• International Journal of Automotive Technology
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• v.7 no.4
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• pp.441-448
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• 2006

In-cylinder flows such as tumble and swirl play an important role on the engine combustion efficiencies and emission formations. The tumble flow, which is dominant in current high performance gasoline engines, is able to effect fuel consumptions and emissions under a partial load condition in addition to the volumetric efficiency under a wide open throttle condition. Therefore, it is important to optimize the tumble ratio of a gasoline engine for better fuel economy, lower emissions, and maximum volumetric efficiency. First step for optimizing a tumble ratio is to measure a tumble ratio accurately. For a tumble ratio measurement, many different methods have been developed and used such as steady flow rig, PIV, PTV, and LDV. However, it is not well known about the relations among the measured tumble ratios using different methods. The purpose of this research is to correlate the tumble ratios measured using three different methods and find out merits and demerits of each measurement method. In this research the tumble flow was measured, compared, and correlated using three different measurement methods at the same engine: steady flow rig; 2-dimensional PIV; and 3-dimensional PTV water flow rig.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.13-21
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• 2007

This paper presents characteristics of steady flow by variation of a combustion chamber and an intake port. Gas flow field inside a combustion chamber is the important factor in improving combustion stability and reduction of emission level. The flow characteristics such as flow coefficient, tumble ratio and swirl ratio are measured by the steady flow rig test with an impulse meter in this study. In the measuring, the valve lifts are varied between 1mm to 10mm. The three combustion chambers and two intake ports were applied to the steady flow apparatus in order to investigate the effect of swirl and tumble on the in-cylinder flow. As a result, tumble ratio were found to be different by variation of the combustion chambers and the intake ports. The data from the present study can be applied to design of a similar engine as basic data.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.43-49
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• 2006

Optimizing in-cylinder flow such as tumble or swirl is one of the key factors to develop better internal combustion engines. Especially, the tumble, which is more dominant flow in current high performance gasoline engines, has significant effects on the fuel consumptions and exhaust emissions under part load conditions. The first step for the tumble optimization is to find an accurate but cost-effective way to measure the tumble ratio. From this point of view, tumble ratios from three different measuring methods were compared and correlated in this research. Steady flow rig, water rig, and PIV were utilized for that purpose. Engine dynamometer test was also performed to find out the effect of the tumble. The results show that the tumble ratios from those methods are well correlated and that the steady flow rig is the effective method to measure the tumble despite its limitations.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.74-82
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• 2006

This paper describes the steady flow characteristics due to PDA and tumble control valve in combustion chamber. We also investigated the flow inclination angle defined as the inverse tangent of non-dimensional rig tumble(NRT) devided by non-dimensional rig swirl(NRS) to find dominant flow direction. So we adapted two different types of PDA valve(port deactivation valve) to strengthen a swirl flow. The in-cylinder swirl flow different tendency between with/without PDA valve. It might be thought to be affected by swirl flow. We could find that tumble ratio and swirl ratio is different by PDA valve. The comparison are taked account of the swirl, the tumble ratio comparison in same mass flow rate. As a result, PDA valve is better than tumble control valve both in steady flow condition and swirl, tumble ratio. The data from present study are available for design of engine as the basic data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.2
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• pp.166-174
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• 1999

The flow characteristics of 2-valve and 4-valve cylinder heads with various blocked-valve were experimentally investigated in a steady flow rig. Effects of the blocked-valve configurations on flow coefficient, swirl and tumble intensity are studied. Compared to the conventional valve, the blocked valve in both cylinder heads have the much lower flow coefficient and the much higher intensity of swirl and tumble. Under the same size of blockage, the value of flow coefficient and swirl(or tumble) intensity were varied according to the position of blockage. Throughout these steady flow test the optimized positions of blockage in both cylinder heads were determined.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.82-88
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• 1999

The object of this study is to find new evaluation index for in-cylinder flow chracteristics istead of current swirl, tumble coefficient using steady flow test rig on intake port system. To this end, port flow system. To this end, port flow rig test was conducted on DOHC head varying intake valve lift respectively. Finally combination angular coefficient and inclination angle were introduced as new evaluation index for in-cylinder angularflow characteristics instead of swirl and tumble coefficient.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.76-82
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• 1999

The object of this study is to find new evalution index for in-cylinder flow characteristics insteady of current swirl, tumble coefficient using steady flow test rig on intake port system. To this end, port flow rig test was conducted on DOHC head varying intake valve lift respectively. Finally combination angular coefficient and inclination angle were introduced as new evaluation index for in-cylinder angular flow characteristics.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.66-75
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• 1999

Many researchers have developed the measurement technique of in-cylinder flow. Recently, there are lots of studies on steady flow with different SCV geometries. In this study the flow characteristics of four-valve cylinder head were examined in a steady test rig for different SCV open ratios. Each swirl ratio of several SCV angle was quantified by swirl impulse meter and 2D-LDV measurement. The results showed that the swirl ratio was controlled between 2.3 and 3.8 based on SCV angles. The velocity distributions of in-cylinder flow field were measured by 2-D LDV test and visualized swirl and tumble flow pattern at different positions. In this engine , we found out that the swirl was dominant flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1057-1065
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• 2006

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 $|\longrightarrow_{N_B}|$, $\beta$ composed of swirl and tumble coefficients measured by steady flow test rig was described.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.5
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• pp.197-205
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• 1996

The flow characteristics of five different 4-valve cylinder heads were investigated in a steady flow rig using laser-Doppler velocimetry. The tumble flow of each head with pentroof combustion chamber was quantified by nondimensional tumble number using a tumble adaptor. The formation of tumbling vortex was examined in an optical single-cylinder engine which has windows for in-cylinder LDV measurements. Tumble vortex ratio was estimated from the tumble flow measurement. The four-valve cylinder heads with pent-roof combustion chamber showed the tumble vortex from the intake process, which was investigated in the steady flow test. The tumble adaptor which converts the tumble into swirl flow was found to be feasible in predicting the tumble flow in the real engine. The tumble strength in the steady flow test coincides with that in the real engine experiment within 15%. It was found that the steady flow test on the four-valve cylinder heads provides the tip for a better design of cylinder head.