• Advances in aircraft and spacecraft science
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• v.2 no.1
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• pp.45-56
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• 2015

The attitude aerodynamic control is an important subject in the design of an aerospace plane. Usually, at high altitudes, this control is fulfilled by thrusters so that the implementation of an aerodynamic control of the vehicle has the advantage of reducing the amount of thrusters fuel to be loaded on board. In the present paper, the efficiency of a wing-flap has been evaluated considering a NACA 0010 airfoil with a trailing edge flap of length equal to 35% of the chord. Computational tests have been carried out in hypersonic, rarefied flow by a direct simulation Monte Carlo code at the altitudes of 65 and 85 km, in the range of angle of attack 0-40 deg. and with flap deflection equal to 0, 15 and 30 deg.. Effects of the flap deflection have been quantified by the variations of the aerodynamic force and of the longitudinal moment. The shock wave-boundary layer interaction and the shock wave-shock wave interaction have been also considered. A possible interaction of the leading edge shock wave and of the shock wave arising from the vertex of the convex corner, produced on the lower surface of the airfoil when the flap is deflected, generates a shock wave whose intensity is stronger than those of the two interacting shock waves. This produces a consistent increment of pressure and heat flux on the lower surface of the flap, where a thermal protection system is required.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.565-574
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• 2007

The flow control effect of blending Gurney flap with jet flap for flow around an NACA 0012 airfoil was numerically investigated through parameter variation of each flow control mechanism on unstructured meshes. The aerodynamic force and moment variations due to flow control were examined, and the results were compared between the blending control and each individual flow control. The results showed that the blending control required less energy input to achieve the same level of lift increment than that of the jet flap, and at the same time alleviated drag increment caused by introducing the Gurney flap.

• Advances in aircraft and spacecraft science
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• v.1 no.1
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• pp.69-91
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• 2014

Numerical investigations are presented, which show that a back-flow flap can improve the dynamic stall characteristics of oscillating airfoils. The flap was able to weaken the stall vortex and therefore to reduce the peak in the pitching moment. This paper gives a brief insight into the method of function of a back-flow flap. Initial wind tunnel experiments were performed to define the structural requirements for a detailed experimental wind tunnel characterization. A structural integration concept and two different actuation mechanisms of a back-flow flap for a helicopter rotor blade are presented. First a piezoelectric actuation system was investigated, but the analytical model to estimate the performance showed that the displacement generated is too low to enable reliable operation. The seond actuation mechanism is based on magnetic forces to generate an impulse that initiates the opening of the flap. A concept based on two permanent magnets is further detailed and characterized, and this mechanism is shown to generate sufficient impulse for reliable operation in the wind tunnel.

• Archives of Craniofacial Surgery
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• v.9 no.2
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• pp.110-113
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• 2008

Purpose: The jejunal free flap is the most standard and reliable procedure of reconstruction of the circumferential pharyngoesophageal defect because it provides pliable, elastic, secreting mucosa and posses reliable vascular anatomy. In this report, the authors introduce the modification of jejunal free flap for decreasing the complications in fatty complicated patients. Method: After harvesting the jejunum with mesentery and mesenteric vessels, both ends of jejunum were excised remaining the mesenteric portion. The jejunal portion of this composite flap was placed to reconstruct esophagopharyngeal defect area and the mesenteric portion was used to obliterate the dead space at paratracheal region and to cover the vital structure and the vascular anastomotic region. Result: A 72 year-old man with recurrent hypopharyngeal cancer who had about 15 cm sized circumferential pharyngoesophageal defect after total pharyngectomy was reconstructed with jejunomesenteric composite free flap without any complications. Conclusion: The mesenteric flaps at both side of jejunomesenteric composite free flap provide the advantages that could obliterate dead space, that could provide cover for the vital cervical vascular structure in case of vascularity was compromised due to previous radiation therapy, and that could preserve as much vascularity at both ends of jejunal flap as possible.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.568-572
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• 2000

A numerical investigation was performed to determine the effect of airfoil thickness on the optimum Gurney flap height using NACA 00XX series airfoils. Seven airfoils which have 3% chord thickness difference were used. These were NACA 0006, 0009, 0012, 0015, 0018, 0021, and 0024. A Navier-Stokes code, FLUENT, was used to calculate the flow field about airfoil. The fully turbulent results were obtained using the standard $k-{\varepsilon}$ two-equation turbulence model. To provide a check case fur our computational method, numerical studies for NACA 4412 airfoil were made and compared with already existing experimental data for this airfoil by Wadcock. For every NACA 00XX airfoil, Gurney flap heights ranging from 0.5% to 2.0% chord were changed by 0.5% chord interval and their effects were studied. With the numerical solutions, the relationship between $(L/D)_{max}$ and airfoil thickness as a function of flap height and the relationship between $(L/D)_{max}$ and flap height as a function of airfoil thickness were investigated. The same relationship for $(C_l)_{max}$ also were shown. From these results, the optimum flap size for each airfoil thickness can be determined and vice versa.

• Archives of Reconstructive Microsurgery
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• v.14 no.1
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• pp.18-23
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• 2005

Purpose: To report the results and the efficacy of the sensory bearing scapular free flap which is known as non-sensible flap. Materials and Methods: Authors underwent 24 cases of sensory bearing scapular free flap to the hands and feet from March 1995 to November 2002. average follow-up period was six year three months. The used flaps were a ordinary scapular flap in fifteen cases, and a parascapular flap in nine. Sensibility of the flaps were checked every one month. Actual sensory evaluation was mostly depends on objective feeling of the patients. Two point discrimination test was performed in all cases. Results: 23 flaps had good skin circulation after microvascular anastomosis among 24. Objective deep touch sensation were observed about three months later after the operation in three cases, between three and six months in nine. In three case whose results were excellent than others, two point discrimination was 2.7 cm at last follow-up. Most of the sensory recovery is confined in deep touch, temperature and light touch sensation was recovered limitedly in 3 cases during our follow-up period. Conclusion: Authors can propose that sensory bearing free scapular flap was considered as one of useful methods for the reconstruction to hand with soft tissue defect and mutilating hand.

• Archives of Reconstructive Microsurgery
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• v.14 no.1
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• pp.42-49
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• 2005

Between June 1989 and may 2004 Ipsilateral vascularized fibular transposition was performed on nine patients with segmental tibial defects combined with infection following trauma. Ipsilateral vascularized fibular graft was performed on two or three stage according to the degree of infection. Initially free vascular pedicled graft was done followed by ipsilateral vascularized fibular graft. Type of free flap used is scapular free flap 3 cases, latissimus dorsi free flap 5 cases and dorsalis pedis flap 1 cases. The patients were followed for an average of 3.4 years. the average time to union was 6.7 months, and in all patients the graft healed in spite of complication. Complication was free flap venous thrombosis in 1 cases, persistent infection in 1 cases, delayed bony union at the distal end of fibular graft in 2 cases. The results showed that more faster bony union was seen in which cases firmly internally fixated and more faster hypertrophy of graft in which cases was permitted to ambulate on early weight bearing and more faster healing in which cases debrided more meticulously. Reconstruction of tibia defect with free flap followed by Ipsilateral fibular transposition is a useful and safe method to avoid the potential risk of infection for patients with tibial large bone defect and soft tissue defect associated with infection.

• Archives of Reconstructive Microsurgery
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• v.9 no.1
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• pp.80-87
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• 2000

Acute high speed accidents that results in full thickness skin defect and exposure of tendon, nerve, vessel and periosteum over denuded bone demands soft tissue coverage. Exposed bone often ensues chronic infection and requires free flap transplantation which surely covers defects in one stage operation and enhances transport of oxygen-rich blood and converts a non-osteogenic or partially osteogenic site into a highly osteogenic site, but exposed bone which had performed free flap transplantation sometimes necroses and needs secondary bone procedure. Scar contracture limits joint motion should be excised and covered with normal soft tissue to restore normal range of motion. Authors have performed the large latissimus dorsi myocutaneous free flap in 8 cases of extensive soft tissue defect and exposed bone lesion in the leg and 1 case of the flap was failed. The secondary ilizarov bone procedure was performed in 3 of 8 cases. 2 cases of large burn scar contracture and 1 case of posttraumatic scar contracture in lower extremity were restored with the large latissimus dorsi myocutaneous free flap. Authors concluded that large latissimus dorsi myocutaneous free flap is the most acceptable microvascular procedure in large soft tissue defect combined with exposed periosteum and bone requiring secondary bone procedure and in large burn scar contracture limiting knee joint motion.

• Archives of Reconstructive Microsurgery
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• v.23 no.2
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• pp.101-104
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• 2014

Reconstruction of soft tissue defects of the knee has always been a challenging task for plastic surgeons. Various reconstructive choices are available depending on the location, size, and depth of the defect relative to the knee joint. Defects on the knee joint have several characteristic features. The use of a free flap is preferred for reconstructions involving obliteration of large-cavity defects, but recipient pedicle isolation can be difficult because of the extent of the injury zone. Furthermore, the true defect during knee joint flexion is larger than during knee joint extension, and a durable flap is necessary for joint movement. We report for the first time on the use of pedicled perforator flaps for reconstruction of bilateral knee defects in a 76-year-old woman. The operative procedure required skeletonizing the perforators of an antero-lateral thigh flap and antero-medial thigh flap and rotating the flap in the defect. The patient returned to normal daily activity and had a full range of motion two months after the accident. The shorter operating time with decreased donor site morbidity and its durability make this flap a valuable alternative for soft tissue reconstruction of the knee.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1476-1477
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• 2008

This paper reports on a flexible flap valve actuated by electromagnetic force under a constant pressure source. The flexible flap valve consists of the three main components: a flexible flap with a steel disk embedded in PDMS, an electromagnetic actuator and two glass plates with inlet and outlet. Sealing lip structures for improving the valve characteristics are added on the outlet of the bottom glass substrate. The flap valve is fabricated by the spin-coating process, the EDM process, SU-8 mold process and oxygen plasma treatment. The dimension of an assembled flap valve is $12mm{\times}20mm{\times}28mm$. The stroke volume of the flap valve is measured for various pressures and open times. When the input voltage of 30 V is applied for 0.33 s, the minimum stroke volume of the flap valve is 70 ${\mu}L$ at 50 kPa.