using huggins equation with two test temperatures viscosity

In simple terms, empirical relationships do not satisfy the need of a readymade metric for viscosity-temperature characteristics for a common user of lubricants. The reason behind such ambiguity lies in the need of huge experimental data in order to reliably fit each of these equations. This model proves to be more useful in engineering calculations and predictive numerical models.ĭespite of the development in temperature-viscosity characteristics in empirical terms, some of which are useful for engineering calculations nevertheless, they often appear to be less useful as a quick guidance for practitioners. to follow only an exponential curve), it may work well only over a limited temperature range for a limited range of products.Īnother model was proposed by Vogel:, where x, y, and z are empirical constants. This equation appears to be simple and can be easily implemented in mathematical models but owing to its highly conservative functionality (i.e. Where is dynamic viscosity, and are empirical constants. Reynolds have pioneered in this direction and prescribed an exponential fit to describe the declining trend of viscosity with respect to temperature. Over the years, attempts have been made to develop empirical relationships to describe the lubricants temperature-viscosity behaviors. An attention to the temperature-viscosity characteristics of lubricants is therefore of practical importance for ensuring the lubricants desirable performance in any particular system. Thereby, neither a thick nor a thin lubricant can be the suitable choice that an engineer can make during the selection of lubricant. In such cases, lubricants get thicker and add up resistance to the movement of elements. On the other hand, viscosity of lubricant can also be critical for the performance of applications at sub-zero atmospheres. Another major source of heat is the high temperature operating environment (e.g. gears, bearings, engines), temperature rise due to friction induced heating is inevitable. Loss in lubricants viscosity may lead to severe performance issues of mechanical systems in industry and transportation applications. Oil viscosity often declines rapidly with respect to rise in temperature. Sustainability of lubricating film between contacting bodies in mechanical systems is often critical owing to the highly sensitive nature of lubricants temperature-viscosity relationship. Temperature-viscosity characteristics of lubricating oils and/or greases is one of the important determinant for lubricants performances in mechanical systems.

However, it is also known that temperature impacts the viscosity.

It is well-known from Hydrodynamic Lubrication Theory that viscosity plays a central role in the lubrication regime encountered in the machine element – the higher is the viscosity, the thicker is the oil film that separates the surfaces from touching each other. Viscosity is a measure of a lubricating oil’s resistant to flow.

Using huggins equation with two test temperatures viscosity