Probably the most difficult flow measurements for that automotive engineer would be to appraise the engine oil flow rate under operating conditions. Using the engine installed on an evaluation bench and coupled to some dynamometer, the task is slightly simpler because of the elevated space availability, but none of them the less, and careful selection and installing of the flow measurement product is needed. Flow measurements needed within the engine bay of the vehicle become further restricted because of instrument power requirement, installation space needed and also the harsh under bonnet conditions.
Do you know the flowmeter options? Well, industry standards appear to exist to some degree, but it doesn't mean they're correct. Let's explore some options.
The positive displacement meter, this may be by means of a gear meter, piston meter or helical screw to mention a couple of. These meters are usually around the greater cost side and may cause issues when installed because of their relatively ruthless drop. Although quite proficient at operating across wide viscosities they are doing are afflicted by meter slippage at low viscosities. Meters vary in dimensions, but could frequently be installed without resorting to any flow conditioning. Utilized by some engine test houses although not a perfect solution mobile fuel dispenser.
Turbine flow meter, generally probably the most broadly used flowmeters for engine oil flow measurement, mainly because of its low costs and small size. They may be purchased relatively easily from a number of manufacturers and also have a manageable pressure drop which isn't too harmful to grease system performance.
They're responsive to oil and fluid flow profile effects, so it's very vital that you calibrate the flow meter over the different oil viscosity range with its installed upstream and downstream flow conditioning tubes. To make sure accurate results while in use, it is important to match the installed conditions as near as you possibly can. Quite frequently specialist flow calibration laboratories will calibrate the flow meter on a single engine oil, in the same operating temperature along with the same inlet and outlet connections as reported by the installed engine. Sometimes this can be area of the engine set up, just like an oil cooler or oil filter set up, usually the easiest area of the engine in which the oil flow could be interrupted. Many flow meter manufacturers only give a calibration certificate on water, be responsible for very large errors if utilized on engine oils.
Coriolis meters. Excellent high precision meters that will simply be suitable for fixed installations. These meters remain highly costly and therefore are large in dimensions, when compared to turbine and positive displacement meters. These meters have progressed well during the last ten years, but can nonetheless be vulnerable to poor installation, vibration and nil drift measurement errors. Well suited for test bench use where they're permanently installed, with straight tube models now being a norm, they provide low pressure drop and ideal viscosity rangeability.
Pressure Drop Portrayal. An more and more common way of acquiring accurate measurements without having affected the oil system performance because of insertion of flowmeters. Individual areas of the engine oil flow system are instrumented for pressure tapping locations and every engine part is flow characterised on the calibration bench for oil flow against pressure drop in the needed temperatures. Once each system continues to be characterised the engine is reassembled and tested, and also the recorded pressure measurements will be accustomed to derive the flow rate. This process is usually utilized on critical engine lube surveys, in which the insertion of the flow meter might have a harmful impact on the oil flow system.
Ultrasound Clamp on meter. Although a non intrusive device, because of its straight pipe installation needs, it will mean the machine becomes intrusive in to the oil measurement system. Still highly costly to buy, and presently not sufficiently tested during these applications to become appropriate contender, although progressing quicker than other techniques.