Determining Hydraulic Ram Pump Feasibility

Abstract

Hydraulic ram pumps have been used for over 200 years to pump water using only the potential energy of elevated water. Today, the low price and simplicity of the materials and methods required to construct ram pumps make them an excellent option for small and mid-sized water systems in developing countries where elevated water is available. However, ram pumps are risky to implement because they will fail to deliver water if they are not designed correctly. Evaluating pump designs requires complex computer modeling typically unavailable in developing countries. Existing design documents for users without a specialization in fluid mechanics use vague rules of thumb to simplify the design process. Unfortunately, these rules cannot reliably predict whether or not a ram pump will deliver water in many cases.  Recent research has focused on developing pump efficiency equations from non-dimensional analyses of experimental data, developing guidelines to optimize designs, and modeling ram pump function with numerical methods. Currently, the literature has not provided the typical designer with accurate and accessible methods for predicting the maximum delivery head or the delivery flowrate of a specific design. This study models the acceleration of fluid in the drive pipe and the intensity of the pressure spike to determine the feasibility of a wide variety of ram pump designs with a higher degree of certainty than previous rules of thumb. The model can be used in a Matlab program that determines if a design will function based on design parameters input by the user. The Matlab method was used along with conservative assumptions to predict the minimum design characteristics required for several common scenarios for easy reference. This work will allow a wider proliferation of hydraulic ram pumps through more accurate design tools, and reduce the cost of water systems for small developing communities.