• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 춘계학술대회 논문집
• /
• pp.685-689
• /
• 2004

Numerical simulation is conducted to clarify the heat transfer and fluid flow characteristics of HVAC(Heating, Ventilating and Air-Conditioning) for double' deck train. The HVAC system is installed under the roof of carbody. In the lay-out of HVAC system, air duct must be installed to supply air to 1st and 2nd floor respectively. The standard k-$\epsilon$ and LES models for turbulence and SIMPLE algorithm for pressure equation hased on finite volume method are used to solve the physic a] HVAC model. To assure convergence, QUICK scheme for momentum equation and the 2nd order upwind scheme for turbulent equations arc used. From the results of simulation, the temperature and velocity magnitude are also distributed uniformly in the interior of double-deck passenger car.

• Journal of Mechanical Science and Technology
• /
• 제15권8호
• /
• pp.1188-1195
• /
• 2001

A numerical analysis has been carried out to investigate the influences of thermosolutal convection on the heat and mass transfer and solute segregation in crystals grown by the vertical Bridgman technique. The governing equations are solved by a finite-volume method using the power law scheme and the SIMPLE algorithm in which body-fitted coordinate system has been used. A primary convective cell driven by thermal gradients forms in the bulk of the domain, while a secondary convective cell driven by solutal gradients forms near interface. As the solutal Rayleigh number increases, secondary cell becomes to be stronger and has a great influence on the radial concentration along the interface.

• 대한기계학회논문집B
• /
• 제25권5호
• /
• pp.619-626
• /
• 2001

The present experimental and numerical study investigate flow and natural convection heat transfer characteristics of a composed rectangular-parallelogrammic enclosure with a guide vane. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a modified SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term. In this results of experimental study, the natural convection heat transfer characteristics was well coincided with conclusions of other earlier experimental researches and numerical analysis.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2000년도 춘계 학술발표회 논문집
• /
• pp.229-235
• /
• 2000

A study on the improvement of anti-abrasion nature of curved ducts for high-velocity gas-solid flow which are typically equipped in a coal-burned steam power plant has been investigated numerically and experimentally. To reduced the abrasion of pipe by particle, we have tried to form the vortex flow field in the region where flow changes its direction , modelled with two different shapes. 22.5$^{\circ}$and 90$^{\circ}$ elbows. the governing equations for three -dimensional , turbulent flow fields are discretized by FVM and solved bySIMPLE algorithm . From the numerical analysis, the new designed elbows for reducing abrasion have been developed. Numerical results are compared with the experimental abrasion data which are obtained from one of the operating coal burned steam power plants in Korea. Comparison of these results show that the developed elbows have much more durability than the original one.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 추계학술발표회논문집(1)
• /
• pp.617-624
• /
• 1997

This Paper Presents an effective and simple procedure for the simulation of the motion of the solid-liquid interfacial boundary and the transient temperature field during phase change process. To accomplish this purpose, an iterative implicit solution algorithm has been developed by employing the dual reciprocity boundary element method. The dual reciprocity boundary element approach provided in this paper is much simpler than the usual boundary element method applying a reciprocity principle and an available technique for dealing with domain integral of boundary element formulation simultaneously. The effectiveness of the present analysis method have been illustrated through comparisons of the calculation results of an example with its semi-analytical or other numerical solutions where available.

• 대한기계학회논문집
• /
• 제17권10호
• /
• pp.2590-2600
• /
• 1993

The present paper describes numerical predictions for the film cooling effectiveness from a row of hole at various injection ratios and injection alngles.Numerical calculations were performed to investigate film cooling effectiveness and the characteristics of flow and temperature distributions in the region near the downstream of injection hole including the region of adverse pressure gradient. The elliptic 3-dimensional governing equations with variable thermal properties were solved by SIMPLE algorithm. The results showed that the presence of adverse pressure gradient in the region near the downstream of injection hole induces large temperature gradient. At injection angle of $35^{\circ}$ the average film cooling effectiveness was increased as increased of injection ratio up to 1.0. At injection angle of $90^{\circ}$ however, the average film cooling effectiveness was decreased from injection ratio larger than 0.4.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.1613-1618
• /
• 2004

Diffuser is an important fluid-mechanical equipment to convert kinetic energy into pressure energy. Many of the experimental and theoretical researches have been done in a diffuser but the understanding of energy transfer and detailed mechanism of energy dissipation is unclear. In this study, computations were performed using a numerical method with SIMPLE algorithm for conical diffuser with various diffuser angles and diffuser lengths. Also, we investigated the pressure recovery coefficient in conical diffuser by inserting strut. In this paper, we showed that the strut can cause a rising pressure recovery.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
• /
• pp.257-263
• /
• 1999

The flow characteristics of double suction pump are investigated by numerically Calculations are performed by using SIMPLE algorithm at the design and off-design points. Symmetric nature of flow fields in blade channels is discovered at design point, but asymmetirc effects are discovered at the off-design point. Numerical results show that the formation of secondary flow in volute of double suction pump shows different trends when compared with the case of single suction pump. Also results show that double vortices are formed in the volute cross section.

• 한국추진공학회지
• /
• 제4권4호
• /
• pp.59-69
• /
• 2000

2차인 압축성/비압축성 Navier-Stokes 방정식은 이용하여 DCA 압푹기 익렬의 수치 해석을 수행하고 실험치와 비교 검토하였다. SIMPLE 알고리즘을 적용한 비압축성 코드는 대류항의 이산화에 하이브리드 도식을 진동해를 방지하기 위해 집중격자 기법을 사용하였다. 압축성 코드는 예조건화 기법 을 적용하였으며 공간 이산화출 위해 풍상 차분법을, 시간 적분을 위해서는 LU-SGS 기법을 사용하였다. 또한 난류 점성 유동장을 해석하기 위해 Baldwin-Lomax, standard $\kappa$ -$\varepsilon$, $\kappa$ -$\varepsilon$ Lam. Bremhorst, standard $\kappa$-$\omega$, $\kappa$ -$\omega$ SST 모델 등의 난류 모델을 적용하여 각 모델들의 특성을 살펴보았다.

• 대한기계학회논문집A
• /
• 제20권5호
• /
• pp.1458-1467
• /
• 1996

A direct differentiationmethod is presented for the shape design sensitivity analysis of axisymmeetric elastic solids. Based on the exisymmetric boundary integralequaiton formulation, a new boundary ntegral equatio for sensitivity analysis is derived by taking meterial derivative to the same integral identity that was used in the adjoint variable melthod. Numerical implementation is performed to show the applicaiton of the theoretical formulation. For a simple example with analytic solution, the sensitivities by present method are compared with analytic sensitivities. As an application to the shape optimization, an optimal shape of a gas turbine disc toinimize the weight under stress constraints is found by incorporating the sensitivity analysis algorithm in an optimizatio program.