The present study investigates the characteristics of a phased-array ultrasound unit as a flow control actuator. Acoustic streaming is driven by the intense ultrasound through the viscosity. The ultrasound phased array unit AUTD3, which consists of many ultrasound transducers arranged in a rectangular shape, can generate various focused ultrasound fields, e.g., the Bessel and focused beams, and the beam parameter can be configured. The Bessel and focused beams were evaluated using thermal imaging measurements. The mesh screen was exposed to the ultrasound beam, and the intensity of sound pressure fluctuations was evaluated from the instantaneous temporal temperature gradient at the sound emission. The three-dimensional spatial distributions of the sound pressure fluctuations in the beam were evaluated at different distances between the ultrasound transducer unit and the mesh screen. It was revealed that the focused beam produced a maximum sound pressure of 4.49 kPa at the focal point. The Bessel beams showed strong sound pressure fluctuations, i.e., exceeding 2 kPa at the beam center, in a wide range of distances.

Insects and bioinspired micro air vehicles (MAV) gain lift by flapping their wings, on which a Leading Edge Vortex (LEV) is formed. Dynamic increases in angle of attack on their wings cause the formation of LEV on the wing surface. The LEV provides additional lift and therefore more efficient flight can be achieved by promoting the growth of the LEV and delaying its detachment. In this study, we attempt to augment the growth of LEV on a pitching NACA 0015 aerofoil using a dielectric-barrier-discharge plasma actuator (PA) placed 88% of chord length from the leading edge. The effect of the control is evaluated by the surface pressure measurement. The lift coefficient was successfully increased by 9.4% on average over time by actuating PA from the beginning of the motion. It was also suggested that actuating a PA at a trailing edge of the aerofoil may act in two ways: (1) inducing virtual camber and (2) augmenting LEV growth. This study is a first step towards future feedback control of LEV dynamics, which adapts to unsteady flow conditions.

In this study, we performed deep reinforcement learning-based flow control using plasma actuator in a 3D CFD to improve the control system of a wind tunnel experiment. To achieve this, we analyzed the control strategy based on the trained controller using detailed visulizations of the flow field and control history. The target flow field is around the NACA0015 airfoil, and the flow condition is Re = 6.3 × 10⁴, AoA = 14°, which is over 3° higher than the stall angle. As a result, we confirmed that the same control strategy was trained in the 3D CFD as in the experiment. Moreover, the trained controller achieved a higher L/D than conventional predetermined controls by combining F⁺ = 1 and F⁺ = 6.

When an ultrasonic pulse reflects from a solid sphere, the echo waveform is determined by the size, position, and acoustic impedance of the sphere. By analyzing the ultrasonic pulse echo, it is expected to estimate the information about solid sphere. To evaluate the feasibility of its estimation, echoes from a solid sphere fixed in a water tank were measured and analyzed while changing its relative position from the transducer. Different sized glass and steel sphere were used in the experiment. As a result, an echo comprises two parts; one is the first reflection which is reflected from the front surface of a solid sphere, and the other is complex second reflection. It seemed that the second reflection included multiple reflection inside a sphere. We extracted the peak amplitude of these first and second reflected waves. We found that the amplitude ratio between two reflected waves showed a good correspondence with the material of a sphere. By correcting the amplitude to account for the attenuation of ultrasonic pulse in water, it is also found that it was possible to estimate the size of a sphere after eliminating the effect of distance between the transducer and a sphere.

The characteristics of water-silicon oil two-phase flow in a microchannel with a rectangular cross section of 1.0 mm height × 1.0 mm width were experimentally investigated. In order to understand the effects of fluid viscosity and channel wall wettability on slug flow in a microchannel, the viscosity of the continuous phase was changed and the channel walls near the fluid mixing zone were coated with a water repellent. The contact angles were approximately 108° and for the non-coating surface and 140° for the coating one. In the experiments, droplet length, droplet velocity, number of slugs passed and pressure drop were measured. It was found that, the droplet length decreased with coating water repellent and with increasing viscosity of the continuous phase. The pressure drop was affected by the viscosity of the continuous phase.

In order to develop an in-line small hydroturbine that can generate 300W at a small flow rate of 3l/s, we adopted a contra-rotating rotors to achieve both miniaturization and high efficiency of our hydroturbine in this study. A centrifugal rotor that can be applied to small flow rates and high heads is used for a front rotor, and a hybrid rotor that combines a mixed flow rotor and an axial flow rotor is used for the rear rotors with the propose of recovering the same head as the front rotor. In addition, a volute was employed to inject pre-swirl into the front rotor. In this study, a small flow rate turbine with a design flow rate of 3l/s was designed, but its efficiency is lower than that of larger turbines. In order to investigate the cause of this low efficiency, a numerical analysis was conducted focusing on the clearance behind the main plate.

In order to effectively utilize unused hydraulic resources in irrigation channels, and simple water supply systems, it is essential to improve the performance and reduce the size of small hydroturbines. In this study, we adopted a contra rotating rotors that efficiently recovers energy by using two rotors, with the aim of achieving both high performance and compactness in a small hydroturbine. In previous studies, the front and rear rotors of this test turbine are connected by a spacer with four spokes, but the optimal axial distance of the spacer has not yet been clarified. Therefore, we conducted a numerical analysis to investigate the effect of the axial distance of the spacer on the performance of the test turbine (D50 model) with a diameter of 50 mm. In this paper, we focus on the performance characteristics and internal flow of four models with different axial distances of the spacer, and report the results.

The swirling flow with cavitation can cause the cavitation volume fluctuation in a draft tube of a hydro turbine at the full load operating conditions, causing pressure pulsations with flow rate fluctuations known as cavitation surge throughout the hydraulic system. The cases that predicted the phenomenon qualitatively using the CFD analysis have been reported previously, whereas the methods to predict the cavitation volume and the fluctuation frequency in the cavitation surge condition quantitatively have not yet been established. Therefore, in this study, the influence of the boundary conditions on the prediction accuracy of the cavitation surge was investigated in CFD analysis. The frequency of the cavitation surge was calculated to be lower than the experimental results because cavitation surge causes flow fluctuation throughout the hydraulic system, but only part of the hydraulic system was modeled and the boundary condition was fixed in CFD analysis. These results imply that the entire hydraulic system must be modeled to improve prediction accuracy. Thus, in this study, the entire system was modeled in 1D and coupled with CFD. This coupled simulation improved the prediction accuracy of the frequency, and the effectiveness of the coupled simulation considering the entire hydraulic system was clarified.

Radical changes in fluid properties occur near the critical point, which could trigger flow instability in cryogenic fluid machinery for a hydrogen energy-based society. Therefore, more detailed investigations are necessary to understand this instability phenomenon. In this investigation, we conducted CFD analysis of nitrogen flow in a Venturi tube simulating the experimental apparatus that could perform a flow test under transcritical and supercritical conditions. Physical properties of nitrogen were extrapolated by the dataset based on the Helmholtz energy equation of states. In addition, the grid resolution was carefully investigated to grasp fluid properties change in the modeled Venturi tube. In the simulation, we simulated the flow using a coupled solver for compressible CFD simulation for several conditions: Liquid, Supercritical, and Transcritical conditions. Moreover, we also used a segregated solver for the Transcritical condition for the comparison assumed the incompressibility. The simulation results of the Transcritical conditions indicated a more radical change in density and other physical properties than the other conditions, suggesting a flow instability near the critical point. Compared with the incompressible simulation, a temperature diffusion was observed near the critical point, supposed to be induced by sudden changes in specific heat. This research enabled us to establish a simulation method for predicting abrupt changes in physical properties near the critical point.

The camber line of the inducer is important in designing the inducer because it has a large effect on the suction performance and the state of cavitation. In general, the straight section with a constant blade setting angle is maintained up to the inlet throat, and the camber line is curved beyond that point, but there is no clear basis for this. In this study, four types of camber lines with different lengths of the straight section were designed, and a multiphase unsteady analysis was performed on two-dimensional cascades assuming inducer blade tips with each camber line. The effects of the difference in camber line on suction performance and unsteady cavitation behavior were then analyzed. As a result, it was found that the relationship between the length of the flat plate blade and suction performance varies depending on the flow rate. At the design flow rate, the suction performance was best when the flat plate blade was 20% of the chord length. At low flow rates, the suction performance was best when the shape was maintained up to the throat. In addition, numerical simulations showed that the cascade with shorter flat blades resulted in faster cavitation growth and a wider range of cavitation instabilities.

The objective of this paper is to clarify the effect of different inducer outlet angle from view of the suppressing cavitation instability. Pumps for transferring liquefied natural gas require low NPSHR and stability over a wide flow range. Low-solidity fan-type inducers installed to improve suction performance, cavitation instability flow phenomena have been observed at low flow ranges. In this study, for the purpose of establishing design guidelines for low solidity inducers, the effect of outlet angle on cavitation instability phenomena was investigated with the fixed inlet angle of the inducer.

Cavitation in industrial pumps is caused increasing noise and vibration, in addition to decreasing pump instability. Therefore, it is important to predict the occurrence of cavitation at the design and test stage. Noise is often used to observe condition of cavitation and pump. In this study, an air-borne microphone was set near the inducer and noise was measured as part of the establishment for a cavitation evaluation method using noise data. The visualization test using an acrylic casing and a high-speed camera was conducted to observe the cavitation behavior. From these results, the relationship between noise and various cavitation phenomena was investigated. Experimental results showed noise was decreased when sheet cavitation had occurred at the entire flow path around the inducer, and the noise level was decreased in wide bandwidth above 1 kHz. However, there was no significant difference in the specific frequencies, regardless of the cavitation instability phenomenon.

Small side thrusters installed on small vessels are often operated at high rotational speed near the draft surface and are therefore prone to cavitation. Therefore, it is important to clarify the occurrence of cavitation and its effect on thrust performance at various speeds, but there have been few studies on this subject. In this study, we conducted experiments using a high-speed camera to visualize cavitation and measure thrust, and cavitation analysis on a small side thruster with a propeller diameter of 190[mm]. This paper reports on the effects of cavitation on performance and internal flow in the region of cavitation number with increased thrust.

The operating range of centrifugal pumps at non-design points is greatly limited by unsteady phenomena such as diffuser rotation stall (DRS), which is a problem in the industrial field. To expand the operating range of a centrifugal pump, a hole was drilled near the front edge of the diffuser vane, and the DRS suppression effect of the jet flow passing through the hole was experimentally investigated. Although the DRS suppression effect of the jet flow at the leading edge of the vane was confirmed, the hole was not examined in detail. In this study, the internal flow was investigated by numerical fluid dynamics analysis to examine more effective holes.

The internal flow at low flow rates for a diffuser with a hole near the vane leading edge was found to cause DRS when the hole was smaller than the core of negative pressure due to the detached vortex generated at the diffuser vane leading edge. Increasing the diameter of the hole near the leading edge of the vane increases the DRS suppression effect, but the pump head is significantly reduced.

In industrial turbopump design, numerical analysis using the Reynolds-averaged Navier-Stokes equations is often used because it is less expensive in terms of computation. However, a major challenge is that the results do not exactly match the real internal flow, as turbulence models are applied in the calculations. This gap becomes especially important when dealing with complex flow phenomena, where understanding the differences between actual behavior and numerical results can help create better design guidelines. In this study, the critical flow lines were visualized using a multi-color oil-film technique for two vaned diffusers with different vane inlet angles, both of which are known to cause diffuser rotating stall (DRS). The visualization showed that in the model with a smaller vane inlet angle, rotation occurred immediately after stalling, while in the model with a larger vane inlet angle, rotation did not occur despite stalling. This suggests that the internal flow leading to DRS varies depending on the diffuser model.

It is known that in centrifugal pumps, when the specific speed is below 100, leakage loss and disk friction loss increase, causing a significant decrease in efficiency. On the other hand, mini centrifugal pumps with a diameter of 100 mm or less are thought to be more affected by disk friction loss than conventional centrifugal pumps with a diameter of 100 mm or more. Therefore, we evaluated disk friction loss for two types of mini centrifugal pumps with different impeller diameters and a specific speed of around 200. In this study, we investigated the effect of the blade outlet angle of a mini centrifugal pump on disk friction loss.

We investigated complex motion of small particles in a rotating flow driven by a pair of corotating disks mounded in an enclosure equipped with a partial shrouhd opening. The flow is a model of hard disk drive (HDD) used for external storage device. In HDD, small particles discharged from mechanical parts levitats in the wokring fluid and they may cause damage on the disk and/or magnetic head. In the present study, flow visualization expetiments were performed to elucidate the complex motions of small particles in the highly unsteady and three-dimensional flow formed in a HDD model. Regractive index matched system was used for providing unobstracted view of the whole flow field. For particles, nearly neutrally buoyant particles were seeded into the flow. Particle trajectories were observed by tracking the individual particles and their two-dimensional motion was analyzed in the polar cooridnate in the plane parallel to the disks. As a result, particles tend to pass through certain positions in the plane. Initially, the levitating particles flow towards the outer region of the disks due to the centrifucal force, hit against the shrouded wall, and are reflected back into the inner region of the disk at certain circumferential angles. The statistical analysis revealed the trajectory tendency of particles passing through certain positions with higher frequencies compated to the other positions in the two dimensional plane.

Rotational flows driven by stacked disks in an enclosure as seen in fluid machinery and hard disk drive (HDD) exhibit complex three-dimensional behavior. In experiments, the flow velocities are accessible in the planes parallel to the disk surface, but direct evaluation of the ones perpendicular to the disk surface remains difficult. In this study, we attempted to reconstruct the axial velocities based on the integration of the mass conservation using the in-plane velocity fields acquired at multiple planes parallel to the disk surfaces. For the velocity measurements, we applied two-dimensional, two-component particle image velocimetry (PIV). The averaged axial velocities were reconstructed through the numerical integration of the axial velocity gradients, which were obtained through the numerical differentiations of the in-plane velocity gradients of the averaged velocity fields of the PIV data. The method was applied to a rotating flow driven by the stacked disks mounted in a non-axisymmetric enclosure equipped with arm assembly. The flow was a 2.25 times scaled model of hard disk drive (HDD) for information storage. The model allows an optical access for flow visualization and PIV measurement with the refractive index of the working fluid matched to that of the resin of the transparent HDD model. The PIV measurements were performed at 21 planes in the flow at the Reynolds number of 7.4 × 10⁴ corresponding to 5400 rpm in a 3.5-inch HDD. Based on the proposed scheme, the averaged axial velocities were reconstructed based on the method. They were examined at different circumferential angles. The reconstructed velocity fields revealed the existence of secondary flow structure in the region downstream of the arm. The reconstruction of the axial velocity provides a method to investigate the complex three-dimensional structure of the flow.

We investigated flow phenomena using a refractive index-matched model, scaled to 2.25 times the size of an actual 3.5-inch HDD. The model focused on the interaction between the primary moving components: the disk and arm. The rotating disks generates centrifugal forces that drive fluid radially outward, creating a pressure gradient. This setup was studied across three measurement planes, with specific attention to the flow fields between two intermediate planes located between the disks and the arm, relative to the disk-to-disk middle plane. We analyzed in cylindrical coordinates fixed at arm isolation angles of α = 20°, 32°, and 44°, which define the separation of flow between the disk and the shroud opening region. Our findings reveal that the inflow velocity from the shroud opening significantly impacts the velocity distribution around the disk region across all measurement planes. The hub-arm region induces an accelerated flow, affecting the solid body region around the hub for all arm insertion angles. Additionally, the magnitude of the velocity highly depends on the arm's insertion angle across the disk region. The arm isolation angle further influences these dynamics, leading to measurable changes in momentum exchange between the disk and the surrounding flow, particularly in the mid-plane and intermediate regions between the disks and the arm.

Evaluating the effect of wind on drone motion is important for improving stability and controllability. In this study, we aimed to evaluate the effect of a downward jet on drone attitude control. In the experiment, a jet with a nozzle diameter of 1.6 mm and an exit velocity of 45 m/s was directed from above at a flying drone. Based on the equation of motion for rotation, the time change in angular velocity was calculated from the torque calculated from the jet's wind pressure and propeller thrust. The calculated angular velocity was roughly consistent with the measured value, demonstrating that it is possible to predict the change in angular velocity of a drone from wind strength.

The shape of a ducted fan mainly used under hovering condition was optimized using parametric modeling CFD analysis. Parametric CAD modeling was used to generate the shape of the fan and duct using multiple parameters, and it was combined with automatic meshing and automatic CFD optimization method. As a result, it was shown that the thrust of optimized shape under hovering condition was higher than that of baseline. And at the same time, the side drag force of optimized shape under crosswind condition was lower than that of baseline. The obtained optimized design has a thick lip shape which reduces the curvature of leading edge of duct and reduces separation region under crosswind condition. It is clear that the design concept of the ducted fan mainly for hovering operation condition is quite different from that of the ducted fan mainly for cruising operation in general aero engines.

In this study, a numerical analysis using the Lattice Boltzmann Method and noise measurements were performed on a test fan equipped with a Multi-Slotted blade that mimics a Bird's Wing Tip geometry. The tested fan is a small axial type for server cooling, equipped with 5 rotor blades and 7 rear-mounted stated blades and covered with a casing. The LBM analysis confirmed the complex flow field inside the casing and clearly visualized the blade tip leakage vortex. It was also confirmed that the non-axisymmetric bell-mouth shape have a significant effect on the flow field near the blade tips and the noise source term. Downstream of the rotor blade, a Multi-Slotted blade was found to attenuate the blade tip leakage vortex compared to the base model through the static pressure distribution results. According to noise measurements, first order BPF noise in the Multi-Slotted blade was reduced by approximately 5dB compared to the base model. The overall value in the one Multi-Slotted blade was reduced by approximately 0.9dB compared to the base model.

Carbon nanotube (CNT) composite paper has been proposed and is expected to be applied to micro-power generation. The composite paper generates electricity when a drop of pure water or an inorganic salt solution such as hydrochloric acid penetrates into the composite paper. However, the mechanism of power generation has not been fully clarified. In this study, an ion transport model in CNT composite paper was established and its micro-power generation characteristics were clarified by time-dependent one-dimensional numerical simulation. Results showed that the electromotive force is generated by the space charge generated near the liquid-composite paper interface. Furthermore, it was shown that under low flow velocity conditions, the space charge near the interface increases due to polarization caused by diffusion, which results in an increase in electromotive force. It was also clarified that higher concentrations of hydrochloric acid enhances output power.

Cellulose nano-fiber (CNF) is a fundamental component of wood fiber. The single cellulose filament by assembling CNF shows excellent mechanical properties by improving the CNF orientation inside the filament. In this study, The CNF with silver nanoparticles was fabricated by mixing of CNF dispersion with Tollen’s reagent at 80 oC for 2 hours. The prepared CNF dispersion with nano particles loading was then introduced into an apertured flow channel with/without electric field. The CNF in the flow channel was aligned along the filament axis by the electric field and elongational flow formed in an apertured part. This study successfully fabricated the antibacterial filaments with silver nano particle loading. Furthermore, the effects of the mixture ratio of CNF dispersion with Tollen’s reagent, and applying electric field on the mechanical properties of the filament were clarified. As a result, the larger the content of the silver nano particles is, the higher the ultimate tensile strength of the filaments becomes. CNF orientation degree was improved under lower mixture ratio due to the lower viscosity of the dispersion allowing the CNF to rotate more with untangling. However, when the content of silver nano particles was rather high, the filament was not fabricated due to weaker hydrogen bonds between CNFs with excessive inclusion of silver particles. It was also elucidated that applying electric field effectively improves the ultimate tensile stress, elastic modulus, and toughness of the silver nano particles-loaded filaments even under high mixture ratio conditions.

Biological and macromolecular flows are multilayered flows, and microcirculation exhibits complex flow characteristics due to erythrocyte deformation. In addition, erythrocyte deformability is reduced by various diseases. A method for evaluating erythrocyte deformability is to image the shape change from the viscous stress generated by the velocity gradient between two walls of a vibrating plate. The purpose of this study is to tomographically detect flow characteristics using Doppler Optical Coherence Tomography. The velocity distribution between the oscillating plates was tomographically visualized for a flow with a blood cell concentration equivalent to that of a living body. The results showed that the shear velocity decreased as the shear rate increased, and the shear velocity was visualized as a shear-slicing behavior.

The clinical application of autologous cartilage transplantation requires the intraoperative evaluation of mechanical properties around the harvested cartilage. Biorheological properties of cartilage have never clarified exhaustively, esptially in terms of pore fluid pressure generated by tissue consolidation. In this study, the biorheological mechanism of cartilage is investigated on the basis of simulated pore fluid pressure generated by consolidation effects during compression. As a result, the spatio-temporal distribution of pore fluid pressure was visualized tomographically. The generation of pore fluid pressure, which is dependent on the cartilage tissue structure, is thought to play a significant role to the biorheological properties.

Pancreaticobiliary maljunction or high confluence may cause pancreatic juice reflux into the biliary tract. However, the mechanism of the reflux is still unclear. This study has developed a one-dimensional mathematical model for the pancreaticobiliary flow system and simulated simultaneously the flow and the mass transport during bile refilling into the gallbladder, taking into account the mixing of the bile and the pancreatic juice and viscosity changes caused by the water absorbing of hepatic bile juice in the gallbladder. The effects of morphological parameters of the hepatobiliary and sphincter function on pancreatic fluid reflux were investigated. The viscosity changes due to both the water absorption in the gallbladder and mixing the bile juice and the pancreatic juice affected the pancreatic juice reflux, and the change of the length of the common channel within the region of the sphincter of Oddi was more sensitive.

In recent years, there has been an increasing need to improve air quality in living spaces such as homes, offices, hospitals, etc. In this study, we developed a high-speed deodorizer using a plasma actuator (PA) and evaluated its deodorizing performance against tobacco odor, toluene gas, and ethylene gas. The PA generates plasma-induced flow through dielectric barrier discharge, which draws odorous molecules into the plasma and decomposes them with OH radicals. In this study, we conducted deodorization tests in accordance with JEM1467 and compared the performance with commercially available filter-type deodorizers. The deodorization performance tests confirmed that the PA deodorizer meets the JEMA (Japan Electrical Manufacutures Association) standards for all five tested odorous molecules (ammonia, acetic acid, acetaldehyde, toluene, and ethylene). Notably, it demonstrated excellent decomposition and deodorizing performance for ethylene gas, which is difficult to deodorize through adsorption.

MHI has developed a liquid hydrogen pump for hydrogen refueling stations. This pump is a reciprocating pump that boosts low-pressure liquid hydrogen of 1 MPa or less to 90 MPa and enables high-speed and large-flow filling of large commercial vehicles such as buses and trucks. A failure of the liquid hydrogen pump directly leads to a decrease in the operating rate of hydrogen refueling stations, so high reliability is required. In order to verify and demonstrate the reliability of the pump, a reliability test was conducted for more than 900 hours. Especially, as a part of the reliability verification, fluid measurement of cryogenic high-pressure hydrogen was carried out.

The objective of this study is to realize the low NOx emission from a carbon neutral micro gas turbine engine utilizing high fidelity reactive flow simulation. In this paper, large eddy simulation (LES) with a turbulent combustion model using a generalized fluid interface mathematical model proposed by Oshima is applied to predict the combustor performance of a hydrogen micro gas turbine. The simulation of 23million nodes unstructured grid and 240,000 time steps is completed in approximately 10 days using 720 parallel cores (2400 node hours) of Osaka University super computer “SQUID”. The simulation results show that LES well predicted the unsteady behavior of the turbulent combustion flow in the combustor chamber and the combustor performance as well as the correlation between the equivalent ratio and NO production qualitatively.

Mitsubishi Heavy Industry Engine & Turbocharger has developed Electric Air Compressor for Fuel Cell, utilizing our expertise in high-speed rotation technology and mass production honed through turbocharger development to achieve an efficient two-stage supercharging capable of reaching 110,000rpm．This paper emphasizes the design of the intermediate piping connecting the low-pressure compressor to the high-pressure compressor．Through detailed flow analysis and pressure measurements in previous prototypes, it was shown that the shape of the intermediate piping contributes to a decrease in pressure ratio and aerodynamic efficiency in high pressure stage．To address this, we devised a J-shaped piping configuration and achieved performance improvement based on analysis and experimental measurements．

In train air conditioning systems, there is a demand for increased flow rate at the same rotational speed to improve cooling performance, energy efficiency, and noise reduction. However, the installation space for air conditioning equipment is limited due to vehicle height restrictions and the need to secure cabin space. This limited space results in a complex structure around the outdoor blower fan, with heat exchangers and flow path walls near the fan, making it difficult to increase the flow rate. In this study, topology optimization based on numerical fluid analysis was conducted on the flow path around the outdoor blower fan of train air conditioning equipment to maximize the flow rate. The solid region obtained from the optimization was finely distributed, so the essential improvement points indicated by the result are interpreted and converted into a designable shape. Characteristic shapes were extracted from the distribution of the solid region obtained by topology optimization, simplified, and reflected in numerical fluid analysis to compare the flow rate. It was found that adding parts around the motor could increase the flow rate. Furthermore, by performing parametric optimization and modifying the shape to be sheet metal processable, additional parts that balance increased flow rate and manufacturability were derived. To confirm the effect of the additional parts, the flow rate was measured using a half-size test machine that simulated the area around the outdoor unit of a train air conditioning system. As a result of attaching the additional parts, the flow rate increased by 5.8%, demonstrating the effectiveness of the flow rate increase in the experiment.