Steady Flow Test Rig Research Articles

Experimental and numerical analysis of the in-cylinder swirl flow dependence on the pressure

The steady flow test rig is a device for studying the influence of the intake and exhaust ports of the cylinder head on the flow motion inside the cylinder in internal combustion engines. In this paper, the swirl flow as a critical mixing mechanism inside the cylinders of internal combustion engines has been investigated by the vane type swirl meter measurement system in the steady state flow test rig with experimental and numerical simulation methods. In numerical simulations, the in-cylinder flow in the presence of the swirl meter is modeled using the multiple reference frame (MRF) method. Three dimensional numerical simulations are applied by using the finite volume method. The simulation results show good agreement with experimental results and showed to be a good alternative to compensate the limitations of the operating conditions of the test rig. In this work, a linear correlation between the rotational speed of the swirl meter and the torque is found. The study also showed that by increasing the pressure difference between the inlet and outlet of the cylinder, the speed of the in-cylinder swirl flow increased where a correlation between swirl flow velocity and pressure difference is proposed using an exponential function. The in-cylinder swirl flow velocity was determined for different test pressure and for different distance the vane-type swirl meter from cylinder head and it was seen that it is maximum when the vane-type swirl meter is located at 1.3 D from cylinder head for different test pressure.

Influences of intake ports and pent-roof structures on the flow characteristics of a poppet-valved two-stroke gasoline engine

In order to minimize the short-circuiting of the intake charge in a poppet-valved two-stroke engine, a “step structure” on the intake side of the pent-roof was employed to shroud the bulk flow at the upper periphery of the intake valves at low valve lifts. Several intake-port geometries and pent-roof angles were evaluated on their charging and reversed tumble generating abilities using a steady flow test rig built in computational fluid dynamics, among which top-entry ports and relatively small pent-roof angle were selected. The scavenging processes of the two-stroke engine at high load and 3000 r/min condition with different intake valve seat heights were simulated and evaluated. The local flow patterns and composition distribution were also studied. The results show that lowering the intake valve seat height achieves higher delivery ratio and charging efficiency, but marginally better scavenging efficiency and slightly lower trapping efficiency. The scavenging process experiences a slow displacement period due to low flow momentum for the high valve seat cases and flow interaction at the exhaust exits for the low valve seat cases. Reversed tumble is the dominant flow pattern during the scavenging process. The lower the valve seat, the higher the tumble ratio in the early stage and at the end of the scavenging period. For all valve seat configurations, the least scavenged regions are located near the engine head wall and between the intake and the exhaust valves, while the regions rich in fresh charge are located along the major path of the reversed tumble. Low intake valve seat height is effective in increasing the overall in-cylinder air proportion. Further reducing it can result in higher fresh charge proportion below the exhaust valves and near the head wall.

정상유동장치를 이용한 유량계수 측정에 관한 실험적 연구

Abstract: Miller cycle is considered as an effective means to meet the regulation on Tier Ⅱ and to reduceCO 2 emission. For this cycle, the amount of intake air supplied should be enough increased. Therefore, theintake system with minimized resistance for air flow is under consideration. In this study, the flow coefficients of intake valves were measured in order to obtain the basic data for the cycle simulation andintake port design. The flow coefficients were measured using the steady-flow test rig. As a test result forthe poppet valve used the marine engine with medium speed, the flow coefficients are increased to about0.62 with the valve lift. In addition it is confirmed that the flow coefficients have the characteristic valueirrelevant to the S/B ratio. Key words: Flow coefficient, Intake valve, S/B ratio, Steady-flow, Volume flow rate †교신저자(STX종합기술원 연소성능팀, E-mail: pivboy@onestx.com, Tel: 055-210-3385)1 STX종합기술원 연소성능팀2 창원대학교 전기공학과 대학원3 창원대학교 조선해양공학과 1. 서 론 최근 원유가 인상 및 전 지구적 환경오염 규제 강화는 저배기 및 고효율 기관 개발의 필요성을 증진시키고 있다. 특히 국제해사기구의 Tier Ⅱ 발효 및 지구온난화현상에 따른 CO

Experimental–theoretical methodology for determination of inertial pressure drop distribution and pore structure properties in wall-flow diesel particulate filters (DPFs)

Wall-flow particulate filters have been placed as a standard technology for Diesel engines because of the increasing restrictions to soot emissions. The inclusion of this system within the exhaust line requires the development of computational tools to properly simulate its flow dynamics and acoustics behaviour. These aspects become the key to understand the influence on engine performance and driveability as a function of the filter placement. Since the pressure drop and the filtration process are strongly depending on the pore structure properties – permeability, porosity and pore size – a reliable definition of these characteristics is essential for model development. In this work a methodology is proposed to determine such properties based on the combination of the pressure drop rement in a steady flow test rig and two theoretical approaches. The later are a lumped model and a one-dimensional (1D) unsteady compressible flow model. The purpose is to simplify the integration of particulate filters into the global engine modelling and development processes avoiding the need to resort to specific and expensive characterisation tests. The proposed methodology was validated against measurements of the response of an uncoated diesel particulate filter (DPF) under different flow conditions as cold steady flow, impulsive flow and hot pulsating flow.

Study on three-dimensional flow characteristics on the port of an engine

The current assessment methods of intake port by adopting discharge coefficient and swirl intensity measurement from a steady-flow test rig is a high-cost and time-consuming process. The three-dimensional flow model was built; flow characteristics and the law of variation in discharge were analysed in this paper. The measurement in the test rig verify the numerical results. The local optimisation and simulation analysis of the intake port were made in this study and reversed flow in the inside of the bending segment was eliminated, which increased the minimum circulation area and lowered the intake resistance. As a result, the flow coefficient of the intake port was greatly increased.

흡기시스템을 통해 실린더로 유도되는 공기의 3차원 Bulk Motion Index 개발 (I) - 3차원 유동해석결과를 중심으로 -

In order to figure out the physical meaning of 3-D angular flow index for in-cylinder bulk motion, CFD analysis for the swirl and tumble steady flow test rig were made using commercial package STAR-CD. Computer simulations and rig tests on some kinds of induced flow conditions were carried out. Finally, based on the comparison between the simulated results and measured results, the physical meaning of 3-D angular flow index /N<SUB>B</SUB>→/, βcomposed of swirl and tumble coefficients measured by steady flow test rig was described.

Study of the influence of nozzle seat type on injection rate and spray behaviour

A deep analysis of the injection rate characteristics and spray behaviour of the most used nozzle types in diesel engines [microSAC and valve covered orifice (VCO)] has been carried out. In order to compare the injection characteristics and the spray behaviour of both nozzle types, several experimental installations were used, such as the steady flow test rig, injection rate test rig, spray momentum test rig, and nitrogen test rig, to obtain a full hydrodynamic and spray characterization. The study of the flow in both nozzles was analysed under steady flow conditions in the steady flow test rig and in real unsteady flow conditions in the injection rate test rig and the spray momentum test rig. The macroscopic properties of the spray (tip penetration and spray cone angle) were characterized using a high-pressure test rig. From the point of view of the internal flow behaviour, the results showed interesting differences in the permeability of both nozzle geometries, with a higher discharge coefficient in the microSAC nozzle. However, from the point of view of air entrainment, the results showed a better quality of fuel-air mixing in the VCO nozzle. Besides the evidence from the experimental results, a theoretical analysis was carried out in order to identify the most important parameters that determine the spray behaviour and thus justify the different macroscopic behaviour of both nozzles.

An experimental investigation of two different methods for swirl induction in a multivalve engine

This paper describes an experimental investigation aimed at comparing the swirl effect induced by unbalancing the mass flow through the two intake ports of a multivalve engine head using two different methods: the first one reduced the curtain area of one of the intake valves [different lifts (DL) method]; the second one adopted a sluice-gate-shaped valve, installed upstream of the intake valves [swirl control valve (SCV) method] in order to cause a pressure drop. A steady-flow test rig (equipped with instrumentation for the discharge coefficient and swirl intensity measurement) was realized in order to compare and evaluate the results of both methods and determine their respective validity and limitations; the procedures used for both experimental methods are discussed in detail. The flow characteristics were analysed through changes of lift difference or SCV position; it was found that both DL and SCV methods are effective in swirl induction but the DL mechanism, acting on the valve curtain area, is more effective in flow unbalancing between intake ports, since the flowrate depends linearly on the curtain area. The SCV method, instead, controls the port flowrate, inducing a localized pressure drop, whose intensity depends on the flow velocity in a non-linear manner. For this reason the SCV method can achieve strong swirl intensity only with high obstruction levels, in a narrow regulation window close to full-obstruction conditions.

New evaluation indices for bulk motion of in-cylinder flow through intake port system in cylinder head

The purpose of this study is to find new evaluation indices for the bulk motion of in-cylinder flow instead of the current swirl or the tumble coefficient and ratio using a steady flow test rig on intake port systems. To do this, port flow rig tests were conducted on the double-overhead cam head. Finally, the angular flow coefficient (NA), the inclination angle (γ) the angular flow parameter (PA) and the flow angle (φ) were introduced as new evaluation indices for the bulk motion of in-cylinder flow.

New evaluation index for bulk motion of in-cylinder flow through intake port system in cylinder head (II)

The variable intake systems recently tend to be adopted in gasoline engines for fuel economy and emission regulation. In the cases, because both swirl and tumble flows are together induced to the cylinder, in-cylinder flow pattern becomes very complicated so that we cannot decide this flow as one major pattern like swirl or tumble. The purpose of this study is to find new evaluation indexes for in-cylinder flow characteristics instead of a current swirl or a tumble ratio at the end of intake stroke using a steady flow test rig. To do this, port flow rig tests were conducted on the DOHC head varying lift of intake valves. Finally, the angular flow parameter PA and the flow angle (φ) were introduced as new evaluation indexes for in-cylinder angular flow characteristics at the end of intake stroke.

A study on the effects of intake port eccentricity and a partition between the two intake ports on the in-cylinder swirl characteristics in a valve diesel engine

The effects of intake port eccentricity and a partition between the two intake ports on the incylinder swirl characteristics in a 4 valve diesel engine having the two intake ports, one is a helical intake port and the other is a tangential intake port, were investigated by using the impulse swirl meter(ISM) in a steady flow test rig. Mean flow coefficient ( , swirl ratio ( ) and the mass flowrate through the two intake ports with and without intake port partition were measured. The results showed that the characteristics of in-cylinder swirl ratio formed by a 4-valve cylinder head were largely affected by valve eccentricity ratio ( ) and the existence of an intake port partition between the two intake ports. Mean flow coefficient ( ) increases and swirl ratio ( ) decreases in case of being the partition between the two intake ports. And also the mass flowrate through the tangential intake port is 19.0% and 7.7% more than that of the helical intake port in case of the two intake ports with and without partition respectively.ively.