Fan Rotational Speed Research Articles

Measuring and Modeling Mechanical Ventilation for Long-Term Environmental Monitoring in Large Commercial Laying Hen House.

Determining ventilation rates in commercial animal buildings has been technically challenging. This study aimed to develop an innovative method and a ventilation model and provide new insights into animal building ventilation. A layer house with 46 fans was studied over six months. A full-size and fast-response portable fan tester was developed for on-site fan ventilation measurement. Results indicated that the house differential pressures (dP) varied from +10.4 to <-100.0 Pa but remained between -10 and -30 Pa for 75.7% of the time. The mean house dP was -18.1 ± 8.9 Pa (mean ± standard deviation). Fan rotational speeds ranged from 495 to 580 rpm, with an average of 555 ± 14 rpm. Daily mean house ventilation rates ranged from 1800 to 22,142 m3 min-1, averaging 4.68 m3 h-1 per hen. This study concluded that house dP can be greatly affected by strong winds in addition to fan operations and air inlet openings. Fan rotational speeds are influenced by pulley sizes and fan belt maintenance. On-site fan tests with the fan tester can generate reliable data for fan ventilation characterization. Fan models that incorporate both fan rotational speeds and differential pressures considerably improve ventilation rate calculations.

Damage to a High Bypass Ratio Fan During Uas Ingestions

Abstract Foreign object ingestion into engines has been studied for many years, but the focus has been on soft bodies (i.e., birds, ice). Recently, there has been a dramatic increase of uncrewed aircraft systems (UAS) in the airspace that represent a new threat to aircraft engines due to key components like the motor, battery, and camera being composed of hard components. Due to the differences between hard bodies and soft bodies, studies are required to understand the new threat these UAS pose to aircraft. The objective of this study is to investigate the impact of various factors such as impact orientation, fan rotational speed, relative translational speed, and radial impact location on the damage caused to a representative fan assembly. This study aims to analyze the sensitivity of these factors and their influence on the overall damage to the fan. The ingestion simulations will use a representative fan assembly model and a UAS model that has been experimentally validated at the conditions of an ingestion. This work will identify critical parameters of the ingestion and then utilize them to anticipate the extent of damage that may arise during specific stages of a flight where an ingestion is most probable. Moreover, it also compares these cases with some known baseline cases, such as a fan blade out and bird ingestion of similar mass, to understand the likely severity compared to more studied common cases.

Numerical investigation of the effect of enforced air flow in a closed cavity on temperature distribution of ammonium dihydrogen phosphate crystal with a large aperture

The temperature distribution of a novel Final optics assembly (FOA) made of a square ammonium dihydrogen phosphate (ADP) crystal with a large aperture is examined numerically in this noncritical phase-matching simulation (NCPM). The temperature of the cavity wall is maintained by temperature-controlled, continuously flowing (0.1 m/s) water (313.5 k). The thermal study was first performed numerically inside the cavity with different configurations using the finite volume technique. One fan was placed on one side of the ADP crystal to evaluate the temperature distribution within the cavity and between the crystals. The fan speed is then varied from 10 to 40 rad/s with a step interval of 10 rad/s to evaluate the effect of forced convection. Furthermore, the investigation showed that 20 rad/s is more effective than the other cases. To measure the impact of temperature distribution caused by fan orientation, the fan orientation was adjusted to three different tilt angles (10, 20, and 30 degrees) while the fan rotational speed was maintained at 20 rad/s. The two fans on the side and the two fans on either side of the ADP crystal were also investigated, with different orientations (0, 10, and 20 degrees) and speeds (0, 10, 20, 30, and 40 rad/s). According to the fan speed, direction, number of speeds, and fan locations, the high-temperature spot of ADP crystals can be symmetric, asymmetric, diagonally dominant, center dominant, bottom dominant, or top dominant.

Evaluation of the effects of various fan parameters on the cooking process in commercial cooking ovens

Commercial kitchen ovens are utilized in various capacities and models within commercial enterprises, operating on either electric or gas power. Numerous parameters affect the cooking process. Particularly, for effective cooking in an oven, it’s crucial to evenly distribute airflow over the food. Correct airflow significantly impacts the cooking process. Considering the differences in processing requirements based on the characteristics and quantity of the food (such as temperature, humidity, fan speed, duration, etc.), the method of heat transfer should be primarily assessed. Non-uniform distribution of hot air during the cooking process leads to varied cooking qualities among trays within the oven. Therefore, in achieving effective cooking, factors like oven cavity, number of trays, fan geometry, fan rotation speed, direction, movement intervals, and the turbulent airflow generated by the fan in the cooking chamber need thorough examination. This study analyzed simulation data evaluating the effects of different fan geometries, fan rotation directions, and timing on heat transfer in a prototype electric commercial cooking oven using gastronomic GN-1/1 sized with 10 trays. Additionally, comparison of test and design validation data in the specially developed prototype cooking oven was conducted. Assessments were made with different fan movements (fan diameters, rotation direction, speed etc.) and a fan protection plate in front of the oven to achieve more efficient heat distribution on the food. Depending on various fan parameters, this study contributed to reducing energy consumption in the prototype commercial cooking oven.

Aeroacoustics of a ducted fan ingesting an adverse pressure gradient boundary layer

The aeroacoustics of a boundary layer ingesting (BLI) ducted fan is investigated experimentally. The study examines a ducted fan immersed in an adverse streamwise pressure gradient turbulent boundary layer developed over a curved wall. Aeroacoustics measurements indicate that the noise from the BLI ducted fan results from a complex interaction among the fan, duct and the incoming boundary layer. The fundamental mechanisms of noise generation are explained using a general source separation strategy. A detailed noise comparison is made at varying fan rotational speeds and across a wide range of axial inflow velocities. In a low thrust regime, the noise is found to be driven by the fan loading, coupled with duct acoustics and the haystacking phenomenon. In a high thrust regime, the contribution from duct acoustics diminishes, and the noise is predominantly driven by the fan loading coupled with the haystacking phenomenon.

Research on Aerodynamic Test Validation and the Vector Force Control Method for an E-STOL Fan Wing Unmanned Aerial Vehicle

The concept of the Fan Wing, a novel aircraft vector-force-integrated device that combines a power unit with a fixed wing to generate distributed lift and thrust by creating a low-pressure vortex on the wing’s surface, was studied. To investigate the unique propulsion mechanism of the Fan Wing, a Fan Wing test platform was developed, and experiments were conducted in a wind tunnel. At the same time, numerical simulations were established. In order to further improve the aerodynamic efficiency of the Fan Wing and decouple the control of lift and thrust, an improved scheme for the leading-edge structure of the Fan Wing was proposed, and a numerical analysis was conducted. A Fan Wing unmanned aerial vehicle (UAV) was designed and manufactured using the Fan Wing as the source of lift and thrust for the aircraft, and flight verification was conducted. The wind tunnel tests have proven that the main factors influencing the lift and thrust of the Fan Wing are rotation speed of cross flow fan, angle of attack, and incoming flow. The numerical analysis results of slotting on the leading edge show that the lift and thrust of the Fan Wing can be improved, but also the strength and position of the low-pressure vortices can be controlled. The results of flight tests show that the distributed lift and thrust of the Fan Wing can be directly applied to aircraft without the need for additional propulsion devices. In summary, the aerodynamic characteristics of the Fan Wing can be applied to electric short takeoff and landing (E-STOL) scenarios in urban air traffic.

CFD analysis and optimization of axial flow fans

The axial fan plays a vital role in the safe production of the mine, and in this paper, a mine axial flow ventilator is designed through numerical simulation to meet the demand of air exchange inside and outside of the mine, so as to maintain the oxygen supply of the mine and discharge the harmful gases. Finite element analysis of four structural factors of axial fan blade installation angle, number of blades, deflector plate, rotational speed, drawing fan wind pressure and rotational speed cloud diagram, calculation of axial power, by analyzing the distribution of the cloud diagram to design the shape of the fan blade, and derive the change rule of the wind pressure when changing the structure of the fan. By using gradient descent method to control the percentage of imported mass flow rate, the P-Q performance curve of the fan is obtained, which optimizes its aerodynamic performance, improves efficiency, and extends its service life.

Development of a Building Simulation Model for Indoor Temperature Prediction and HVAC System Anomaly Detection

In order to reduce global energy consumption, energy-efficient, green and smart buildings have to be built. In addition to the application of other energy efficiency measures, an effective management of HVAC systems is required. High quality management and control of these systems ensures optimal occupant comfort levels, proper operation, rational energy consumption, and a positive impact on the environment. This is especially important for large buildings with complex systems such as hotels. As a contribution to the creation of appropriate tools for the management and control of HVAC systems in smart buildings, this paper presents the results of the current development of a detailed dynamic simulation model based on data collected from a smart room system in a hotel in Zagreb, Croatia. The smart room system, which is integrated into the hotel's building management system, provides historical data on set and current room temperatures, room occupancy schedule, window opening, fan coil operation status, fan rotation speed, valve opening, and operating mode with a time step of 5 minutes. The simulation model based on the TRNSYS software uses a part of the available data and calculates the current internal room temperatures. A comparison of the predicted and measured temperatures at each time step showed that the deviations are within the acceptable limits. The final objectives of the model development are the identification of anomalies in the operation of the HVAC system and the optimization of its operation with the aim of reducing energy consumption.

On the Flow Physics During the Transition of a Variable Pitch Fan From Nominal Operation to Reverse Thrust Mode

Abstract The flow field during the transition of variable pitch fans (VPFs) from nominal operation to reverse thrust mode at typical “Approach Idle” engine power setting and aircraft touchdown speed of 140 knots is described in this work. An integrated airframe-engine-VPF research model that features a future 40,000 lbf geared high bypass ratio engine installed on a twin-engine airframe in landing configuration is used to explore the flow field in a fully transient unsteady Reynolds-averaged Navier–Stokes (URANS) simulation with imposed wall motion. A novel methodology that implements an adaptation of a mesh displacement equation to mimic the fan blade airfoil rotation is developed. The implementation of this method with gradual, small-step deformation along with an automated mesh update routine enables a high quality, near “real-time” simulation of the complete transition. The flow field during transition is characterized by the evolution from full typical forward flow through the engine to the development of massive recirculation regions at the feather pitch setting and finally to development of a reverse flow from the bypass nozzle to the fan passages. In the paper, the transient development of the various flow features through different stations of the engine flow path apropos the fan blade airfoil rotation to reverse thrust mode are discussed in detail. Also, the temporal development of the mass flow ingested through the engine, airframe decelerating force, and distorted flow at the core engine inlet are described. A hitherto unresolved fan power peaking during the middle of the transition and higher power requirement at reverse thrust mode is captured. The effect of fan rotational speed in terms of engine power setting and the aircraft touchdown velocity on the transition flow physics is explored. A comparison of this fully transient approach with discrete steady-state runs for different stagger angle settings is presented. The flow physics during transition to reverse thrust mode as described in this study is critical in understanding the feasibility of using VPF for reverse thrust in future aircraft. The new capability to study the transition in a fully transient simulation can be used as a design development aid to define design and control characteristics of the reverse thrust VPF.

Novel performance enhancement of straight blade vertical axis wind turbines through cross-flow fan integration

In this study, a novel technique for enhancing the output power of Vertical Axis Wind Turbines (VAWTs) is introduced through the integration of a cross-flow fan (CFF) for active flow control, a first-of-its-kind approach. The CFF, positioned on the airfoil's trailing edge, employs suction to regulate flow separation. A thick airfoil with a 35% thickness-to-chord ratio is utilized to accommodate the CFF. A VAWT, featuring a diameter of 1 m and a height of 0.5 m, is designed, fabricated, and subjected to experimental testing in a wind tunnel. Additionally, a standard NACA 0018 wind turbine with identical dimensions and solidity is manufactured for performance comparison purposes. A custom test rig is developed to measure turbine output, encompassing a fixation mechanism, torque measurement system, and a mechanical brake mechanism for load variation. The impact of the CFF on the wind turbine performance is investigated by measuring turbine static torque due to the fan, fan motor power consumption, turbine torque, and rotational speed across various wind speeds. Power assessments are conducted to estimate the real turbine power increase, taking into account the power consumed by the fans. A fan map is generated to determine the optimal conditions and rotational speeds for fan operation.

A Three-Dimensional Body Force Modeling of Fans in Windmilling Condition and Its Application

To investigate the aerodynamic characteristics of the fan in windmilling conditions, a new body force model with the fan rotational speed prediction model was developed. The fan rotational speed prediction model was built based on the balance of fan output torque and resistance torque. The rotational speed of the fan spool can be iteratively solved simultaneously with solving the governing equations without requiring mass flow rate or other inputs. The comparison with the experimental results shows that using the body force model can accurately predict the rotational speed of the fan spool under different operating conditions. The radial distribution of flow parameters can be obtained. Moreover, numerical simulations of the fan under different circumferential total pressure distortion inflow conditions were conducted using the body force model. The results show that, unlike the design point and non-design point at which the fan operates normally, the high radius region of the fan is in the “turbine mode” while the low radius region is in the “compressor mode” under windmilling conditions. The different effects on the longitudinal vortex in the two regions deepen and alleviate the circumferential distortion, respectively. There are strong circumferential and radial pressure gradients at the junction of the distortion-affected zone and the non-distortion-affected zone, adding additional mixing losses.

Evaluation of the free-windmilling rotational speed of a damaged wide-chord fan rotor

The windmilling imbalance condition occurs after engine shut-down due to fan blade loss, but the engine continues to rotate under aerodynamic forces. This condition can induce undesirable structural excitation throughout the engine and airframe. Especially in the progression of larger high-bypass-ratio fans with fewer blades with larger chords, the excitation is considerably greater and is directly determined by the fan rotational speed. The aim of this study is to explore the windmilling flow through damaged fan rotor numerically according to the zero-torque characteristic, and to develop a prediction method of the windmilling rotational speed of damaged fans. An idealized span-damaged type is introduced to examine the effect of blade-to-blade flow interaction on the rotational speed of fans with various degrees of damage. In full-annulus simulations, whenever the damage of a single blade reaches 35%, the positive torque of the damaged blade reaches its maximum value, and the fan rotational speed instead reaches a new minimum. The results also show that the radial flow profiles at the rotor outlet are independent of airflow and can be determined using only the geometry of the damaged fan. This indicates the self-similar nature of the intra-stage flow. According to numerical results, a speed similarity coefficient of damaged fan is identified, and the dynamic pressure at the damaged fan outlet is the appropriate scale for the stagnation pressure loss across the rotor. Further, the engine is regarded as a finite number of variable cross-section frictional ducts, which facilitates the construction of a total stagnation pressure-loss model, allowing the windmilling airflow for any flight Mach number to be obtained. Finally, this study proposes a mathematical model to predict the windmilling rotational speed using the damaged fan speed similarity coefficient and the one-dimensional windmilling airflow function. The model can be applied to the early stages of high-bypass turbofan development and can be used to evaluate the safety characteristics during engine windmilling operations.

Instrumentation improvements for NGV aerodynamic characterization at high Mach numbers

One of the most important new engine concepts is the Geared turbofan. In these engines a gear box allows the decoupling between fan and turbine rotational speeds. As a consequence, the separate aerodynamic optimization of both components becomes possible leading to an increase in engine bypass ratios, higher propulsive efficiency and lower specific fuel consumption. The multi-stage intermediate pressure turbine (IPT) is one of the key parts of the thermodynamic cycle in geared turbofan architectures. During the characterization of a LPT NGV row, it is important to have detailed pressure losses measurements as accurate as possible. Because of the aerodynamic differences with conventional low pressure turbines (LPT), this becomes mandatory when the NGV is designed for an IPT. The main error sources are related to circumferential anisotropy, to repeatability of US and DS measurements, to effects of instrumentation in 2D losses and to static pressure measurement in the probe environment.

Determination of the model of a powered air-purifying respirator for researching its operational modes

Purpose. Justification of technical decisions when creating an experimental equipment of a powered air-purifying respirator (PAPR), development of a research system, planning and conducting an experiment, determining the structure of the object and its parameters, confirming the adequacy of the obtained simulation model of the PAPR to the control object in accordance with the conditions of the technological process. Methodology. The research was carried out on experimental equipment by means of an active experiment. It is proposed to use a sensor with an analog output and a controller for data registration to control the pressure. By varying the rotation speed of the fan, the value of the pressure in the respirator mask was determined. Structural and parametric identification and verification of the obtained model for adequacy to the control object according to the Fisher criterion were carried out on the basis of the obtained data. Findings. Based on the results of the study, it was established that the PAPR is an asymmetric object according to the "fan rotation speed - pressure in the mask" channel. The processes of pressure increase and decrease correspond in form to exponential functions and can be described by aperiodic links of the first order with different time constants. Based on the analysis of the structure of the control object, a corresponding asymmetric model was created in which aperiodic links are represented in the state space. Theprocess time constants and amplification factor of the model were determined by parameter estimation. The adequacy of the obtained simulation model to the control object was confirmed by Fisher's criterion. Originality. For the first time, a continuous transfer function of a PAPR was obtained in the form of a complex of two firstorder aperiodic links with different time constants. Practical value. A universal method of obtaining simulated models of PAPRs by using the developed experimental equipment and simulation environment of the MATLAB. The obtained simulation model of the PAPR allows to research its operating modes in order to determine the requirements for the control system and its further synthesis using various regulators.

Analisa Kebutuhan Energi Termal Pada Kotak Pengering Biji Kopi Arabica yang di Isolasi dengan Aluminium Foil

The experiment test was carried out to obtain the composition of the caloric quality needed to determine the water content and the mass amount of coffee beans when they were dried by utilizing the sun's heat. Heat transfer processes by convection, conduction and radiation play an important role in the drying process with heat quality. Ambient temperature data of 350C with a constant fan rotation speed of 1.0m/s. The duration of the test is 5 days where the initial sample weight is 5000gr with the final result being a water content of 12-15%, with a duration of testing per day for 10 hours starting at 08.00-18.00Wib. The final drying weight of coffee beans for 5 days is: 2500.21gr with an initial weight of 5000kg. The temperature difference around the box is 31,110C. heat weight to evaporate water content Qh= 65.6058.kJ. and the heat required in heating the Coffee beans is 72,839 kJ. The ability to dry 5000gr of coffee beans requires total heat: 138.43kJ with a drying box volume of 8.88m3.

Nonlinear Modeling of an Automotive Air Conditioning System Considering Active Grille Shutters

This paper expands upon the state of the art in nonlinear modeling of automotive air conditioning systems. Prior models considered only the effects of the refrigerant compressor and the condenser fan. There are two new aspects included here. First, we create a mathematical model for front-end underhood airflow, considering vehicle speed, condenser fan rotational speed, and active grille shutter position. In addition, we present a new model for the power consumption of the vehicle associated with aerodynamic drag caused by underhood flow, as well as a fan power model which accounts not only for changes in rotational speed but also changes in flow rate. The models developed in this paper are coded in MATLAB/Simulink and assessed for various vehicle driving conditions against a higher-fidelity vehicle energy management model, showing good agreement. By including the active grille shutters as a controllable actuator and the impact of underhood flow on vehicle drag and fan power consumption, control schemes can be developed to holistically target reduced energy consumption for the air conditioning system and, thus, improve the overall vehicle energy efficiency.

Effect of ceiling fan in mitigating exposure to airborne pathogens and COVID-19

Ceiling fans are the ubiquitously used electrical appliance in indoor spaces that affect the local airflow pattern and, consequently, transmission of airborne pathogens and respiratory droplets. This study numerically investigated the effect of airflow induced by the ceiling fan and ventilation rate on aerosol distribution to mitigate exposure to airborne pathogens and COVID-19. A full-scale room with a ceiling fan, natural ventilation and an occupant was modelled through transient computational fluid-particle dynamics (CFPD). To analyze the relationship between the ceiling fan rotation speed and the aerosol distribution, a ceiling fan was operated with 160, 265 and 365 revolutions per minute (RPM). The effect of the ceiling fan on particles was analyzed for particles of different sizes. The increasing ceiling fan rotation speed, the percentage deposition of the aerosol particles with diameters &gt;40 μm was increased. The effect of different ventilation rates on aerosol distribution was evaluated. The increased ventilation rate, the percentage of the total aerosol particles flushed out was increased. The effectiveness of the mask in mitigating the exposure risk of airborne pathogens was also investigated. In combination with the natural ventilation and mask, the ceiling fan was demonstrated to have the potential to reduce airborne pathogen transmission in indoor spaces.

Koopman-Based Modeling of an Open Cathode Proton Exchange Membrane Fuel Cell Stack

Accurate modeling is crucial for the effective design and control of fuel cell stacks. Although physics-based models are widely used, data-driven methods such as the Koopman operator have not been fully explored for fuel cell modeling. In this paper, a Koopman-based approach is utilized to model the thermal dynamics of a 5 kW open cathode proton exchange membrane fuel cell stack. A physics-based model is used as the baseline for comparison. By varying the cooling fan rotational speed, the dynamics of the fuel cell stack were measured from the low load of near 0 kW to about 5 kW. Compared to experimental results, the steady-state absolute errors of Koopman-based models are within 3%. Additionally, once given sufficient dimension, the development effort required for the Koopman-based model is relatively low compared to the traditional physics-based approach, while still achieving a high level of accuracy. These findings suggest the Koopman operator may be a suitable alternative approach for fuel cell stack modeling that enables the development of more accurate and efficient modeling methods for fuel cell systems and facilitates the implementation of the linear optimal algorithms.

Inlet Gap Influence on Low-Frequency Flow Unsteadiness in a Centrifugal Fan

In this study, unsteady low-frequency characteristics in a voluteless low-speed centrifugal fan operating at a high mass flow rate are studied with improved delayed detached eddy simulation (IDDES). This study is motivated by a recent finding that the non-uniformly distributed pressure inside this type of fan could be alleviated by improving the gap geometry. The present simulation results show that the velocity magnitudes of the gap have distinct low and high regions. Intensive turbulent structures are developed in the low-velocity regions and are swept downstream along the intersection between the blade and shroud, on the pressure side of the blade. Eventually, the turbulence gives rise to a high-pressure region near the blade’s trailing edge. This unsteady flow behavior revolves around the fan rotation axis. Additionally, its period is 5% of the fan rotation speed, based on the analysis of the time history of the gap velocity magnitudes and the evolution of the high-pressure region. The same frequency of high pressure was also found in previous experimental measurements. To the authors’ knowledge, this is the first time that the trigger of the gap turbulence, i.e., the unsteady local low velocity, has been determined.

Event-Based Angular Speed Measurement and Movement Monitoring.

Computer vision techniques can monitor the rotational speed of rotating equipment or machines to understand their working conditions and prevent failures. Such techniques are highly precise, contactless, and potentially suitable for applications without massive setup changes. However, traditional vision sensors collect a significant amount of data to process and measure the rotation of high-speed systems, and they are susceptible to motion blur. This work proposes a new method for measuring rotational speed processing event-based data applied to high-speed systems using a neuromorphic sensor. This sensor produces event-based data and is designed to work with high temporal resolution and high dynamic range. The main advantages of the Event-based Angular Speed Measurement (EB-ASM) method are the high dynamic range, the absence of motion blurring, and the possibility of measuring multiple rotations simultaneously with a single device. The proposed method uses the time difference between spikes in a Kernel or Window selected in the sensor frame range. It is evaluated in two experimental scenarios by measuring a fan rotational speed and a Router Computer Numerical Control (CNC) spindle. The results compare measurements with a calibrated digital photo-tachometer. Based on the performed tests, the EB-ASM can measure the rotational speed with a mean absolute error of less than 0.2% for both scenarios.