the warming of the poultry house walls by external air. Thus, the air temperature within this cooling system does not exceed permissible limits. Analyzing the numerical modeling results at a height of 0.7 m from the floor level, it was concluded that no more than 2% of the poultry would experience discomfort under the proposed cooling system. The average air velocity is 0.83 m∙s⁻¹, and the air temperature is +23.64 °C.

Effect of wedge strut angle on shock wave generation and supersonic air-fuel interaction

This research work mainly focusing on the result of shock wave strike on shear mixing layer for different angles of wedge strut fuel injector. This study examines the shock waves produced by a wedge-shaped strut, utilizing different divergence angles to alter the shock angle. The initial compression wave is created at the leading edge of wedge strut, while a second wave originates at the strut’s end. These shock waves interact and converge at a specific point within the shear mixing layer, enhancing hydrogen-air mixing. The study begins with a standard DLR (German Aerospace Centre) scramjet combustor model equipped with a strut featuring a 12-degree divergence angle. This angle is then varied to 4, 8, and 16° to analyse trends in oblique compression wave formation and their result on the shear dispersion layer. Numerical simulations are executed using ANSYS Fluent and the Reynolds-Averaged Navier-Stokes (RANS) equations to demonstrate the influence of altering strut angle on shock wave formation. For an 8-degree strut, the shock waves converge at a point 136 mm downstream from the air inlet, substantially intensifying air-fuel mixing and improving combustion efficiency. The reaction rate increases by 12% with the 8-degree strut compared to the original 12-degree design. This improvement leads to a 7% higher combustion efficiency relative to the standard DLR scramjet combustor.

Parameter optimization of a passive dust removal system at the coal transfer point of a crushing station

The dust pollution is severe during the coal transfer process in the coal transfer system. To reduce dust generation, a simulation model was established based on the crushing station of the Heidaigou open-pit coal mine. The EDEM-Fluent coupling method was used to calculate the induced airflow generated by the coal flow, and a passive dust removal system, incorporating a return air duct, baffle plate, and dust barrier, was designed and optimized to balance the static pressure difference between the upper and lower parts of the system and suppress dust overflow. The study results indicate that the optimal dust suppression effects are achieved with a return air duct height (h) of 1.6 m, a distance (L 1) of 2.0 m between the air inlet and the discharge pipe, a distance (L 2) of 0.5 m between the baffle plate and the return air duct, a distance (L 3) of 0 m between the dust barrier and the air inlet of the return air duct, and an angle (θ) of 20° toward the transfer chute. Based on these optimized parameters, the passive dust removal system was applied to the coal transfer system at the crushing station, resulting in an average dust concentration reduction of 71.76%.

Utilizing an experimental design and scale up of a wet fluidized bed agglomeration process, to produce novel carbon agglomerates and tablets

Wet granulation and agglomeration processes are widely used in the pharmaceutical industry. This study was performed, aimed at developing a systematic approach to scale up a carbon agglomeration process from 10 kg to 100 kg. The goal was to achieve similar granule sizes with different granulators during production. The formulation of the powder bed at the start of the agglomeration process was based on carboxymethyl cellulose as a binder, carbon and peroxide powder. In the first production step this composition was used to produce agglomerates. Agglomerates were evaluated for particle flow and particle size. Finally, compressive strength of cylindrical carbon tablets was measured, following compression with a five cavity mechanical press. It was found that the agglomeration liquid quantity, the inlet air flowrate and the droplet size distribution play a fundamental role in the upscaling process. Therefore, these mentioned parameters had to be systematically scaled up for different batch sizes in order to achieve similar particle growth in the different fluidized bed sizes. A previous study, through a design of experiments has shown that a target geometric mean granule size of around 575 µm is desirable in terms of the granules flowability and granules properties. For example: The compressive strength of the carbon tablets. Furthermore, a DoE for the spraying parameters was applied to compare the final tablet properties. The scale up process from a laboratory to a production size granulator, was successfully performed. This was based on the granule’s properties and the mechanical stability of the carbon tablets.

Modelling Analysis of Face Shield Effectiveness against COVID-19 Transmission

The ongoing COVID-19 pandemic necessitates effective protective measures to mitigate virus transmission. This study employed Computational Fluid Dynamics (CFD) to evaluate the efficacy of two face shield models in blocking COVID-19 transmission under three conditions: normal speech, coughing, and sneezing. One model replicates a common commercial product, and the other introduces an innovative design. A simplified human model with dimensions of 760 × 300 mm and a mouth air inlet area of 360 mm² was used for the simulation. Two types of face shields were modelled: one with a simple curved structure (Model 1) and another with a rectangular structure providing a side cover (Model 2). The computational domain was defined with dimensions of 3.5 m x 2.8 m x 2.3 m, and simulations were conducted using the finite volume method with ANSYS Meshing and Fluent for solver preference. The governing equations for the incompressible flow were applied. The simulations revealed that both face shields effectively blocked the direct airflow to the face across all conditions (speech, coughing, and sneezing). However, the structure of the face shields significantly alters the airflow patterns. Model 2, with its rectangular structure, provided better coverage and directed the airflow away from critical areas. Despite their effectiveness in blocking direct contact with airborne particles, face shields alone do not provide sufficient protection against virus transmission, especially for finer aerosol particles. Face shields can obstruct direct airflow but are inadequate as standalone protective measures against COVID-19 transmission. Therefore, the combined use of face shields and face masks is recommended for enhanced safety.

Development and Analysis of a Modified H-Type Air-Cooled Battery Thermal Management System

Abstract Thermal management of lithium-ion batteries is an important design consideration for electric vehicles (EVs) as it affects the performance and life of the batteries. Given the thermal vulnerability of lithium-ion batteries when subjected to high charging and discharging rates, effective cooling designs for battery packs are necessary. The current work proposes a cooling design with better heat dissipation and maximum temperature difference (ΔTmax). The design improves the reference H-type battery thermal management system (BTMS). In this system, an open triangular pitch is formed at the top of the cell enclosure, and the bottom part of the cell enclosure is tapered from both sides and toward the center. The effect of taper height, pitch height, pitch opening dimensions, cooling channel spacing, inlet air velocity, ambient temperature, and discharge rate on the system's performance was investigated using computational fluid dynamics (CFD) simulation. The experiment was conducted based on the proposed design, and the results were used to verify the numerical model. The results are discussed using the flow streamlines, velocity contours, temperature contours, cooling channel velocity plots, and temperature plots. The results show that the maximum Tavg and the ΔTmax of the battery pack were reduced by 1.34 °C (3.6%) and 1.58 °C (93.5%), respectively, compared to the reference H type.

Microencapsulation of flavored liquor by spray drying: Optimization using response surface methodology and genetic algorithm-based support vector regression

Flavored liquor microcapsules were prepared by spray drying with baijiu as the main core material, and gelatin, β-cyclodextrin, and maltodextrin as the composite wall material. The experiments were first conducted in a lab-scale spray dryer with ethanol retention as the objective function, and feed solid content, inlet air temperature, and feed rate as the influencing factors. The operating parameters were optimized using the commonly used response surface methodology (RSM) and a machine learning method of genetic algorithm-based support vector regression (GA-SVR). Subsequently, the pilot experiments were conducted in a pilot-scale spray dryer based on the optimized parameters. The qualities of products from the two dryers were evaluated. The results indicated that the ethanol retentions for the lab-scale and pilot-scale dryers were 47.78% and 46.07%, respectively. Compared with the RSM, the GA-SVR opted for a strategy of simultaneously increasing both inlet air temperature and feed rate while maintaining almost the same ethanol retention. The optimal operating parameters were determined as 35.7 wt% of feed solid content, 110 °C of inlet air temperature, and 9.5 mL·min−1 of feed rate for the lab-scale dryer and 28 mL·min−1 for the pilot-scale dryer. The microcapsules prepared by the two dryers exhibited a spherical shape with fine texture, and had a certain degree of heat resistance. The pilot-scale dried products showed slightly better flowability and lower residual water content. This work is aimed to provide a practical guidance for the machine learning method in optimizing the spray-dried microencapsulation.

Techno-Economic Analysis for the Costs of Drying Chickpeas: An Example Showing the Trade-Off Between Capital and Operating Costs for Different Inlet Air Temperatures

This study investigates the implementation of new drying schedules for chickpeas, a significant pulse, incorporating a techno-economic analysis. The research also explores the reduction in anti-nutritional factors, such as trypsin inhibitors, through fluidized-bed drying with an air recycling system. The processing cost per unit mass of chickpeas is predicted to decrease with an increasing recycling ratio, from over AUD 1.32/kg of chickpeas with no recycling down to AUD 0.0885/kg of chickpeas at a ratio of 99%. With no air recycling, the lowest inlet air temperature (40 °C) gives the lowest cost, but near the optimum recycling ratio, the highest inlet air temperature (80 °C) is best. This pattern is followed when considering equivalent carbon dioxide emissions, with the lowest emissions (over 0.259 kg CO2 (kg chickpeas)−1) corresponding to high recycling ratios and high inlet air temperatures. The use of air recycling should cause no significant challenges when implementing a drying schedule for trypsin inhibitor reduction in chickpeas.

Extended Second Law Analysis for Turboramjet Engines

Turbine based combined cycles (TBCC) monopolizes the benefits from the two different thermodynamic cycle configurations involved. The TBCC, which is based on an irreversible Brayton cycle, considered in this study is a wraparound configuration turboramjet engine. The turboramjet can be utilized in either turbojet (afterburner (AB) being ON or OFF), ramjet and even dual mode operation. However, for the dual mode operation the turbojet engine AB are considered to be ON. In addition, the ramjet thermodynamic assessment considers multi-oblique shock and single normal shock solution and Rayleigh flow calculation for the combustion chamber. The performance analysis and comparison for the turboramjet engine for dual mode operation is based on a maximum power approach under variations of Mach number and altitude. Moreover, the dual mode operation considered variations of inlet air mass flow; the split of air mass flow between the turbojet and ramjet. In addition, a brief comparison is provided of the turbojet while the afterburner is in ON or OFF mode utilizing the maximum power, EPLOS and PLOS optimization functions for variations of altitude and Mach number. Moreover, a component based evaluation under maximum power conditions for variation of Mach number is provided. The turbojet with an AB shows greater advantage at Mach number higher than unity as well as attaining maximum power outputs at minimum PLOS for lower compressor ratio parameters (θ_c). Whereas the turboramjet indicates that as the split of inlet air mass flow to the ramjet is increased beyond 50% the advantage in terms of η_th, η_o, f, TSFC, I_a, thrust and ν_NOZZLE far supersede that of the turbojet with an AB.