Software for Fluid Power Technology

From Editor

The purpose of the Software Review section of the Journal is to present information to the reader about engineering software, including simulation programs, to highlight their specific features and their "fitness to purpose" in the unique field of fluid power and motion control. It is, of course, impossible to establish evaluation criteria matching the needs of all readers, therefore readers should not look for absolute ratings but more or less "fuzzy" opinions of the reviewer. A software program is like a wrench, just a tool to solve problems. It is good to solve some problems and not so good for others and this depends on both the nature of the problem and the users' attitude - and generally when we review software we do not know either. A software tool can be highly specialised and great for a some applications but not so well suited for others, on the other hand another software tool can be more flexible and generally applicable but without outstanding features. It is impossible, and even misleading, to say which one is better. What we hope to accomplish is to give the reader information necessary to take his/her own decision.

IESHYD010V01 - Hydraulic Components Sizing Calculator
Medhat.K. Bahr Khalil* Shajan John**

*Professional Education Instructor, Fluid Power & Motion control, khalil@msoe.edu
** Director, Professional Education and Research Development, johns@msoe.edu
Milwaukee School of Engineering; Applied Technology Center
1025 North Broadway, Milwaukee, WI, 53202-3109, USA

Introduction

Hydraulic Components Sizing Calculator is software designed to estimate interactively the proper size of the most frequently used hydraulic components based on static characteristic equations.
Using such software saves the time of the hydraulic system designers and components distributors by helping them to do the routine calculation required to select adequate hydraulic component for a specific application. It can make it easy even for the non-technical people to respond quickly to an inquiry with a professional answer.
Fluid power instructors are the second important category of users that can benefit from such software. They can use it to demonstrate interactively the effect of different design parameter and operating conditions on the hydraulic component performance. It can be used also as a problem solver to prepare exam questions with model answers. The software is designed to be presented using projector of 600x800 standard resolution.
Two systems of units, report generator, formulas used, well defined inputs/outputs, saving and printing utilities are included features to help the user to file, organize and share the calculation results with coworkers and externally.

Contact Information

Internet Site: www.CompuDraulic.com

Vendor: CompuDraulic Enterprise

Contact Person: Dr. Medhat K. Bahr Khalil

Telephone Number: 414-243-8199

Fax Number: 414-304-8314

Email: medhat@compudraulic.com

Platform: WinNT, Win20 andWin XP

User Interface

The user interface of the software is shown in Fig. 1. The user interface consists basically of a parent window and a number of child windows.

The parent window contains in the upper part a toolbar while the lower part is dedicated for the calculation. As shown in Fig. 1, the first six icons of the tool bar are reserved for the hydraulic component library. It starts from the left by the pump followed successively by motor, cylinder, cylinder buckling, accumulator and conductor. Further work is in progress to add more components to the library. When any of the hydraulic component icons is pressed, caption of the main window will be changed accordingly and the corresponding child calculation window will appear and maximize within the main window.

Child calculation windows for various components can be opened at the same time so that interrelated calculations can be conducted. On each child window there are well defined set of inputs and outputs that specify the static characteristics of the selected hydraulic component. On each child window, a set of scroll bars are used to change the inputs. Limits of these scroll bars are specified to cover the most commonly known working conditions. However, if the user inputs non-feasible working conditions, a warning will be provided by the software.

The icon following the component library is for the user to switch between the English and SI system of units. Calculations are then changed accordingly and instantaneously. The following icon is to generate a PDF file of all the formulas used in the calculation. The icon before the last is to generate a timed and dated notepad calculation report ready for printing, saving and archiving in electronic form. The last icon is for the user to access the help and read me files.

Double-click the images to enlarge them
and click once to make them thumbnail size again.

Fig. 1: User Interface

Calculation Example

In this example, a fixed displacement pump is to be selected for a specific application using SI system of units. The maximum available power in this application equal 15.05 kW. The software is required to answer the question of “what is the maximum working pressure and what is break down of the pump efficiency” if:

•   Maximum available power = 15 hp
•   Pump running at 1500 rpm
•   Pump displacement = 40 cc/rev
•   Pump mechanical efficiency = 95%
•   Pump volumetric efficiency = 90% (at 1500 rpm and 500 bar)

As shown in Fig.2, The software input scroll bars were adjusted to meet the aforementioned working conditions and the answers were found instantaneously inside the output data frame.

By clicking on the report generation icon, a date and time stamped report will be generated automatically on a notepad file as shown in Fig.3.

Calculation Scheme

The following calculations have been developed based on SI system of units and programmed. The software is fed by the required conversion units to convert the calculation results to the English system of units whenever requested.

Double-click the images to enlarge them
and click once to make them thumbnail size again.

Fig. 2: Pump Calculation Example Fig. 3: Report Generated

Operating Conditions:

np	Pump speed	rpm
Pp	Pump pressure	bar

Design Parameter:

Dp	Pump displacement cc/rev
Emp	Pump hydro-mechanical efficiency at the operating conditions	%
Evpd	Pump volumetric efficiency at specified operating conditions	%
nevpd	Pump speed at which efv is defined	rpm
pevpd	Pump pressure at which efv is defined	bar

Output Data:

Evp	Pump volumetric efficiency at new operating conditions	%
Qpt	Pump theoretical flow rate	L/min
Qpa	Pump actual flow rate	L/min
QpL	Pump leakage flow rate	L/min
Etp	Pump total efficiency	%
Npout	Pump output power	kW
NpL	Pump power losses	kW
Npin	Pump drive motor power	kW
Tshp	Torque on the pump shaft	N.m

BACK