Deflection of balancing disc in a multistage centrifugal pump, being the consequence of pressure forces, causes the change of shape of the axial clearance between the rotating balancing disc and the stationary counterdisc. It results in reduction of axial force acting on the rotating wall of the clearance, and the total balancing force. The final effect is a significant decrease (e.g. of 20%) of disc to counterdisc distance. The approximate formulae for radial pressure distribution in turbulent flow through hydraulically smooth conical axial clearance are derived in the paper and a numerical example is given. The method of integral relations was applied.

The authors describe the program undertaken at the Warsaw University of Technology (WUT), aimed at developing mobile aerodynamic laboratories to be used for investigation into aerodynamic properties of airfoils or lightweight propulsion systems - in natural scale and in natural atmosphere. The enterprise was named the EB-program, and has both: research and educational aspects; in all phases of the program (i.e. design, manufacturing and testing) the WUT students are involved. As the result of work, three mobile aerodynamic laboratories were build: EB-1 - which was tested on the car roof, EB-2 - unique flying laboratory based on the PW-6 glider, and EB-3 - a new generation of flying wind tunnel to be used on the AOS-71 glider, which currently is under preparation to the flight tests. The authors present in detail the measurement systems and procedures supported by the Lab View software.

An alternative FEM algorithm of fi nding piston ring pressure distribution to a contact simulation is introduced. The method is basing on an analytical determining of required nodal displacement boundary conditions. Its several confi gurations are tested using APDL and compared to a no-separation contact simulation of a simple 2D fi nite element model of a two-stroke piston ring made of Titanium alloy. Each of the methods tested in the paper brings displacement result and Huber-Misses equivalent stresses close to each other. However, only one of those brings resulting contact pressure close to a no-separation contact simulation. Nonetheless, the obtained confi guration occurred to be less computationally effi cient than no- separation contact simulation performed in an ANSYS software.

Ballast layer has weighty share in the lifecycle costs of railway track. The strict standards and maintenance rules of ballast grading significantly contribute to the ballast costs. One ways to the costs reduction is differential demands to ballast grading for the secondary and low loaded railway lines. Additional one is the different ballast grading over the ballast height. This study presents a full scale laboratory investigation of technical efficiency of such railway ballast under the long-term cyclic loading in comparison with the standard ballast layer. The double layer is presented with standard grading ballast upper layer and bottom sub ballast layer consists of ballast mixture. Pressure distribution under the ballast layer and permanent settlements of the layers are measured during the loading cycles. The reference measurements with standard grading ballast material are carried out. The study shows that initial settlement accumulation of the double layer railway ballast are lower to that of the standard ballast layer. However, the settlements accumulation intensity of the ballast is higher. The analysis of the pressure distribution measurements under the ballast layer and the settlements inside the ballast layer explain the causes of the different settlement accumulation.