Prediction Of Performance And Development Of Design Software For Car Pumps

The internal flow in a pump is very complicated and is far from being recognized because of the rotational impeller as well as the bent flow passage. The car pump studied in the paper is characterized with small volume but large flow, for it is always expected to be installed in the limited space and meet the performance requests. Some even have special inlet structure such as ring pipe, etc. Therefore, it's even more difficult to explore the inner flow mechanism and predict the performance of the car pump. The pump design still depends on semi-theory and semi-experience. Generally speaking, domestic pump development goes through the following steps: design-trial manufacture-experiment-improvement. Such a tedious process is really a waste of time, efforts and financial resources.The volute and inlet structures of existing car pump used in the modern car are always same. If the performance curve can be got precisely with the geometric parameters of the designed impeller in advance, it can not only significantly reduce the cost of modal making, trial manufacture and experiment, but also can decrease the design and manufacturing period.In order to find the way of reducing loss in the car centrifugal pump and predicting the performance curve, many domestic scholars have put forwards different flow patterns and loss calculation methods [1-3]. However, they work at design but not off-design condition. To discover the flow characteristics of car pumps at design and off-design condition, this article deal with three-dimensional flow at first and investigate performance predication based on the pump three-dimensional simulation results with which hydraulic loss in each component of pump is also attained. This provides abundant reference data for analyzing the flow patterns in the latter study. Then hydraulic loss method is mainly adopted to establish relations between hydraulic loss and flow parameters thus the loss models for car pumps are put forward. At the same time, the article treats with a car pump which doesn't satisfy the design condition. By analyzing numerical simulation, some structural improvement is made and the pump finally meets the required need.At last, the existing centrifugal pump loss modal is applied to the pump design software. So far, there's still no practical software to design car pumps in China. With the detailed study above, it's possible to get such software which employs the loss calculation expressions to get a suitable pump modal.The main research contents of this paper are below:(1)The present situations and trend on characteristics prediction of centrifugal pumps are summarized and then, the paper Conduct 3D numeric simulation of internal turbulent flow for existing car pumps produced by some corporation and attains performance curves as well as the loss of each component, which provides abundant data to study the loss models..(2)On the basis of hydraulic loss method and detailed analysis of the hydraulic modal of the car pumps, some mathematic expressions with high precision are proposed which reflect relations between inner Flow characteristic parameters(specific speed, flow rate, etc)and external characteristic parameters(efficiency, hydraulic head, etc)at both design and off-design condition.(3)When evaluating the hydraulic loss in the pumps, the article also discusses the geometry pragmatic influence on the pump performance and applies it to structure improvement of one car pump which doesn't satisfy the design condition. By establishing three-dimensional numeric simulation modal and analyzing the associated local flow fields and total pressure variation in the unwanted pump, the paper finally finds out the reasons why it deviate from the requirement and take the structure improvement measures. At last, the modified pump performance is proved to be largely advanced and the working range in the high efficiency is expanded. (4)Since the performance curves and the existing geometric modals of the car pumps have been acquired, the pump design software on the Windows platform with VB language is eventually developed. By employing the similarity principle and the above performance evaluation expressions, it's easy to get some proper pump model which can meet the users'flow, head and rotational speed requests.