VW-Aero Engine Cylinder Head Cooling Efficiency Investigation

Abstract

Light sport aircraft builders widely construct experimental aircraft for their personal enjoyment for both building and flying purposes. A variety of engines are used as powerplants for their aircraft. The Volkswagen (VW) automotive engine is one of the most reliable engine conversions for amateur-built aircraft. The aim of this paper is to investigate the cylinder head temperature of the VW-Aero conversion engine during flight conditions by using CFD. The models of the front and rear cylinder barrels include a cylinder head which is constructed with the addition of a baffle plate and air inlet design shape based on internal air flow patterns. The simulations were performed at a velocity of between 50–100 kt (58–115 mph) at a flying altitude of 6,000 feet as per typical flight conditions. The results showed that the rear cylinder lacked cooling air because it was obstructed by a front cylinder. The rear cylinder encountered heat soak conditions which resulted in higher temperature when compared with what the front cylinder experienced. At a velocity of below 80 kt (92 mph), the incoming air velocity through the engine air duct was inadequate to maintain the engine cylinder’s head temperature so that it rises above a normal operating temperature range. At a velocity of above 80 kt (92 mph), the internal baffle plate was capable of feeding air through the controlled path between baffle plate and cylinder fin, which consequently resulted in a controllable engine cylinder barrel and head temperature to be within the normal operating temperature range. The aircraft flying at a velocity of less than 80 kt (92 mph) and equipped with a VW engine would be likely to experience an overheated engine problem due to insufficient cooling air.