A Convenient Technique for Determining Comparative Volumetric Efficiency

Design and development of a microwave-enhanced diesel soot oxidation system

“…where, V st = surge tank volume V 1cyl = volume of one engine cylinder Another method of determining an appropriate surge tank volume for a given engine application was published by Roussopoulos (1990). In this publication, the Helmholtz resonator equation was used to size intake air surge tanks.…”

“…He found that the operating frequency of the engine had to be nearly three times greater than the resonant frequency of the surge tank in order to minimize the airflow pulsations. If it is assumed that the Helmholtz resonator equation is valid for pulsating exhaust flow through a surge tank with sinusoidal velocity pulsations (with amplitudes on the order of the mean exhaust velocity) at the surge tank inlet and a flow resistance length, L, at the surge tank outlet; the following equation, as given by Roussopoulos (1990) for intake surge tanks, may be used to determine the minimum required surge tank volume:…”

“…where, f = exhaust pulsation frequency (Hz) RPM = engine angular speed (rpm) # cyl = number of engine cylinders Using Equation 3.3.24 for 6-cylinder engine operation at 1500 rpm, the exhaust pulsation frequency was found to be 75 Hz. According to Roussopoulos (1990), the surge tank resonance frequency was required to be 1/3 of this value (25 Hz). The distance between the surge tank outlet and the first orifice meter upstream pressure tap was approximately 12" (0.305m), and the outlet pipe diameter was 2.345" (cross-sectional area = .00279m 2 ).…”

“…Substituting these values in Equation 3.3.22, the minimum required surge tank volume for the engine operating conditions used for this research was calculated as, Using Equation 3.3.22, the required surge tank volume was calculated to be 0.278 m 3 or 73 gal. It is apparent that, according to the model proposed by Roussopoulos, an extremely large surge tank would be required if test conditions at idle were necessary (Roussopoulos, 1990). It must be noted that many simplifying assumptions were used by Roussopoulos in his derivation of the Helmholtz resonator equation for intake surge tanks, so care must be used if this method alone is to be used for surge tank sizing.…”

“…It must be noted that many simplifying assumptions were used by Roussopoulos in his derivation of the Helmholtz resonator equation for intake surge tanks, so care must be used if this method alone is to be used for surge tank sizing. Roussopoulos (1990) also stated that if the surge tank or transfer pipe dimensions approach the half wavelength of the acoustic waves at the operating frequency, then the surge tank system would actually amplify the pulsations instead of attenuating them. The half wavelength was calculated using the following equation (Roussopoulos, 1990)…”