• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.491-498
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• 2004

Lift Fan Engines of JAXA's conceptual Jet VTOL aircraft have a very small bellmouse shape air intake, which make some differences in aerodynamic design of the blades. To obtain a better rotor or stator blade design, this paper performs a numerical analysis of the throughflow on a lift fan as a two-dimensional axisymmetrical flow. Based on the last report focusing on the air intake's influence on the throughflow, a more realistic bellmouse air intake case is treated to reconsider the influence on the throughflow by the small bellmouse air intake. Three work input patterns are tested to reduce some problematic influences on the throughflow or blade designs. The obtained result shows one of acceptable blade designs for the lift fan engine.

• Journal of Advanced Marine Engineering and Technology
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• 제31권6호
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• pp.768-776
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• 2007

In this study, axial vibration analysis has been conducted on a propulsion and lift shafting system for an air cushion vehicle using ANSYS code. The shafting system is totally flexible multi-elements system including wood composite material of air propeller. aluminum alloy of lift fan and thin walled shaft with flexible coupling. The analysis calculated the axial natural frequencies and mode shapes of the shafting system taking into account an equivalent mass-elastic model for shafting system as well as the three-dimensional models for propeller blade and fan impeller. Such a flexible shafting system has very intricate vibrating characteristics and especially, axial natural frequencies of flexible components such as propeller blade and impeller of lift fan can be lower to the extent that causes a resonance in the range of operating revolution. The results for axial vibration analysis are presented and compared with the results of axial vibration test for lift fan conducted during Sea Trial.

• 융복합기술연구소 논문집
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• 제9권1호
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• pp.25-30
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• 2019

Normal cranes cannot be used to move the fan inside the high-rise factories. Due to the size of the fan and safety accidents, there is a need for a structure capable of lifting and transporting. In this study, the safety of the structure was evaluated by considering the center of gravity of the fan and the effect of the fan being tilted up. An analysis of the buckling was performed by hand calculation. Nonlinear analysis was performed using ABAQUS to evaluate the safety of the structure. The safety factor for buckling is above 4.0 and the safety factor for stress is calculated to be 1.31 under the worst load distribution conditions.

• 한국항공운항학회지
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• 제30권2호
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• pp.1-6
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• 2022

Recently, the development of UAM, which was named by NASA as an alternative to solve the traffic and environmental problems caused by the rapidly progressing urbanization. When designing UAM, the location of lift fans greatly affects the core technology of the eVTOL type, distributed electric propulsion technology and aerodynamic performance of the vehicle. In this paper, a hybrid UAM model was designed using OpenVSP, an open source aircraft configuration modeling program, and aerodynamic analysis was performed according to the lift fans position change by the vortex lattice method. As a result, it is confirmed that the flight parameters and trailing wakes are stable by fixing the lift fan with the state rotated 0° to the flow direction of the aircraft during cruise flight. Also, OpenVSP is a suitable tool to be used in aircraft configuration modeling and design.

• 소음진동
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• 제6권5호
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• pp.661-669
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• 1996

Proposed is an aero-acoustic performance prediction method of axial fan. The fan aerodynamic performance is predicted by combining pitch-averaged quasi 3-D flow analysis with pressure loss models for blade boundary layer and wake, secondary flow, endwall boundary layer and tip leakage flows. Fan noise is assumed to be radiated as dipole distribution type, and its generation is assumed to be mainly due to the vortex street shed from blade trailing edge. The fluctuating pressure and lift on the blade surface are analyzed by incorporating the wake vortex stree shed from blade trailing edge. The fluctuating pressure and lift on the blade surface are analyzed by incorporating the wake vortex street model with thin airfoil theory. The aero-acoustic performance prediction results by the present method are in good agreement with the measured results of several axial fans. With the present prediction method, parametric studies are carried out to investigate the effects of blade chord length and spacing on the efficiency and the noise level of fan. In the case of lightly loaded fan, both efficiency improvement and noise reduction can be achieved by decreasing chord length or by increasing blade specing. However, when fan is designed at highly loaded condition, the noise reduction by increasing blade spacing penalizes the attaninable efficiency of fan.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.529-535
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• 2001

A centrifugal fan design code was developed and packaged together with iDesignFan／sup TM／ as new models. This code generate centrifugal forward curved and backward curved bladed impeller optimally. It also predicts the aerodynamic performance and the overall sound pressure level of the rotating fan by assuming steady blade loading. The overall sound pressure level is used as an input parameter from the third loop of the designing process to acquire the most silent fan for the given aerodynamic performance parameters. With this kind of inverse design concept used in the code, the period of designing a fan is significantly shortened. A centrifugal fan design code, developed in this study and included in iDesignFan／sup TM／, predicts the aerodynamic performance such as design flow rate and static pressure. The aerodynamic performance in the design and off-design conditions is calculated by using the mean line analysis. For the steady loading calculation, the lift force distribution in a blade is used.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.123.2-123.2
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• 2005

• 한국소음진동공학회논문집
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• 제18권9호
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• pp.952-960
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• 2008

Fan noise prediction method is presented for air conditioning, automobile and electronic cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(flow network modeling). Fan noise prediction method comprises two models for the discrete frequency noise due to rotating steady aerodynamic lift and blade interaction and for the broadband noise due to turbulent boundary layer and wake vortex shedding. Based on the fan operation point predicted from the FNM analysis results and fan design parameters, the present far noise model predicts overall sound pressure level and spectrum. The predictions for the flow distribution, the fan operation and the noise level in air cooling system by the present method are well agreed with 3-D CFD and actual noise test results.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.48-53
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• 2001

A centrifugal fan design code was developed and included in $DasignFan^{TM}$. This program generates forward -curved and backward-curved bladed centrifugal fan data. With the inverse design concept used in the code, the period of designing a fm, which has given aerodynamic performance with minimal acoustic noise, is significantly shortened.. A centrifugal fan design code, developed in this study and included in $DasignFan^{TM}$, predicts the aerodynamic performance by using mean-line analysis and various loss models. In the period of design a lift force distribution between pressure side and suction side of blade is calculated. And then it is used to calculate steady loading noise from the impeller.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.594-601
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• 1997

Propeller fans are commonly equipped in outdoor units of air-conditioners to provide effective cooling in a dried heat exchanger. A new design technique was developed to satisfy requirements of aerodynamic and aeroacoustic performance, which employs the intersection method of two cylinders for mean camber line. Three proto-types of propeller fan including Palm-Shaped, Highly-Swept(PSHS) fan (proto 3)were not only to provide low lift forces for dipole sound, but also to reduce the organized tip vortices interacting with the fan guide causing narrow-banded rotating instabilities. Cross-correlation technique was applied to study flow noise source characteristics for three proto-type fans designed. The cross-correlations between a microphone at far field and a hot-wire sensor at near field show that flows near hub region of proto 3 fan are less organized and the flow structures especially at high flow rate coefficients for proto 3 fan are less correlated with noise generated than other proto-types fans.